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1 jan 2309 <?xml version="1.0" encoding="ISO-8859-1"?>
2     <!DOCTYPE book
3     PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
4     "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
5     [<!ENTITY imgscale "60">]>
6     <!-- $Revision$ -->
7     <book>
8     <bookinfo>
9     <title>Benutzerhandbuch für Thuban 1.0</title>
10     <authorgroup>
11     <author>
12     <firstname>Jonathan</firstname><surname>Coles</surname>
13     </author>
14     <author>
15     <firstname>Jan-Oliver</firstname><surname>Wagner</surname>
16     </author>
17     <author>
18     <firstname>Frank</firstname><surname>Koormann</surname>
19     </author>
20     </authorgroup>
21     <copyright>
22     <year>2004</year>
23     <holder>Intevation GmbH</holder>
24     </copyright>
25     <revhistory>
26     <!-- comment this first revision out when releasing a real version -->
27     <revision>
28     <revnumber>CVS version $Id$</revnumber>
29     <date></date>
30     <revremark>Under development.</revremark>
31     </revision>
32     <!--
33     <revision>
34     <revnumber>1.0.0</revnumber>
35     <date>nn-Mmm-2004</date>
36     <revremark>
37     Corresponds to Thuban 1.0.0.
38     </revremark>
39     </revision>
40     -->
41     </revhistory>
42    
43     </bookinfo>
44    
45     <chapter><title>Einführung</title>
46     <para>
47     Thuban ist ein interaktiver Geodaten-Betrachter.
48     Die Entwicklung wurde seinerzeit gestartet, da es zu dieser Zeit
49     keinen einfachen interkativen Betrachter für Geo-Daten als Freie
50     Software gab.
51     Thuban ist im wesentlichen in der Programmiersprache Python implementiert und
52     nutzt die wxWidgets (ehemals: wxWindows) Bibliothek die es erlaubt
53     Thuban auf verschiedenen Plattformen laufen zu lassen, darunter GNU/Linux
54     und Windows.
55     </para>
56     <para>
57     Geodatenbetrachter sind wichtige Werkzeuge die es gestatten, einen visuelle
58     Eindruck des räumlichen (gegenseiten) Bezuges von Informationen zu bekommen
59     die ansonsten anhand der reinen Daten nicht leicht ersichtlich sind.
60     Thuban erlaubt dem Benutzer, Sitzungen zu erzeugen, die geografische
61     Daten darstellen. Diese können dann erforscht werden indem er durch sie
62     sie navigieren und die Art der Darstellung ändern kann.
63     Die Ergebnisse können gespeichert oder gedruckt werden.
64     </para>
65     <para>
66     Thuban strukturiert eine Sitzung hierarchisch.
67     Eine Sitzung besteht aus Ebenen. Jede Ebene rerpäsentiert
68     einen bestimmten Datensatz.
69     Beispielsweise eine Ebene für Strassen und eine weitere für Gebäude.
70     Die Ebenen können sowohl Vektor-Daten beschreiben als auch Raster-Daten.
71     </para>
72    
73     <section><title>Installation</title>
74     <para>
75     Thuban is actively supported under Debian Testing (sarge), RedHat 7.2,
76     and Windows 2000. Thuban depends on the following packages. These
77     packages can also be found on the
78     <ulink url="http://thuban.intevation.org/download.html">
79     Thuban Download site
80     </ulink>.
81     </para>
82     <para>
83     Required:
84     <itemizedlist>
85     <listitem><para>Python 2.2.1
86     (<literal>http://www.python.org</literal>)
87     </para></listitem>
88     <listitem><para>wxWindows 2.4
89     (<literal>http://www.wxwindows.org</literal>)
90     </para></listitem>
91     <listitem><para>wxPython 2.4
92     (<literal>http://www.wxpython.org</literal>)
93     </para></listitem>
94     <listitem><para>proj 4.4.5 Projection Library
95     (<literal>http://www.remotesensing.org/proj/</literal>)
96     </para></listitem>
97     <listitem><para>SQLite 2.8.3
98     <literal>http://www.hwaci.com/sw/sqlite/</literal>)
99     </para></listitem>
100     <listitem><para>PySQLite 0.4.3
101     (<literal>http://pysqlite.sourceforge.net</literal>)
102     </para></listitem>
103     </itemizedlist>
104     </para>
105     <para>
106     Optional:
107     <itemizedlist>
108     <listitem><para>GDAL 1.1.8
109     (<literal>http://www.remotesensing.org/gdal/</literal>)
110     </para></listitem>
111     <listitem><para>psycopg 1.0.8
112     (<literal>http://initd.org/software/psycopg</literal>)
113     </para></listitem>
114     </itemizedlist>
115     </para>
116     <para>
117     Along with the source codes, the download page also offers full
118     installation packages for Debian, Windows and RPM-based systems
119     (Mandrake, RedHat, SuSE, etc).
120     </para>
121     <section><title>RPM-based GNU/Linux Systems</title>
122     <section><title>Installing Binary Packages</title>
123     <para>
124     The most wide-spread RPM-based GNU/Linux
125     Systems are RedHat, Mandrake and SuSE.
126     The documentation of these distributions
127     should contain information about how to
128     install third-party RPM packages.
129     Nonetheless, a short summary is provided here.
130     </para>
131     <para>
132     RPM packages can be installed applying several
133     tools. The most basic one is the command line
134     program "rpm". The hardware architecture is
135     identified in the name of RPM packages, eg.
136     'i386' for most Intel/AMD architectures.
137     If you have a different hardware architecture,
138     where no binary RPM packages are provided,
139     you must rebuild binary packages from the
140     RPM source packages first (see below).
141     Typical rpm commands look like:
142    
143     <programlisting>
144     rpm --install Thuban-0.9.0-1.i386.rpm
145     </programlisting>
146    
147     Depending on what you already have installed
148     on your system, you are informed that some
149     packages are required, but not installed.
150     You need to install them first. Either they
151     are provided by your GNU/Linux distributor
152     or available somewhere on the Internet.
153     The more essential and special ones are
154     provided together with the Thuban package.
155     </para>
156    
157     <para>
158     For rpm exist some graphical user interfaces, notably
159     kpackage, GnoRPM and xrpm.
160     </para>
161    
162     <para>
163     Make yourself familiar with one of the tools and apply it
164     to install the packages.
165     Note, that you need to be administrator (root) for the system
166     to do that.
167     </para>
168     </section>
169     <section><title>Build Binaries from Source Packages</title>
170     <para>
171     This section describes howto build RPM install-packages
172     from RPM source-packages.
173     This adapts and optimizes an install-package specifically
174     to your system.
175     This is especially helpful to resolve version conflicts of
176     dependent packages. Furthermore, install-packages for other
177     platforms (e.g. PowerPC) can be created.
178     </para>
179    
180     <para>
181     Note: rpm must be at least version 4. Execute
182     <literal>rpm --version</literal> to find out about the version.
183     </para>
184    
185     <para>
186     You need to do the following preparations to be able to
187     build the packages as a regular user. You should now
188     perform the package buling as root since this
189     might cause damage to your system.
190     <itemizedlist>
191     <listitem>
192     <para>
193     Create RPM directory structure:
194     Choose a directory (e.g. $HOME/myrpm) and create the
195     subdirectories BUILD, RPM, SOURCES, SPECS and SRPMS.
196     A possible command sequence for this is:
197     <programlisting>
198     mkdir $HOME/freegisrpm
199     cd $HOME/freegisrpm
200     mkdir BUILD RPMS SOURCES SPECS SRPMS
201     </programlisting>
202     </para>
203     </listitem>
204     <listitem>
205     <para>
206     Set environment variable RPM_DIR:
207     <programlisting>
208     export RPM_DIR=$HOME/freegisrpm
209     </programlisting>
210     </para>
211     </listitem>
212     <listitem>
213     <para>
214     Create $HOME/.rpmmacros:
215     This file sets general preferences and some
216     specific settings for signing packages.
217     If you don't have a GnuPG-key, you can skip
218     the signature settings i.e. drop the last 4 lines.
219     A signature becomes important when you want to
220     give away packages to third parties.
221     <programlisting>
222     <![CDATA[
223     %packager Name Lastname <[email protected]>
224    
225     %_topdir /home/mylogin/myrpm
226    
227     %_signature gpg
228     %_gpg_name Name Lastname
229     %_pgp_path ~/.gnupg
230     %_pgpbin /usr/bin/gpg
231     ]]>
232     </programlisting>
233     </para>
234     </listitem>
235     </itemizedlist>
236    
237     Now you can install any RPM source-package.
238     It's components are installed into the corresponding
239     subdirectories of your rpm-directory.
240     Essentially these are the sources (into directory SOURCES)
241     and the so-called spec-file which contains all build
242     instructions. The spec-file will go into the SPEC directory.
243     Example:
244     <literal>rpm --install Thuban-0.9.0-1.src.rpm</literal>
245     </para>
246    
247     <para>
248     Create install-package:
249     Go to the directory with the spec-files and rebuild the
250     package:
251     <programlisting>
252     cd $HOME/mypm/SPECS
253     rpm -bb thuban.spec
254     </programlisting>
255     Next, you will find the newly created package in
256     $HOME/myrpm/RPMS/i386.
257     If you build the package for another architecture than
258     i386, then the name of the directory has a corresponding name.
259     </para>
260     <para>
261     For documentation of RPM, either type
262     <literal>man rpm</literal> or <literal>rpm --help</literal>.
263     This will provide you with information on the various command
264     line options of RPM.
265     For more information see the
266     <ulink url="http://www.rpm.org/">homepage of RPM</ulink>.
267     </para>
268     </section>
269     </section> <!-- Intro - Installation - RPM-->
270    
271     <section><title>Win32 Systems</title>
272     <para>
273     A common installation package of Thuban for Win32
274     systems is available from the Thuban website download
275     section. This installation package is configured for
276     displaying file based vector data (Shapefiles). For the
277     display of raster data or the connection to spatial
278     databases additional steps are needed.
279     </para>
280     <para>
281     The required Python packages are listed and linked on
282     the download page as well. If you don't have Python
283     installed already, download the packages for Python,
284     wxPython for Python and the SQLite Python Libraries as
285     well as the Thuban package. Install all four packages
286     in the order: Python, wxPython, SQLite, Thuban. Follow
287     the installation instructions provided by the seperate
288     setups. The Thuban installation package will add an
289     entry in the menu folder you configured.
290     </para>
291     <section><title>Raster Data: Installation of GDAL</title>
292     <para>
293     Enabling the raster data features of Thuban is
294     straight forward. For the examples we assume that
295     Thuban has been installed under
296     <literal>C:\Thuban</literal>:
297     <itemizedlist>
298     <listitem>
299     <para>
300     Download the zip-archive <ulink
301     url="ftp://intevation.de/thuban/win2k/gdal-win2k.zip"
302     >gdal-win2k</ulink>.
303     </para></listitem>
304     <listitem><para>Extract the archive (e.g. with
305     <ulink
306     url="http://www.info-zip.org/pub/infozip/WiZ.html"
307     >WiZ (InfoZip)</ulink>) into the
308     <literal>C:\Thuban\Lib</literal>
309     directory of your Thuban installation.
310     </para>
311     </listitem>
312     <listitem>
313     <para>
314     Extent the <varname>PYTHONPATH</varname>
315     environment variable (in your Windows Control Panel)
316     to make the new libraries available for Thuban.
317     <programlisting>
318     %PYTHONPATH%;C:\Thuban\Lib\gdal;C:\Thuban\Lib\gdal\pymod
319     </programlisting>
320     </para>
321     </listitem>
322     <listitem>
323     <para>
324     Extent also the <varname>PATH</varname>
325     environment variable accordingly:
326     <programlisting>
327     %PATH%;C:\Thuban\Lib\gdal
328     </programlisting>
329     </para>
330     </listitem>
331     </itemizedlist>
332     After this installation steps Thuban is ready to
333     display raster data (e.g. the
334     <literal>island.tif</literal> from the Iceland Demo
335     data set.
336     </para>
337     </section> <!-- Win32: GDAL-->
338    
339     <section><title>Working with PostGIS: Installation of PsycoPG</title>
340     <para>
341     To access PostgreSQL/PostGIS spatial databases with
342     Thuban you have to install the PsycoPG package for
343     Windows:
344     <itemizedlist>
345     <listitem>
346     <para>
347     Download the zip-archive
348     <ulink
349     url="http://stickpeople.com/projects/python/win-psycopg/win-psycopg22.zip"
350     >win-psycopg22.zip</ulink>.
351     </para>
352     </listitem>
353     <listitem>
354     <para>
355     Extract the zip-archive into a directory either already
356     in your <varname>PYTHONPATH</varname> or extent your
357     <varname>PYTHONPATH</varname> variable to the directory
358     you have extracted the archive to.
359     </para>
360     </listitem>
361     </itemizedlist>
362     For installation and maintenance of spatial databases
363     we refer to the <ulink
364     url="http://postgis.refractions.net"
365     >PostGIS Homepage</ulink>.
366     </para>
367     </section> <!-- Win32: PsycoPG-->
368    
369     </section> <!-- Intro - Installation - Win32 -->
370     </section>
371    
372     <section><title>Internationalisierung</title>
373     <para>
374     Thuban ist mit Unterstützung für Internaionalisierung realisiert.
375     Bisher wurde Thuban in folgende Sprachen (neben der Basis Englisch) übersetzt:
376     <itemizedlist>
377     <listitem><para>Französisch</para></listitem>
378     <listitem><para>Deutsch</para></listitem>
379     <listitem><para>Italienisch</para></listitem>
380     <listitem><para>Portugiesisch (Brasilien)</para></listitem>
381     <listitem><para>Russisch</para></listitem>
382     <listitem><para>Spanisch</para></listitem>
383     </itemizedlist>
384     </para>
385    
386     <para>
387     Um die Internationalisierung auf POSIX Systemen (wie etwa GNU/Linux)
388     zu verwenden, muss die Umgebungsvariable LC_ALL entsprechend
389     gesetzt werden (z.B. LC_ALL=de_DE für Deutsch).
390     Prüfen Sie die Dokumentation zu Ihrem System für Details
391     und die unterstützten Einstellungen.
392     Normalweise haben Sie Ihre Sprache bereits mit der Installation
393     oder beim einloggen bereits vorausgewählt.
394     Trotzdem kann auch dann noch durch Setzen von LC_ALL auf
395     der Kommandozeile beim Aufruf von Thuban eine andere Sprache
396     gesetzt werden:
397     </para>
398     <programlisting>
399     LC_ALL=fr_FR thuban.py
400     </programlisting>
401    
402     <para>
403     MS Windows Benutzer müssen die Sprache über die Kontroll-Leiste einstellen
404     welche grundsätzlich alle Anwendungen beeinflusst.
405     </para>
406     </section>
407    
408     <section><title>Das Hauptfenster</title>
409     <para>
410     <figure><title>Das Hauptfenster</title>
411     <mediaobject>
412     <imageobject> <imagedata fileref="../images/1_2_mainwindow.png" format="PNG" scale="&imgscale;"/> </imageobject>
413     <imageobject> <imagedata fileref="./images/1_2_mainwindow.ps" format="EPS" scale="&imgscale;"/> </imageobject>
414     </mediaobject>
415     </figure>
416     </para>
417    
418     <para>
419     Das Hauptfenster stellt die aktuelle Karte dar. Hier kann der
420     Benutzer mit der Karte interagieren indem er die verschiednen
421     Werkzeuge anwendet.
422     </para>
423    
424     <para>
425     Die Legende auf der linken Seite zeigt eine Liste der aktuellen
426     Ebenen und alle dargestellten Klassifikations-Gruppen.
427     Bei diesem Beispiel haben alle Geo-Objekte Ebenen eine voreingestellte
428     Klassifizierung wie die jeweiligen Geo-Objekte in den einzelnen
429     Ebenen gezeichnet werden sollen.
430     Die Ebenen die weiter oben in der Liste dargestellt werden über
431     die darunter aufgelisteten gezeichnet.
432     Die Legende kann durch Anwahl des X in der oberen rechten Ecke
433     geschlossen werden.
434     Um die Legenden-Ansicht wieder zu öffnen, wählen Sie
435 jan 2313 <menuchoice>
436     <guimenu>Karte</guimenu>
437     <guimenuitem>Legende</guimenuitem>
438     </menuchoice>.
439     Das Legenden-Fenster ist lösbar. Das bedeutet, dass sie vom Hauptfenster
440     abgelöst und dann als eigenständiges Fenster
441     positioniert werden kann. Dies wird durch den kleinen Schalter
442     neben dem X gemacht. Erneutes Anwählen des Schalters läßt das
443     Legenden-Fenster wieder in das Hauptfenster integrieren.
444     </para>
445     <para>
446     Die Status-Leiste zeigt verschiedene Informationen jeweils
447     abhängig vom Kontext. Wählt der Benutzer einen Menüpunkt
448     dann wird in der Status-Leiste ein Hilfetext zu dem jeweiligen
449     Menüpunkt angezeigt.
450     Ist eines der Werkzeuge aktiviert, so wird in der Status-Leiste
451     die Position angegeben über der der Maus-Cursor auf der Karte
452     steht.
453     </para>
454     <para>
455     Die Werkzeugleiste erlaubt direkten Zugriff auf häufig
456     benötigte Werkzeuge.
457     Schwebt der Maus-Zeiger über einem Knopf wird eine Kurz-Info
458     über das jeweilige Werkzeug gegeben.
459     Folgende Werzeuge stehen zur Verfügung: Hineinzoomen,
460     Herauszoomen, Verschieben, Zur vollen Kartenausdehnung zoomen,
461     Zur vollen Ebenenausdehnung zoomen, Zur vollen Auswahlausdehnung zoomen,
462     Identifizieren, Labels hinzufügen/entfernen.
463     Alle Werkzeuge werden in diesem Handbuch noch detaillierter beschrieben.
464     </para>
465     </section>
466 jan 2309
467     </chapter>
468    
469     <chapter><title>Session Management</title>
470    
471 jan 2313 <section><title>Eine neue Session beginnen</title>
472     <para>
473     Eine neue Session wird gestartet über
474     <menuchoice>
475     <guimenu>Datei</guimenu>
476     <guimenuitem>Neue Session</guimenuitem>
477     </menuchoice>.
478     Falls bereits eine Session geladen ist und seit der letzten
479     Speicherung verändert wurde, so wird nun nachgefragt, ob
480     diese Session zunächst gespeichert werden soll.
481     Eine neue Session besteht aus einer leeren Karte
482     ohne Ebenen, Tabellen und Projektion.
483     </para>
484     </section>
485 jan 2309
486 jan 2313 <section><title>Eine Session öffnen</title>
487     <para>
488     Eine Session kann geöffnet werden über
489     <menuchoice>
490     <guimenu>Datei</guimenu>
491     <guimenuitem>Öffne Session</guimenuitem>
492     </menuchoice>.
493     Es wird ein Dateiauswahl-Dialog geöffnet um eine
494     Thuban Session Datei auszuwählen. Diese Dateien enden
495     auf <varname>.thuban</varname>. Wird eine Datei ausgewählt und mit
496     <guibutton>OK</guibutton> bestätigt, so wird die entsprechende
497     Session in Thuban geladen.
498 jan 2309
499 jan 2313 Ist bereits eine Session geladen und seit dem letzten Speichern modifiziert
500     worden, so wird nachgefragt, ob zunächst die alte Session gespeichert werden
501     soll.
502     </para>
503     </section>
504 jan 2309
505 jan 2313 <section><title>Eine Session speichern</title>
506     <para>
507     Eine Session kann gepsiechert werden über
508     <menuchoice>
509     <guimenu>Datei</guimenu>
510     <guimenuitem>Session Speichern</guimenuitem>
511     </menuchoice>.
512     Handelt es sich bei der aktuellen Session nicht um eine
513     neue und ungespeicherte, so wird die entsprechende Datei
514     mit den Daten der aktuellen Session überschrieben.
515     Im Falle einer neuen und noch nicht gespeicherten Session
516     wird ein Dateiauswahl-Dialog geöffnet um einen Namen
517     für die zu speicherende Session auszuwählen.
518     Thuban Session Dateien sollten mit der Endung
519     <varname>.thuban</varname> versehen werden.
520     Existiert bereits eine Datei mit dem gleichen Namen
521     wird der Benutzer gefragt ob diese überschrieben
522     oder ein neuer Name gewählt werden soll.
523     </para>
524     </section>
525 jan 2309
526 jan 2313 <section><title>Der Session Info-Baum</title>
527     <para>
528     <figure>
529     <title>Session Info-Baum</title>
530     <mediaobject>
531     <imageobject><imagedata fileref="../images/2_4_session_tree.png" format="PNG" scale="&imgscale;"/></imageobject>
532     <imageobject><imagedata fileref="./images/2_4_session_tree.eps" format="EPS" scale="&imgscale;"/></imageobject>
533     </mediaobject>
534     </figure>
535     </para>
536     <para>
537     Der Session Info-Baum ist hauptsächlich für Software-Entwickler gedacht
538     die an Thuban arbeiten.
539     Er stellt eine Reihe von internen Daten zur Session, der Karte, den
540     Ebenen usw. dar. Er wird geöffnet über
541     <menuchoice>
542     <guimenu>Datei</guimenu>
543     <guimenuitem>Session Baum</guimenuitem>
544     </menuchoice>.
545     </para>
546     </section>
547 jan 2309 </chapter>
548    
549 jan 2369 <chapter><title>Karten Management</title>
550 jan 2309 <para>
551 jan 2369 Die Karte besteht aus eine Anzahl Ebenen wobei jede Ebene einen
552     Datensatz mit bestimtem Typ repräsentiert. Mit Interaktion auf der
553     Karte kann ein Benutzer die Daten visuell erforschen.
554 jan 2309 </para>
555     <para>
556 jan 2369 Die Karte kann einen Namen haben der dann in der Kopfzeile des
557     Thuban Fensters auftaucht. Der Kartenname kann geändert werden
558     über
559 jan 2309 <menuchoice>
560 jan 2369 <guimenu>Karte</guimenu>
561     <guimenuitem>Umbennen</guimenuitem>
562 jan 2309 </menuchoice>.
563     </para>
564     <para>
565     <inlinemediaobject>
566     <imageobject>
567     <imagedata fileref="../images/3_rename_map.png" format="PNG" scale="&imgscale;"/>
568     </imageobject>
569     <imageobject>
570     <imagedata fileref="./images/3_rename_map.eps" format="EPS" scale="&imgscale;"/>
571     </imageobject>
572 jan 2369 <textobject> <phrase>Karte umbennen</phrase> </textobject>
573 jan 2309 </inlinemediaobject>
574     </para>
575    
576 jan 2369 <section><title>Hinzufügen und Entfernen von Ebenen</title>
577     <para>
578     Es gibt drei Typen von Ebenen aus denen eine Karte besteht:
579     Shape Ebene, Datenbank Ebene und Bildebene.
580     Shape Ebenen sind im Shapefile Format gespeichert welches
581     weit verbreitet für die Speicherung von geografischen Objekten
582     genutzt wird.
583     Die Dateien haben die Endung ``.shp''. Mit der eigentlichen Shape
584     Datei ist eine Datenbank Datei welche die Attribut-Daten zu dem
585     Shapefile enthält. Diese Datenbank Datei verwendet das dBase Format
586     und hat die Endung ``.dbf''. Beide Dateien müssen den selben
587     Basisnamen haben. So gehören zum Beispiel die Dateien
588     strassen.shp und strassen.dbf zusammen.
589     </para>
590 jan 2309 <itemizedlist>
591     <listitem>
592     <para>
593 jan 2369 Shape Ebenen können zur Karte hinzugefügt werden mit
594 jan 2309 <menuchoice>
595 jan 2369 <guimenu>Karte</guimenu>
596     <guimenuitem>Ebene hinzufügen</guimenuitem>
597 jan 2309 </menuchoice>.
598 jan 2369 Zunächst werden im Dateiauswahl Dialog nur die ``.shp'' Dateien
599     angezeigt, was für die Auswahl vollkommen ausreicht.
600     Falls Sie aber auf Ansicht aller Dateien umschalten, und dann
601     einer der assoziierten Dateien (z.B. mit der Endung ``.dbf'')
602     auswählen, so verwendet Thuban den Basisnamen um die entsprechende
603     Shape Datei zu laden,
604     </para>
605 jan 2309 <para>
606 jan 2369 Der Dateidialog für Shape Dateien erlaubt es auch, viele
607     Dateien gleichzeitig auszuwählen. Verwenden Sie dafür
608     die Umschalt-Taste gleichzeitig mit der linken Maustaste um
609     die Auswahl zu erweitern.
610     </para>
611 jan 2309 </listitem>
612    
613     <listitem>
614 jan 2369 <para>Datenbankebenen können zu Karte hinzugefügt werden mit
615 jan 2309 <menuchoice>
616 jan 2369 <guimenu>Karte</guimenu>
617     <guimenuitem>Datenbankebene hinzufügen</guimenuitem>
618 jan 2309 </menuchoice>.
619 jan 2369 Es wird ein Duialog mit zwei Listen geöffnet.
620     Die linke Liste zeigt alle derzeit offenen Datenbankverbindungen dieser
621     Session an. Eine Liste der verfügbaren Ebenen aus einer Datenbankverbindung
622     wird steht auf der rechten Seite. Aus dieser Liste können Sie eine
623     beliebige Ebene zum Öffnen auswählen. Der Dialog wird dabach
624     automatisch beendet.
625 jan 2309 </para>
626     <para>
627 jan 2369 Siehe auch Anhang ``Mit PostGIS arbeiten'' für weitere Details.
628 jan 2309 </para>
629     </listitem>
630    
631     <listitem>
632     <para>
633 jan 2369 Bildebenen können zur Karte hinzugefügt werden mit
634 jan 2309 <menuchoice>
635 jan 2369 <guimenu>Karte</guimenu>
636     <guimenuitem>Bildebene hinzufügen</guimenuitem>
637 jan 2309 </menuchoice>.
638 jan 2369 Es ist wichtig, dass eine korrekte Bilddatei ausgewählt für
639     die auch geographische Daten (Projektions) vorliegen.
640     Diese Daten können in die Bilddatei eingebettet sein oder
641     als separate Datei vorliegen. Können diese Daten nicht
642     gefunden werden, so wird Thuban einen Fehler melden.
643 jan 2309 </para>
644     </listitem>
645     </itemizedlist>
646     </section>
647    
648     <section><title>Navigation</title>
649     <para>
650 jan 2369 Die Karte kann erforscht werden indem die Navigationswerkzeuge
651     aus der Werkzeugleiste oder über das Menü
652     <menuchoice><guimenu>Karte</guimenu></menuchoice> ausgewählt werden.
653 jan 2309 </para>
654     <itemizedlist>
655     <listitem>
656     <para>
657 jan 2369 Das ZoomIn Werkzeug
658 jan 2309 <inlinemediaobject>
659     <imageobject>
660     <imagedata fileref="../images/3_2_zoomin.png" format="PNG" scale="&imgscale;"/>
661     </imageobject>
662     <imageobject>
663     <imagedata fileref="./images/3_2_zoomin.eps" format="EPS" scale="&imgscale;"/>
664     </imageobject>
665 jan 2369 <textobject> <phrase>ZoomIn Werkzeug</phrase> </textobject>
666 jan 2309 </inlinemediaobject>
667 jan 2369 vergrößert einen Bereich aus der Karte. Ein einmaliges Klicken auf
668     die Karte vergrößert die Karte um das Doppelte und zentriert auf den
669     angewählten Punkt. Klicken und Ziehen selektiert einen Bereich
670     der dann so vergrößert wird, dass er das Fenster ausfüllt.
671 jan 2309 </para>
672     </listitem>
673     <listitem>
674     <para>
675 jan 2369 Das ZoomOut Werkzeug
676 jan 2309 <inlinemediaobject>
677     <imageobject>
678     <imagedata fileref="../images/3_2_zoomout.png" format="PNG" scale="&imgscale;"/>
679     </imageobject>
680     <imageobject>
681     <imagedata fileref="./images/3_2_zoomout.eps" format="EPS" scale="&imgscale;"/>
682     </imageobject>
683 jan 2369 <textobject> <phrase>ZoomOut Werkzeug</phrase> </textobject>
684 jan 2309 </inlinemediaobject>
685 jan 2369 verkleinert die Karte, so dass ein größerer Bereich zu sehen ist.
686     Ein einzelnen Klick verkleinert die Karte um Faktor 2.
687     Klicken und Ziehen selektiert einen Bereich in den die gesamte sichtbare
688     Karte im Fenster hineinverkleinert wird.
689 jan 2309 </para>
690     </listitem>
691     <listitem>
692     <para>
693     The Pan tool
694     <inlinemediaobject>
695     <imageobject>
696     <imagedata fileref="../images/3_2_pan.png" format="PNG" scale="&imgscale;"/>
697     </imageobject>
698     <imageobject>
699     <imagedata fileref="./images/3_2_pan.eps" format="EPS" scale="&imgscale;"/>
700     </imageobject>
701     <textobject> <phrase>Pan Tool</phrase> </textobject>
702     </inlinemediaobject>
703     allows the user to move the map around by clicking and dragging.
704     </para>
705     </listitem>
706     <listitem>
707     <para>
708     The Full Extent tool
709     <inlinemediaobject>
710     <imageobject>
711     <imagedata fileref="../images/3_2_fullextent.png" format="PNG" scale="&imgscale;"/>
712     </imageobject>
713     <imageobject>
714     <imagedata fileref="./images/3_2_fullextent.eps" format="EPS" scale="&imgscale;"/>
715     </imageobject>
716     <textobject> <phrase>Full Extent Tool</phrase> </textobject>
717     </inlinemediaobject>
718     rescales the viewable region so that the entire map is visible.
719     </para>
720     </listitem>
721     <listitem>
722     <para>
723     The Full Layer Extent tool
724     <inlinemediaobject>
725     <imageobject>
726     <imagedata fileref="../images/3_2_fulllayerextent.png" format="PNG" scale="&imgscale;"/>
727     </imageobject>
728     <imageobject>
729     <imagedata fileref="./images/3_2_fulllayerextent.eps" format="EPS" scale="&imgscale;"/>
730     </imageobject>
731     <textobject> <phrase>Full Layer Extent Tool</phrase> </textobject>
732     </inlinemediaobject>
733     rescales the viewable region so that the currently selected
734     layer fits within the window. If no layer is selected this button
735     will be disabled.
736     </para>
737     </listitem>
738     <listitem>
739     <para>
740     The Full Shape Extent tool
741     <inlinemediaobject>
742     <imageobject>
743     <imagedata fileref="../images/3_2_fullshapeextent.png" format="PNG" scale="&imgscale;"/>
744     </imageobject>
745     <imageobject>
746     <imagedata fileref="./images/3_2_fullshapeextent.eps" format="EPS" scale="&imgscale;"/>
747     </imageobject>
748     <textobject> <phrase>Full Shape Extent Tool</phrase> </textobject>
749     </inlinemediaobject>
750     rescales the viewable region so that the currently selected
751     shape fits within the window. If the shape is a point, it is
752     centered and the map is zoomed all the way in. If no shape is
753     selected this button will be disabled. This feature is especially
754     helpful when identifying an object related to a selected record
755     in a tableview (see below).
756    
757     </para>
758     </listitem>
759     </itemizedlist>
760     </section>
761    
762     <section><title>Object Identification</title>
763     <para>
764     Objects on the map can be identified using the Identify tool
765     <inlinemediaobject>
766     <imageobject>
767     <imagedata fileref="../images/3_3_identify.png" format="PNG" scale="&imgscale;"/>
768     </imageobject>
769     <imageobject>
770     <imagedata fileref="./images/3_3_identify.eps" format="EPS" scale="&imgscale;"/>
771     </imageobject>
772     <textobject> <phrase>Identify Tool</phrase> </textobject>
773     </inlinemediaobject>.
774     Clicking on an object selects that object and opens a dialog which
775     shows all the table attributes for that object. Any current selection
776     is lost. Objects on the map are typically shapes and this document
777     will often refer to objects as shapes.
778     </para>
779     </section>
780    
781     <section><title>Object Labeling</title>
782     <para>
783     Objects can be labeled using the Label tool
784     <inlinemediaobject>
785     <imageobject>
786     <imagedata fileref="../images/3_3_label.png" format="PNG" scale="&imgscale;"/>
787     </imageobject>
788     <imageobject>
789     <imagedata fileref="./images/3_3_label.eps" format="EPS" scale="&imgscale;"/>
790     </imageobject>
791     <textobject> <phrase>Label Tool</phrase> </textobject>
792     </inlinemediaobject>.
793     Clicking on an object selects that object and opens a dialog which
794     displays the table attributes for that object. An attribute can
795     be selected to be the label on the map. The label will be placed
796     at the center of the shape. Clicking on an object that already has
797     a label will remove the label.
798     </para>
799     </section>
800    
801     <section><title>The Legend</title>
802     <para>
803     <inlinemediaobject>
804     <imageobject>
805     <imagedata fileref="../images/3_5_legend.png" format="PNG" scale="&imgscale;"/>
806     </imageobject>
807     <imageobject>
808     <imagedata fileref="./images/3_5_legend.eps" format="EPS" scale="&imgscale;"/>
809     </imageobject>
810     <textobject> <phrase>Legend</phrase> </textobject>
811     </inlinemediaobject>
812     </para>
813     <para>
814     The Legend provides an overview of the layers in the map. Layers
815     that appear higher in the legend will appear ``closer'' to the user.
816     If a layer supports classification (currently, only shape layers
817     have this feature) then the classification groups will be shown
818     below each layer. The properties for each group are also displayed
819     with a small graphic. Polygon layers appear as rectangles, lines
820     appear as curved lines, and points appear as circles.
821     </para>
822     <para>
823     Along the top of the legend is a toolbar which allows quick access
824     to some of the layer manipulation options under
825     <menuchoice><guimenu>Map</guimenu></menuchoice>.
826     </para>
827    
828     <itemizedlist>
829     <listitem>
830     <para>
831     The Move Layer to Top tool
832     <inlinemediaobject>
833     <imageobject>
834     <imagedata fileref="../images/3_5_totop.png" format="PNG" scale="&imgscale;"/>
835     </imageobject>
836     <imageobject>
837     <imagedata fileref="./images/3_5_totop.eps" format="EPS" scale="&imgscale;"/>
838     </imageobject>
839     <textobject> <phrase>Move Layer to Top</phrase> </textobject>
840     </inlinemediaobject> raises the selected layer to the top of the map.
841     </para>
842     </listitem>
843     <listitem>
844    
845     <para>
846     The Move Layer Up tool
847     <inlinemediaobject>
848     <imageobject>
849     <imagedata fileref="../images/3_5_moveup.png" format="PNG" scale="&imgscale;"/>
850     </imageobject>
851     <imageobject>
852     <imagedata fileref="./images/3_5_moveup.eps" format="EPS" scale="&imgscale;"/>
853     </imageobject>
854     <textobject> <phrase>Move Layer Up</phrase> </textobject>
855     </inlinemediaobject> raises the selected layer one level.
856     </para>
857     </listitem>
858     <listitem>
859    
860     <para>
861     The Move Layer Down tool
862     <inlinemediaobject>
863     <imageobject>
864     <imagedata fileref="../images/3_5_movedown.png" format="PNG" scale="&imgscale;"/>
865     </imageobject>
866     <imageobject>
867     <imagedata fileref="./images/3_5_movedown.eps" format="EPS" scale="&imgscale;"/>
868     </imageobject>
869     <textobject> <phrase>Move Layer Down</phrase> </textobject>
870     </inlinemediaobject> lowers the selected layer one level.
871     </para>
872    
873     </listitem>
874     <listitem>
875     <para>
876     The Move Layer to Bottom tool
877     <inlinemediaobject>
878     <imageobject>
879     <imagedata fileref="../images/3_5_tobottom.png" format="PNG" scale="&imgscale;"/>
880     </imageobject>
881     <imageobject>
882     <imagedata fileref="./images/3_5_tobottom.eps" format="EPS" scale="&imgscale;"/>
883     </imageobject>
884     <textobject> <phrase>Move Layer to Bottom</phrase> </textobject>
885     </inlinemediaobject> lowers the selected layer to the bottom of the map.
886     </para>
887    
888     </listitem>
889     <listitem>
890     <para>
891     The Visible tool
892     <inlinemediaobject>
893     <imageobject>
894     <imagedata fileref="../images/3_5_visible.png" format="PNG" scale="&imgscale;"/>
895     </imageobject>
896     <imageobject>
897     <imagedata fileref="./images/3_5_visible.eps" format="EPS" scale="&imgscale;"/>
898     </imageobject>
899     <textobject> <phrase>Visible</phrase> </textobject>
900     </inlinemediaobject> shows the selected layer in the map if it was
901     hidden.
902     </para>
903    
904     </listitem>
905     <listitem>
906     <para>
907     The Invisible tool
908     <inlinemediaobject>
909     <imageobject>
910     <imagedata fileref="../images/3_5_invisible.png" format="PNG" scale="&imgscale;"/>
911     </imageobject>
912     <imageobject>
913     <imagedata fileref="./images/3_5_invisible.eps" format="EPS" scale="&imgscale;"/>
914     </imageobject>
915     <textobject> <phrase>Invisible</phrase> </textobject>
916     </inlinemediaobject> hides the selected layer in the map.
917     </para>
918    
919     </listitem>
920     <listitem>
921     <para>
922     The Properties tool
923     <inlinemediaobject>
924     <imageobject>
925     <imagedata fileref="../images/3_5_props.png" format="PNG" scale="&imgscale;"/>
926     </imageobject>
927     <imageobject>
928     <imagedata fileref="./images/3_5_props.eps" format="EPS" scale="&imgscale;"/>
929     </imageobject>
930     <textobject> <phrase>Properties</phrase> </textobject>
931     </inlinemediaobject> opens the layer's properties dialog box.
932     Double-clicking on a layer or a group of a layer will open the
933     properties dialog for that layer.
934     </para>
935     </listitem>
936     </itemizedlist>
937    
938     <para>
939     The most used layer related actions are also available from a
940     popup menu. It is raised when a layer is clicked with the right mouse
941     button.
942     </para>
943    
944     <para>
945     <figure>
946     <title>Layer Popup Menu</title>
947     <mediaobject>
948     <imageobject><imagedata fileref="../images/3_5_popup_menu.png" format="PNG" scale="&imgscale;"/></imageobject>
949     <imageobject><imagedata fileref="./images/3_5_popup_menu.eps" format="EPS" scale="&imgscale;"/></imageobject>
950     </mediaobject>
951     </figure>
952     </para>
953    
954     <para>
955     Along the bottom of the legend is the scalebar. The scalebar
956     will be available if there are any layers and the map has a
957     projection set.
958     </para>
959     </section>
960    
961     <section><title>Exporting</title>
962     <para>
963     Under Windows, maps can be exported in Enhanced Metafile format
964     (<varname>.wmf</varname>)
965     from
966     <menuchoice>
967     <guimenu>Map</guimenu>
968     <guimenuitem>Export</guimenuitem>
969     </menuchoice> for use in reports, presentations, or further
970     modification. The current map view, legend, and, if available,
971     scalebar are exported. Under other platforms this option is not
972     available. Clicking this menu item open a file selection dialog
973     that lets the user select a location to export the map.
974     </para>
975     </section>
976    
977     <section><title>Printing</title>
978     <para>
979     The map can be printed using
980     <menuchoice>
981     <guimenu>Map</guimenu>
982     <guimenuitem>Print</guimenuitem>
983     </menuchoice>. The current map view, legend, and, if available,
984     scalebar are printed. A standard printing dialog will open allowing
985     the user to configure the printer. This dialog will differ depending
986     on which platform Thuban is running.
987     </para>
988     </section>
989    
990     </chapter>
991    
992     <chapter><title>Layer Management</title>
993     <para>
994     </para>
995    
996     <section><title>Types of Layers</title>
997     <para>
998     There are three types of layers supported by Thuban: shape layers,
999     database layers and
1000     image layers. Shape layers consist of vector based shapes with
1001     geo-referenced coordinates. There are three types of supported
1002     shapes: polygons, lines (arc), and points. Database layers are similar
1003     to shape layers but loaded from a database instead of the file system.
1004     Image layers can be any image
1005     file format supported by the Geo-spatial Data Abstraction Library
1006     (GDAL). The images must have geographic
1007     coordinate data either embedded within the file or in a separate
1008     file that is in the same directory as the image file. GeoTIFF files
1009     work very well with Thuban and were designed specifically to be image
1010     layers in GIS programs.
1011     </para>
1012     <para>
1013     All actions in the
1014     <menuchoice>
1015     <guimenu>Layer</guimenu>
1016     </menuchoice> menu act on the currently selected layer in the legend.
1017     </para>
1018     </section>
1019    
1020     <section><title>Properties</title>
1021     <para>
1022     To view the properties for a layer it must first be selected in the
1023     legend. The menu option
1024     <menuchoice>
1025     <guimenu>Layer</guimenu>
1026     <guimenuitem>Properties</guimenuitem>
1027     </menuchoice> opens a dialog that displays a layer's properties.
1028     All layers have a title which can be modified in the text field
1029     provided. The type of layer is also shows. If the type is a type
1030     of shape (polygon, arc, point) the classification table will be
1031     shown. Image layers have no other properties other than title
1032     and type.
1033     </para>
1034     <para>
1035     <figure>
1036     <title>Properties Window</title>
1037     <mediaobject>
1038     <imageobject><imagedata fileref="../images/4_2_layer_properties.png" format="PNG" scale="&imgscale;"/></imageobject>
1039     <imageobject><imagedata fileref="./images/4_2_layer_properties.eps" format="EPS" scale="&imgscale;"/></imageobject>
1040     </mediaobject>
1041     </figure>
1042     </para>
1043     <para>
1044     <figure>
1045     <title>Properties Window</title>
1046     <mediaobject>
1047     <imageobject><imagedata fileref="../images/4_2_raster_layer_properties.png" format="PNG" scale="&imgscale;"/></imageobject>
1048     <imageobject><imagedata fileref="./images/4_2_raster_layer_properties.eps" format="EPS" scale="&imgscale;"/></imageobject>
1049     </mediaobject>
1050     </figure>
1051     </para>
1052     </section>
1053    
1054     <section><title>Visibility</title>
1055     <para>
1056     Sometimes it is not desirable to view all layers at the same time.
1057     Some layers may take a long time to draw and so while navigating
1058     around the map the user may not want to wait for the map to redraw
1059     all the layers each time the map is changed. Each layer can be
1060     independently turned on or off using the
1061     <menuchoice>
1062     <guimenu>Layer</guimenu>
1063     <guimenuitem>Show</guimenuitem>
1064     </menuchoice>
1065     or
1066     <menuchoice>
1067     <guimenu>Layer</guimenu>
1068     <guimenuitem>Hide</guimenuitem>
1069     </menuchoice> options respectively.
1070     </para>
1071     </section>
1072    
1073     <section><title>Duplication</title>
1074     <para>
1075     Layers and all their properties, including classifications, can
1076     be duplicated using
1077     <menuchoice>
1078     <guimenu>Layer</guimenu>
1079     <guimenuitem>Duplicate</guimenuitem>
1080     </menuchoice>. Duplicating a layer is useful if the user wishes
1081     to model a layer in several different ways. Even though the layers
1082     overlap, by carefully selecting the shape properties it is possible
1083     to display several pieces of information at once. For example, one
1084     copy of a roads layer may be classified on a length property and
1085     another copy may be classified on a type property. If the length
1086     property was expressed with color and the type property expressed
1087     with line thickness then it would be possible to view both
1088     classifications by placing the type property copy over the
1089     length property copy.
1090     </para>
1091     </section>
1092    
1093     </chapter>
1094    
1095     <chapter><title>Layer Classifications</title>
1096     <para>
1097     A layer classification is a way of assigning drawing properties to
1098     groups of shapes based on attributes stored in the layer's table.
1099     Only layer's with shapes can have a classification; image layers
1100     cannot be classified.
1101     </para>
1102     <para>
1103     A classification consists of a number of groups, each group
1104     having a value or range of values to match against, and symbol
1105     properties which control how a shape is drawn on the map. The user
1106     selects which field in the table is used by the classification and
1107     when the map is drawn the value for that field for each shape is
1108     compared with each group's value. The properties of the first group
1109     to match are used to draw the shape. This allows the user to get a
1110     visual impression of not only how the data is laid out but also what
1111     kind of data lies where.
1112     </para>
1113     <para>
1114     A layer always has a classification. When a new layer is added to the
1115     map, a default classification is created with the DEFAULT group. This
1116     group cannot be removed but can be hidden (see below). Every shape in the
1117     layer, regardless of its attributes, will match this group if no other
1118     group matches.
1119     </para>
1120    
1121     <section><title>Editing Classifications</title>
1122     <para>
1123     A layer's classification can be modified under the properties dialog
1124     (<menuchoice>
1125     <guimenu>Layer</guimenu>
1126     <guimenuitem>Properties</guimenuitem>
1127     </menuchoice>). The layer's classification field can be set to None,
1128     which simply assigns a DEFAULT group to the classification. No new
1129     groups can be added to the classification if the field is None.
1130     The user must first select a field to classify on. New groups can
1131     be added to the classification with the <guibutton>Add</guibutton>
1132     button.
1133     </para>
1134     <para>
1135     To apply the changes to the map the user can click
1136     either <guibutton>Try</guibutton> or <guibutton>OK</guibutton>.
1137     <guibutton>Try</guibutton> will not close the dialog box, allowing
1138     the user to see how the classification changes the map.
1139     <guibutton>Revert</guibutton> will undo the last classification applied
1140     to the map. <guibutton>OK</guibutton> will commit the changes and
1141     close the dialog. The user will be unable to undo the changes.
1142     <guibutton>Close</guibutton> simply closes the dialog box. If any
1143     changes have not been applied with <guibutton>Try</guibutton> the
1144     changes will not be applied to the map.
1145     </para>
1146     <para>
1147     <figure>
1148     <title>Properties Window</title>
1149     <mediaobject>
1150     <imageobject><imagedata fileref="../images/5_classification.png" format="PNG" scale="&imgscale;"/></imageobject>
1151     <imageobject><imagedata fileref="./images/5_classification.eps" format="EPS" scale="&imgscale;"/></imageobject>
1152     </mediaobject>
1153     </figure>
1154     </para>
1155     <para>
1156     The order of the groups in the classification is significant
1157     except for the DEFAULT group, which remains at the top. When shapes
1158     are matched against groups the matching begins at the first group
1159     after the DEFAULT group so that groups higher in the list will
1160     be checked first. Matching for a
1161     given shape will stop at the first group that matches. The user can
1162     use <guibutton>Move Up</guibutton> and <guibutton>Move Down</guibutton>
1163     to change the order of the groups. The DEFAULT group will always
1164     match a shape that hasn't matched another group.
1165     </para>
1166     <section><title>Visible</title>
1167     <para>
1168     The Visible column has check-boxes that determine whether a
1169     classification group will be displayed in the legend. This is
1170     useful if the user knows that the groups completely cover
1171     the data set and don't want the DEFAULT group to be displayed
1172     in the legend and on a printout.
1173     </para>
1174     </section>
1175     <section><title>Symbols</title>
1176     <para>
1177     Each type of shape has its own type of symbol. Thuban supports three
1178     types of shapes: polygons, lines, and points. Polygons and points
1179     have outline and fill color, while lines have only line color. Each
1180     group has associated symbol properties. To edit the symbol
1181     properties for a group the user can double click on the Symbol
1182     column or select a group and click the
1183     <guibutton>Edit Symbol</guibutton> button.
1184     </para>
1185     </section>
1186     <section><title>Value</title>
1187     <para>
1188     The Value column of the classification table is the value that will
1189     be matched when the map is being drawn. The type of data that can
1190     entered into this field depends on the type of data of the
1191     classification field.
1192     </para>
1193     <para>
1194     If the field is of type Text, anything entered
1195     into the field is valid. The text will be compared literally to the
1196     value of the shape attribute, including case sensitivity.
1197     If the type is Integer, then any valid integer may be entered. In
1198     addition, with special syntax, a range of values can be entered.
1199     A range from <varname>start</varname> to <varname>end</varname>
1200     inclusive is specified like this: <literal>[start;end]</literal>.
1201     The exclusive range is specified like this:
1202     <literal>]start;end[</literal>. Ranges can include infinity like
1203     this: <literal>[-oo;oo]</literal>. Field types can also be of type
1204     Decimal. They represent any rational number and can be used in
1205     ranges as well.
1206     </para>
1207     </section>
1208     <section><title>Label</title>
1209     <para>
1210     By default, the text that is displayed for a group in the legend
1211     is the value for that group. The label can substitute a more
1212     descriptive term in the legend.
1213     </para>
1214     </section>
1215     </section>
1216    
1217     <section><title>Generating Classes</title>
1218     <para>
1219     <figure>
1220     <title>Generate Class</title>
1221     <mediaobject>
1222     <imageobject><imagedata fileref="../images/5_3_genclass.png" format="PNG" scale="&imgscale;"/></imageobject>
1223     <imageobject><imagedata fileref="./images/5_3_genclass.eps" format="EPS" scale="&imgscale;"/></imageobject>
1224     </mediaobject>
1225     </figure>
1226     </para>
1227     <para>
1228     Creating a classification by hand can be tedious.
1229     Thuban, therefore, provides a means of generating an entire
1230     classification at once while still giving the user control over
1231     how it appears. Clicking <guibutton>Generate Class</guibutton>
1232     opens the <varname>Generate Classification</varname> dialog.
1233     Under the <varname>Generate</varname> pull down there are at most
1234     three different ways to generate classifications:
1235     Unique Values, Uniform Distribution, and Quantiles. Some options
1236     may not be available if the data type for the field does not
1237     support them. For instance, <varname>Uniform Distribution</varname>
1238     doesn't make sense for a Text field.
1239     </para>
1240     <para>
1241     For every way of generating a classification, a color scheme must
1242     be selected. Thuban provides several different color schemes that
1243     affect how the group properties change over the classification.
1244     It may be desirable that only certain properties change over the
1245     classification. If the shape type is a polygon or a point then
1246     the <guibutton>Fix Border Color</guibutton> option will be available.
1247     This allows the user to select a border color for all classification
1248     groups.
1249     It is also possible to create a custom color scheme. Selecting
1250     this option will display two symbols: the one of the left has the
1251     properties of the first group and the one on the right has the
1252     properties of the last group. Thuban will interpolate between these
1253     two properties to generate the other groups.
1254     <figure>
1255     <title>Custom Color Scheme</title>
1256     <mediaobject>
1257     <imageobject><imagedata fileref="../images/5_2_custom_ramp.png" format="PNG" scale="&imgscale;"/></imageobject>
1258     <imageobject><imagedata fileref="./images/5_2_custom_ramp.eps" format="EPS" scale="&imgscale;"/></imageobject>
1259     </mediaobject>
1260     </figure>
1261     </para>
1262     <para>
1263     The Unique Values option lets the user select specific values that
1264     appear in the table. Clicking <guibutton>Retrieve From Table</guibutton>
1265     searches the table for all unique values and displays them in the
1266     list on the left. Items can be selected and moved to the list on the
1267     right. Each list can be sorted or reversed for easier searching.
1268     The classification that is generated will be in the same order as
1269     the list on the right.
1270     <figure>
1271     <title>Unique Values</title>
1272     <mediaobject>
1273     <imageobject><imagedata fileref="../images/5_2_unique_values.png" format="PNG" scale="&imgscale;"/></imageobject>
1274     <imageobject><imagedata fileref="./images/5_2_unique_values.eps" format="EPS" scale="&imgscale;"/></imageobject>
1275     </mediaobject>
1276     </figure>
1277     </para>
1278     <para>
1279     The Uniform Distribution option creates a user specified number of
1280     groups of ranges such that each range covers equal intervals. The
1281     minimum and maximum values can automatically be retrieved from the
1282     table by clicking <guibutton>Retrieve From Table</guibutton>. The
1283     stepping is how large each interval is. Adjusting this value will
1284     automatically recalculate how many groups is appropriate.
1285     <figure>
1286     <title>Uniform Distribution</title>
1287     <mediaobject>
1288     <imageobject><imagedata fileref="../images/5_2_uniform_dist.png" format="PNG" scale="&imgscale;"/></imageobject>
1289     <imageobject><imagedata fileref="./images/5_2_uniform_dist.eps" format="EPS" scale="&imgscale;"/></imageobject>
1290     </mediaobject>
1291     </figure>
1292     </para>
1293     <para>
1294     The Quantiles option generates ranges based on the number of items
1295     in the table. For example, by specifying five groups Thuban will
1296     generate five groups with appropriate ranges such that 20% of the table
1297     data is in each group. If it is impossible to generate exact
1298     groupings, Thuban will issue a warning but allow the user to continue.
1299     <figure>
1300     <title>Quantiles</title>
1301     <mediaobject>
1302     <imageobject><imagedata fileref="../images/5_2_quantiles.png" format="PNG" scale="&imgscale;"/></imageobject>
1303     <imageobject><imagedata fileref="./images/5_2_quantiles.eps" format="EPS" scale="&imgscale;"/></imageobject>
1304     </mediaobject>
1305     </figure>
1306     </para>
1307     </section>
1308     </chapter>
1309    
1310     <chapter><title>Projection Management</title>
1311     <para>
1312     Projections control how the geographic data is displayed on the screen.
1313     If multiple layers are loaded into Thuban where the geographic data
1314     is in a different projection system, then the user must specify a
1315     projection for each layer. The user must also tell Thuban which
1316     projection the map is in. This can be the same as the layers or a different
1317     projection in which case the layers are reprojected into that space.
1318     The map projection can be set using
1319     <menuchoice>
1320     <guimenu>Map</guimenu>
1321     <guimenuitem>Projection</guimenuitem>
1322     </menuchoice> and the layer projection can be set using
1323     <menuchoice>
1324     <guimenu>Layer</guimenu>
1325     <guimenuitem>Projection</guimenuitem>
1326     </menuchoice>.
1327     <figure>
1328     <title>Projection Window</title>
1329     <mediaobject>
1330     <imageobject><imagedata fileref="../images/6_projection.png" format="PNG" scale="&imgscale;"/></imageobject>
1331     <imageobject><imagedata fileref="./images/6_projection.eps" format="EPS" scale="&imgscale;"/></imageobject>
1332     </mediaobject>
1333     </figure>
1334     </para>
1335     <para>
1336     Thuban is distributed with a sample collection of projections and the
1337     set of coordinate systems as used by the EPSG
1338     (European Petroleum Survey Group). This quite large set is only displayed
1339     if activated by the according checkbox. The set falls into two parts:
1340     deprecated lists all projections which are no longer part of the
1341     EPSG data base.
1342     </para>
1343     <para>
1344     The
1345     user can create new projections and make them available to all
1346     future Thuban sessions. They may also be exported and imported so
1347     that custom projections can be distributed.
1348     </para>
1349     <section><title>Selecting a Projection</title>
1350     <para>
1351     The available projections are listed on the left. If the layer
1352     or map already has a projection it will initially be highlighted
1353     and will end with <varname>(current)</varname>. Selecting
1354     <varname>&lt;None&gt;</varname> will cause Thuban to use the data as
1355     it appears in the source file and will not use a projection.
1356     </para>
1357     </section>
1358     <section><title>Editing a Projection</title>
1359     <para>
1360     Whenever a projection is selected from the list its properties
1361     are displayed on the right. These properties can be changed
1362     and the changes saved to the selected projection using
1363     <guibutton>Update</guibutton>. Only a projection that comes
1364     from a file can be updated, so if the current layer's projection
1365     is selected, <guibutton>Update</guibutton> will be disabled.
1366     <guibutton>Add to List</guibutton> adds the projection to the
1367     list of available projections as a new entry, and thus makes it
1368     available to future Thuban sessions. Clicking <guibutton>New</guibutton>
1369     will create an entirely new, empty projection. The
1370     <guibutton>Remove</guibutton> button will permanently remove a
1371     projection from the list of available projections.
1372     </para>
1373     <para>
1374     To apply the selected projection to the map the user can click
1375     either <guibutton>Try</guibutton> or <guibutton>OK</guibutton>.
1376     <guibutton>Try</guibutton> will not close the dialog box, allowing
1377     the user to see how the projeciton changes the map.
1378     <guibutton>Revert</guibutton> will undo the last projection applied
1379     to the map. <guibutton>OK</guibutton> will commit the changes and
1380     close the dialog. The user will be unable to undo the changes.
1381     <guibutton>Close</guibutton> simply closes the dialog box. If no
1382     selection has been applied with <guibutton>Try</guibutton> the
1383     selection will not be applied to the map.
1384     </para>
1385     </section>
1386     <section><title>Importing/Exporting Projections</title>
1387     <para>
1388     The projections that appear in the list of available projections
1389     can be exported to another file that the user chooses. By selecting
1390     one or more projections and clicking <guibutton>Export</guibutton>
1391     the user will be able to select a file in which to store those
1392     projections.
1393     The file can then be distributed to other Thuban users. To import
1394     a projection file the user can click <guibutton>Import</guibutton>.
1395     The imported projections are added to the list and are then available
1396     to the current session and any future Thuban sessions.
1397     </para>
1398     </section>
1399     </chapter>
1400    
1401     <chapter><title>Table Management</title>
1402     <para>
1403     Thuban distinguishes two different types of tables: Attribute tables
1404     (which belong to a layer) and normal data tables. Both provide
1405     the same general functionality with the difference that actions on an
1406     attribute table might also effect the map display.
1407     </para>
1408    
1409     <section><title>Table View</title>
1410     <para>
1411     <figure>
1412     <title>Table View</title>
1413     <mediaobject>
1414     <imageobject><imagedata fileref="../images/7_1_table_view.png" format="PNG" scale="&imgscale;"/></imageobject>
1415     <imageobject><imagedata fileref="./images/7_1_table_view.eps" format="EPS" scale="&imgscale;"/></imageobject>
1416     </mediaobject>
1417     </figure>
1418     </para>
1419     <para>
1420     Thuban provides a standard dialog to display table contents, the
1421     Table View. The view has five sections: The title, selections,
1422     the table grid, export functions, and the status bar.
1423     </para>
1424     <para>
1425     The title bar identifies the table with its name.
1426     </para>
1427     <para>
1428     The selections box let the user perform simple analysis on the data
1429     based on comparisons: The first choice must be a field identifier of
1430     the table, the second choice determines the type of comparison. The
1431     third choice can be either a specific value (interpreted as numerical
1432     or string depending on the type of the first field) or a second field
1433     identifier. Thus you can perform analysis like selecting all
1434     records where <literal>population > 10000</literal> or
1435     <literal>cars_per_inhabitant < bikes_per_inhabitant</literal>
1436     (note that the field names are only explanatory, the dBase files
1437     allow only 11 character field names).
1438    
1439     Selections can be combined either by applying a selection only on
1440     a previously selected set of records or by adding the results of a
1441     selection to a previous set. The default is that a selection replaces
1442     earlier results.
1443     </para>
1444     <para>
1445     The table grid shows the contents of the table (one record per row),
1446     with highlighted selection results. Columns and rows can be resized.
1447     </para>
1448     <para>
1449     The contents of a table can be exported into a file, either dBase
1450     format (DBF) or comma separated values (CSV). The
1451     <guibutton>Export</guibutton> button
1452     raises a file dialog to specify a path and file name, the export type
1453     is determined by the file extension (either .dbf or .csv).
1454    
1455     The <guibutton>Export Selection</guibutton> button works similarly
1456     but exports only the selected records.
1457    
1458     The <guibutton>Close</guibutton> button closes the table view window.
1459     This is different from the menu item
1460     <menuchoice>
1461     <guimenu>Table</guimenu>
1462     <guimenuitem>Close</guimenuitem>
1463     </menuchoice> which unloads the table from Thuban.
1464     </para>
1465     <para>
1466     The status bar displays some statistics about the table and optional
1467     selection results.
1468     </para>
1469     </section>
1470    
1471     <section><title>General Functionality (Menu Table)</title>
1472     <para>
1473     The general functions affect all tables open in Thuban. Attribute
1474     tables are considered here as normal data tables (with the exception
1475     that they cannot be closed).
1476     </para>
1477     <section><title>Open</title>
1478     <para>
1479     The
1480     <menuchoice>
1481     <guimenu>Table</guimenu>
1482     <guimenuitem>Open</guimenuitem>
1483     </menuchoice>
1484     item raises a file dialog to let you select a
1485     dBase file from the file system to be loaded into Thuban read-only.
1486     On <guibutton>OK</guibutton> the selected file is loaded and a
1487     table view is opened.
1488     </para>
1489     </section>
1490    
1491     <section><title>Close</title>
1492     <para>
1493     The
1494     <menuchoice>
1495     <guimenu>Table</guimenu>
1496     <guimenuitem>Close</guimenuitem>
1497     </menuchoice>
1498     item raises a dialog listing the currently open
1499     data tables
1500     (loaded via
1501     <menuchoice>
1502     <guimenu>Table</guimenu>
1503     <guimenuitem>Open</guimenuitem>
1504     </menuchoice>). Selected tables are dereferenced on confirmation.
1505     Since tables are opened read-only the contents of the tables are
1506     not affected.
1507    
1508     Any open views of the tables are closed as well.
1509    
1510     Tables used in a join cannot be closed.
1511     </para>
1512     </section>
1513    
1514     <section><title>Rename</title>
1515     <para>
1516     <menuchoice>
1517     <guimenu>Table</guimenu>
1518     <guimenuitem>Rename</guimenuitem>
1519     </menuchoice> changes the table title.
1520     </para>
1521     </section>
1522    
1523     <section><title>Show</title>
1524     <para>
1525     The
1526     <menuchoice>
1527     <guimenu>Table</guimenu>
1528     <guimenuitem>Show</guimenuitem>
1529     </menuchoice>
1530     item raises a list of available tables (explicitly
1531     loaded, attribute tables, results of a join). Selected tables are
1532     show in tables views on <guibutton>OK</guibutton>.
1533     </para>
1534     </section>
1535    
1536     <section><title>Join</title>
1537     <para>
1538     <figure>
1539     <title>Join Tables</title>
1540     <mediaobject>
1541     <imageobject><imagedata fileref="../images/7_2_5_join.png" format="PNG" scale="&imgscale;"/></imageobject>
1542     <imageobject><imagedata fileref="./images/7_2_5_join.eps" format="EPS" scale="&imgscale;"/></imageobject>
1543     </mediaobject>
1544     </figure>
1545     </para>
1546     <para>
1547     The
1548     <menuchoice>
1549     <guimenu>Table</guimenu>
1550     <guimenuitem>Join</guimenuitem>
1551     </menuchoice>
1552     item raises a dialog to specify the two tables to be
1553     joined. The join results in a new table named 'Join of "left table"
1554     and "right table"'.
1555    
1556     The dialog lets you select the two tables to be joined and the two
1557     fields the join has to be performed on. By default, the new
1558     table contains only those records which are matched by the join.
1559    
1560     If you want to preserve the records of the left table you can
1561     perform an outer join. The fields from the right table for records
1562     not matched by the join are filled with <varname>None</varname> in
1563     this case.
1564     </para>
1565     </section>
1566    
1567     </section>
1568     <section><title>Attribute Tables</title>
1569     <para>
1570     To clearly separate between both types of tables (data and
1571     attribute), Thuban provides functionality regarding the attribute
1572     tables under the <menuchoice><guimenu>Layer</guimenu></menuchoice> menu.
1573     </para>
1574    
1575     <section><title>Show Table</title>
1576     <para>
1577     <menuchoice>
1578     <guimenu>Layer</guimenu>
1579     <guimenuitem>Show Table</guimenuitem>
1580     </menuchoice>
1581     opens the attribute table of the currently active layer in a table
1582     view.
1583    
1584     In addition to the functionality described above selections
1585     affect also the map display: objects related to selected records
1586     are highlighted.
1587     </para>
1588     </section>
1589    
1590     <section><title>Join Table</title>
1591     <para>
1592     Unlike the join described above, the join does not result in a
1593     new table. The attribute table of the currently active layer is the
1594     left table and other tables are joined to this table. The results of
1595     the join are available for classification.
1596    
1597     As a consequence, the join cannot result in fewer
1598     records than the source attribute table. The user is warned if the
1599     right table does not fulfill this constraint. An outer join must be
1600     used in such cases.
1601     </para>
1602     </section>
1603    
1604     <section><title>Unjoin Table</title>
1605     <para>
1606     As said above, a normal table cannot be closed while it is still
1607     used in a join. While the joined table resulting from a join of
1608     normal tables can be simply closed (and thereby dereferencing
1609     the source tables), this is not possible for attribute tables.
1610    
1611     Hence joins on attribute tables must be solved explicitly. This is
1612     what the
1613     <menuchoice>
1614     <guimenu>Layer</guimenu>
1615     <guimenuitem>Unjoin Table</guimenuitem>
1616     </menuchoice>
1617     item is used for: The last join for the currently
1618     active layer is solved.
1619     </para>
1620     </section>
1621     </section>
1622     </chapter>
1623    
1624     <chapter><title>Extensions</title>
1625     <para>
1626     Thuban is designed to be extensible. The term Extension is used as a
1627     general term for anything that extends Thuban.
1628     This chapter introduces into some oppportunities how to add and
1629     handle extra functionality developed by your own or third parties.
1630     </para>
1631    
1632     <section><title>Add personal extensions via thubanstart.py</title>
1633     <para>
1634     After Thuban has been started for the first time, a directory
1635     .thuban is created within your home directory.
1636     There you can add a file thubanstart.py which will be imported
1637     by Thuban at start-up. It is recommended to add only import-statements
1638     to this file to keep the actual code of extensions separate.
1639     </para>
1640     <para>
1641     The modules to import must either be found through the environment
1642     variable PYTHONPATH or directly be placed into the .thuban-directory.
1643     </para>
1644     <para>
1645     As an example, copy the file examples/simple_extensions/hello_world.py
1646     of the Thuban source code into the .thuban-directory of your home
1647     directory. Now add add the statement import hello_world to the
1648     file thubanstart.py and run Thuban. You will notice an additional
1649     menu <menuchoice><guimenu>Extensions</guimenu></menuchoice> where
1650     the new item for the Hello-World extension is placed - select it
1651     to see the Hello-World message.
1652     </para>
1653     </section>
1654    
1655     <section><title>Extensions included in Thuban package</title>
1656     <para>
1657     The extensions described in this section are part of the
1658     Thuban package, but not activated by default.
1659     You will find them in the Thuban installation directory
1660     under <literal>Extensions/</literal>. Activate them as personal
1661     extensions via PYTHONPATH as described in the previous section.
1662     Stable extensions will appear under the menu
1663     <menuchoice><guimenu>Extensions</guimenu></menuchoice> and
1664     extensions which are in experimental state and therefore
1665     not fully functional under
1666     <menuchoice><guimenu>Experimental</guimenu></menuchoice>.
1667     </para>
1668    
1669     <section><title>Stable extensions</title>
1670     <para>
1671     These extensions provide extra-functionality to Thuban
1672     that has not (yet) been integrated in the main application.
1673     They are considered to be free of bugs, but may be
1674     further polished with helpful user interactions.
1675     </para>
1676     <section><title>gns2shp</title>
1677     <para>
1678     This tool converts data of the Geospatial Names Server
1679     (GNS, see <ulink url="http://www.nima.mil/gns"/>)
1680     into Shapefile format.
1681     The above web-site offer to download named places
1682     information grouped by countries for all of the world
1683     except USA for which other data are provided.
1684     </para>
1685     <para>
1686     If you download and unpack a package, you will have
1687     a text-file with suffix .txt.
1688     Selecting such a file via gns2shp will create the
1689     corresponding Shapefile with the same basename and
1690     place it in the same direcory. Afterwards it
1691     is automatically loaded into Thuban.
1692     The Shapefile will not automatically be delete afterwards.
1693     </para>
1694     <para>
1695     The gns2shp.py module can also be executed on the
1696     command line for batch processing purposes.
1697     </para>
1698     <para>
1699     A sample (<literal>ls.txt</literal> for Liechtenstein)
1700     is included in the directory
1701     <literal>Extensions/gns2shp/test</literal>.
1702     </para>
1703     </section>
1704     </section>
1705     <section><title>Experimental extensions</title>
1706     <para>
1707     All all of these functions have to be handled with care,
1708     since they are neither complete nor well tested.
1709     They are to be seen as a proof-of-concept and may
1710     additionally in some cases of practical help.
1711     </para>
1712     <para>
1713     Any interest on further improvement of these extensions
1714     should be communicated towards the developer and user
1715     community.
1716     </para>
1717    
1718     <section><title>importAPR</title>
1719     <para>
1720     This command offer to load an ESRI® ArcView® project
1721     file (suffix .apr) and convert it for use within Thuban.
1722     After selecting a apr-file to load, a list
1723     will be presented that offers to select one of the views
1724     of the apr-file, provided there is more than one.
1725     Furthermore, the Session Info-Tree is extended with
1726     a complete representation of the parsed apr-file.
1727     </para>
1728     <para>
1729     The legend of Thuban does not yet cover all of the elements as
1730     supported by the legend of ArcView®. Therefore, the Thuban
1731     map will look different. Furthermore, the apr-format is
1732     a proprietary format, not openly documented.
1733     Therefore, the interpretation is
1734     partly based on reverse engeneering and good guessing.
1735     </para>
1736     <para>
1737     The file-paths within the apr-file may not fit and potentially
1738     are subject to fix in the apr-file. You can do this
1739     applying any text editor. The paths are either absolute
1740     or relative from where Thuban has been started.
1741     </para>
1742     <para>
1743     A sample for the Iceland data is included as
1744     <literal>Extensions/importAPR/samples/iceland.apr</literal>.
1745     The file-paths are relative from the Thuban main directory.
1746     </para>
1747     </section>
1748     </section>
1749     </section>
1750    
1751     <section><title>Writing simple extensions</title>
1752     <para>
1753     Writing an extension for Thuban basically means to
1754     implement the extra functionality in Python with all of the
1755     Thuban classes, methods and variables available.
1756     </para>
1757     <para>
1758     All classes and their methods are documented in the source code
1759     (see their doc-strings). Here is an example from
1760     Thuban/Model/layer.py that describes some of the methods
1761     of a Layer object:
1762     </para>
1763     <programlisting>
1764     <![CDATA[
1765     class BaseLayer(TitledObject, Modifiable):
1766    
1767     """Base class for the layers."""
1768    
1769     def __init__(self, title, visible = True, projection = None):
1770     """Initialize the layer.
1771    
1772     title -- the title
1773     visible -- boolean. If true the layer is visible.
1774     """
1775     TitledObject.__init__(self, title)
1776     Modifiable.__init__(self)
1777     self.visible = visible
1778     self.projection = projection
1779    
1780     def Visible(self):
1781     """Return true if layer is visible"""
1782     return self.visible
1783    
1784     def SetVisible(self, visible):
1785     """Set the layer's visibility."""
1786     self.visible = visible
1787     self.issue(LAYER_VISIBILITY_CHANGED, self)
1788    
1789     def HasClassification(self):
1790     """Determine if this layer support classifications."""
1791     ...
1792     ]]>
1793     </programlisting>
1794     <para>
1795     This example intends to give you an impression of the
1796     source-code-level documentation.
1797     You have to make yourself familiar with
1798     the Python programming language to understand some special
1799     code elements.
1800     </para>
1801     <section><title>hello_world.py</title>
1802     <para>
1803     Traditionally, the first example should welcome the world.
1804     Most of the code handles the frame for integrating a menu
1805     item into Thuban while the actual raising of a message
1806     is done in a single line.
1807     </para>
1808     <programlisting>
1809     <![CDATA[
1810     # Copyright (C) 2003 by Intevation GmbH
1811     # Authors:
1812     # Jan-Oliver Wagner <[email protected]>
1813     #
1814     # This program is free software under the GPL (>=v2)
1815     # Read the file COPYING coming with Thuban for details.
1816    
1817     """
1818     Extend Thuban with a sample Hello World to demonstrate simple
1819     extensions.
1820     """
1821    
1822     __version__ = '$Revision$'
1823    
1824     # use _() already now for all strings that may later be translated
1825     from Thuban import _
1826    
1827     # Thuban has named commands which can be registered in the central
1828     # instance registry.
1829     from Thuban.UI.command import registry, Command
1830    
1831     # The instance of the main menu of the Thuban application
1832     # See Thuban/UI/menu.py for the API of the Menu class
1833     from Thuban.UI.mainwindow import main_menu
1834    
1835     def hello_world_dialog(context):
1836     """Just raise a simple dialog to greet the world.
1837    
1838     context -- The Thuban context.
1839     """
1840     context.mainwindow.RunMessageBox(_('Hello World'), _('Hello World!'))
1841    
1842    
1843     # create a new command and register it
1844     registry.Add(Command('hello_world', _('Hello World'), hello_world_dialog,
1845     helptext = _('Welcome everyone on this planet')))
1846    
1847     # find the extensions menu (create it anew if not found)
1848     extensions_menu = main_menu.FindOrInsertMenu('extensions', _('E&xtensions'))
1849    
1850     # finally bind the new command with an entry in the extensions menu
1851     extensions_menu.InsertItem('hello_world')
1852     ]]>
1853     </programlisting>
1854     </section>
1855     <section><title>Registering a Command</title>
1856     <para>
1857     Mainly, our new function has to be registered to the Thuban
1858     framework in order to connect it to the menu. A registered
1859     command can also be connected to e.g. a toolbar button.
1860     </para>
1861     <para>
1862     The instances and classes for this are imported at the beginning.
1863     Any code not inside a method or class is directly executed when
1864     the source-code module is imported. Therefore, the second
1865     part of this example consist of the plain statements to create a new
1866     Command and to add it to the menu.
1867     </para>
1868     <para>
1869     By convention, it looks for a menu registered as ``extensions'' to
1870     insert the new command. If it does not exist yet, it gets created.
1871     It is advisable to copy this code for any of your extensions.
1872     </para>
1873     </section>
1874     <section><title>The Thuban context</title>
1875     <para>
1876     A registered command that is called, always receives the
1877     Thuban context. This instance provides our method with
1878     hook references to all important components of the Thuban
1879     application.
1880     </para>
1881     <para>
1882     In the example hello_world.py, our function uses the
1883     mainwindow component which offers a method to raise a
1884     message dialog. In total there are three hooks:
1885     <itemizedlist>
1886     <listitem>
1887     <para>application:
1888     This object is the instance of the Thuban Application class.
1889     Except maybe for loading or savinf sessions, you will not
1890     need this object for a simple extension.
1891     See Thuban/UI/application.py for the API.
1892     </para>
1893     </listitem>
1894     <listitem>
1895     <para>session:
1896     The instance of the current session. It manages the sessions'
1897     map and tables. You can set and remove the map or tables.
1898     In may also get the map object. However, you should know that
1899     internally it is already prepared to handle many maps.
1900     Therfore, currently you would always receive a list with exactlty
1901     one element. In the future, if there are more than one map,
1902     you will not know which one is the currently display one and
1903     therefore you should use the mainwindow as hook to find
1904     the currently displayed map.
1905     See Thuban/Model/session.py for the API.
1906     </para>
1907     </listitem>
1908     <listitem>
1909     <para>
1910     mainwindow: The mainwindow object is central to manage various
1911     GUI things such as the Legend sub-window. Most notably,
1912     you get access to the canvas which is the window part where
1913     the map is drawn. The canvas knows, which map it currently
1914     draws and therefore you get the current map via
1915     context.mainwindow.canvas.Map().
1916     See Thuban/UI/mainwindow.py for the API.
1917     </para>
1918     </listitem>
1919     </itemizedlist>
1920     </para>
1921     </section>
1922     </section>
1923     </chapter>
1924    
1925     <chapter><title>Trouble Shooting</title>
1926     <para>
1927     Here are a few problems that users have encountered when first using Thuban.
1928     </para>
1929     <para>
1930    
1931     <itemizedlist>
1932     <listitem>
1933     <para>After adding two or more layers nothing is drawn in the map window.
1934     </para>
1935     <para>
1936     This is probably because the layers have different projections. Projections
1937     must be set on all layers and on the map itself if the layers' projections
1938     are different.
1939     </para>
1940     </listitem>
1941    
1942     <listitem>
1943     <para>Thuban crashes on startup with the error
1944     <literal>NameError: global name 'False' is not defined</literal>.
1945     </para>
1946     <para>
1947     <varname>True</varname> and <varname>False</varname> were only introduced
1948     in Python 2.2.1. Thuban depends on at least Python 2.2.1.
1949     </para>
1950     </listitem>
1951    
1952     <listitem>
1953     <para>After compiling Thuban, Thuban crashes with an error similar to
1954     <literal>
1955     ImportError: /usr/local//lib/thuban/Thuban/../Lib/wxproj.so: undefined symbol: __gxx_personality_v0
1956     </literal>
1957     </para>
1958     <para>
1959     Thuban depends on the wxWindows library. If Thuban is compiled with an
1960     incompatible version of the compiler than wxWindows was compiled with
1961     this error may occur. Try compiling with a different version of the
1962     compiler.
1963     </para>
1964     </listitem>
1965     </itemizedlist>
1966     </para>
1967     <para>
1968     If an error occurs Thuban will display a dialog indicating the error
1969     before closing. The text should be copied and reported to the
1970     <ulink url="http://thuban.intevation.org/bugtracker.html">
1971     Intevation bugtracker
1972     </ulink>.
1973     More information about the system is available from
1974     <menuchoice><guimenu>Help</guimenu><guimenuitem>About</guimenuitem></menuchoice> box.
1975     This should also be included in the bug report.
1976     <figure>
1977     <title>Error Dialog</title>
1978     <mediaobject>
1979     <imageobject><imagedata fileref="../images/8_int_error.png" format="PNG" scale="&imgscale;"/></imageobject>
1980     <imageobject><imagedata fileref="./images/8_int_error.eps" format="EPS" scale="&imgscale;"/></imageobject>
1981     </mediaobject>
1982     </figure>
1983     </para>
1984    
1985     </chapter>
1986    
1987     <appendix><title>Supported Data Sources</title>
1988     <para>
1989     </para>
1990     <variablelist>
1991     <varlistentry>
1992     <term>Shapefile</term>
1993     <listitem>
1994     <para>
1995     The Shapefile format has become a standard format for saving
1996     geographic vector information. It supports polygons, lines, and
1997     points.
1998    
1999     <ulink url="http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf">
2000     Technical Specification.
2001     </ulink>
2002     </para>
2003     </listitem>
2004     </varlistentry>
2005    
2006     <varlistentry>
2007     <term>dBase file</term>
2008     <listitem>
2009     <para>
2010     dBase files are used to store the attributes for each layer. This
2011     is closely associated with the Shapefile format. For detailed
2012     specifications on the correct format of a dBase file used with
2013     Thuban please see the Technical Specification for the Shapefile
2014     format above.
2015     </para>
2016     </listitem>
2017     </varlistentry>
2018    
2019     <varlistentry>
2020     <term>PostGIS</term>
2021     <listitem>
2022     <para>
2023     PostGIS adds support for geographic objects to the PostgreSQL
2024     object-relational database. Different layer types (as for Shapefiles)
2025     are supported. <ulink url="http://postgis.refractions.net">PostGIS
2026     Homepage</ulink>
2027     </para>
2028     </listitem>
2029     </varlistentry>
2030    
2031     <varlistentry>
2032     <term>Raster files</term>
2033     <listitem>
2034     <para>
2035     Binding the GDAL library Thuban supports numerous raster file formats,
2036     see <ulink url="http://www.remotesensing.org/gdal/formats_list.html">
2037     GDAL format list</ulink> for details.</para>
2038    
2039     <para>Most commonly used is the <emphasis>TIFF/GeoTIFF</emphasis>
2040     format: Raster maps are provided as TIFF images, with an additional
2041     "world file" storing the geographic reference (usually with an
2042     extension ".tfw").
2043     </para>
2044     </listitem>
2045     </varlistentry>
2046    
2047     </variablelist>
2048     </appendix>
2049    
2050     <appendix><title>Working with PostGIS</title>
2051     <para>
2052     This section focusses on the use of PostGIS in the Thuban framework. For
2053     installation and maintenance of spatial databases we refer to the
2054     <ulink url="http://postgis.refractions.net">PostGIS Homepage</ulink>.
2055     The Thuban PostGIS support requires the
2056     <ulink url="http://initd.org/software/psycopg">psycopg module</ulink>.
2057     </para>
2058    
2059     <para>
2060     Working with PostGIS Databases is seperated into two steps:
2061     <itemizedlist>
2062     <listitem><para>Opening a Database Connection</para></listitem>
2063     <listitem><para>Loading a Data Layer</para></listitem>
2064     </itemizedlist>
2065     </para>
2066     <section><title>Opening a Database Connection</title>
2067     <para>
2068     Before a data layer can be loaded from a PostGIS database a
2069     connection with the database has to be established.
2070     <menuchoice>
2071     <guimenu>Session</guimenu>
2072     <guimenuitem>Database Connections ...</guimenuitem>
2073     </menuchoice> opens a dialog for database connection
2074     management. In the dialog new connections can be added
2075     and existing ones can be removed. Removing a database
2076     connection is not possible if the map still displays a
2077     layer provided by this database connection.
2078     </para>
2079     <figure>
2080     <title>Database Management Dialog</title>
2081     <mediaobject>
2082     <imageobject><imagedata fileref="../images/app_postgis_db_management.png" format="PNG" scale="&imgscale;"/></imageobject>
2083     <imageobject><imagedata fileref="./images/app_postgis_db_management.eps" format="EPS" scale="&imgscale;"/></imageobject>
2084     </mediaobject>
2085     </figure>
2086    
2087     <para>
2088     To add a new database connection to the session a dialog is
2089     opened to specify the relevant connection data. Enter all
2090     data relevant for your connection. If the connection fails
2091     the dialog remains open and provides some hints on the failure.
2092     </para>
2093     <figure>
2094     <title>Add Database Dialog</title>
2095     <mediaobject>
2096     <imageobject><imagedata fileref="../images/app_postgis_db_add.png" format="PNG" scale="&imgscale;"/></imageobject>
2097     <imageobject><imagedata fileref="./images/app_postgis_db_add.eps" format="EPS" scale="&imgscale;"/></imageobject>
2098     </mediaobject>
2099     </figure>
2100    
2101     <para>
2102     It is important to note that information on database connections are
2103     also stored with the session. Passwords are NOT stored. If you load a
2104     session with database connections you are asked to enter these
2105     passwords again where required.
2106     </para>
2107    
2108     </section>
2109    
2110     <section><title>Loading a Data Layer</title>
2111     <para>
2112     Data layers as part of a map are loaded with the
2113     <menuchoice>
2114     <guimenu>Map</guimenu>
2115     <guimenuitem>Add Database Layer ...</guimenuitem>
2116     </menuchoice> menu item. A dialog is raised displaying two choice
2117     lists. In the left list all connected databases are shown.
2118     Highlighting
2119     one of these and issuing a retrieval results in a list of available
2120     layer tables from that database. After selection of a
2121     layer the dialog is closed.
2122     </para>
2123     <figure>
2124     <title>Add Database Dialog</title>
2125     <mediaobject>
2126     <imageobject><imagedata fileref="../images/app_postgis_add_layer.png" format="PNG" scale="&imgscale;"/></imageobject>
2127     <imageobject><imagedata fileref="./images/app_postgis_add_layer.eps" format="EPS" scale="&imgscale;"/></imageobject>
2128     </mediaobject>
2129     </figure>
2130    
2131     </section>
2132    
2133     </appendix>
2134    
2135     <appendix><title>Supported Projections</title>
2136     <para>
2137     The following types of projections are directly support by
2138     Thuban. The specific values for each are provided by the user
2139     to create custom projections. Thuban comes with predefined
2140     projections which are available through the Projections dialog.
2141     </para>
2142     <itemizedlist>
2143     <listitem>
2144     <para>Geographic</para>
2145     <itemizedlist>
2146     <listitem><para><literal>Ellipsoid</literal></para></listitem>
2147     <listitem><para>
2148     <literal>Source Data</literal>: either Degrees or Radians
2149     </para></listitem>
2150     </itemizedlist>
2151     </listitem>
2152     <listitem>
2153     <para>Lambert Conic Conformal</para>
2154     <itemizedlist>
2155     <listitem><para><literal>Ellipsoid</literal></para></listitem>
2156     <listitem><para><literal>Latitude of 1st standard parallel</literal></para></listitem>
2157     <listitem><para><literal>Latitude of 2nd standard parallel</literal></para></listitem>
2158     <listitem><para><literal>Central Meridian</literal></para></listitem>
2159     <listitem><para><literal>Latitude of Origin</literal></para></listitem>
2160     <listitem><para><literal>False Easting</literal> (meters)</para></listitem>
2161     <listitem><para><literal>False Northing</literal> (meters)</para></listitem>
2162     </itemizedlist>
2163     </listitem>
2164     <listitem>
2165     <para>Transverse Mercator</para>
2166     <itemizedlist>
2167     <listitem><para><literal>Ellipsoid</literal></para></listitem>
2168     <listitem><para><literal>Latitude</literal>of origin</para></listitem>
2169     <listitem><para><literal>Longitude</literal>at central meridian</para></listitem>
2170     <listitem><para><literal>Scale Factor</literal>at central meridian</para></listitem>
2171     <listitem><para><literal>False Easting</literal> (meters)</para></listitem>
2172     <listitem><para><literal>False Northing</literal> (meters)</para></listitem>
2173     </itemizedlist>
2174     </listitem>
2175     <listitem>
2176     <para>Universal Transverse Mercator</para>
2177     <itemizedlist>
2178     <listitem><para><literal>Ellipsoid</literal></para></listitem>
2179     <listitem><para><literal>Zone</literal>
2180     (can be guessed appling the Propose button)</para></listitem>
2181     <listitem><para><literal>Southern Hemisphere</literal> flag</para></listitem>
2182     </itemizedlist>
2183     </listitem>
2184     </itemizedlist>
2185    
2186     <para>
2187     Thuban comes with a sample set of map projections for various
2188     European countries. Apart from the basic projection they differ
2189     especially in their parameterization:
2190     </para>
2191     <itemizedlist>
2192     <listitem><para>Belgium Datum 1972 (Lambert Conic Conformal)</para>
2193     </listitem>
2194    
2195     <listitem><para>Gauss-Boaga Zone 1 (Italy, Transverse Mercartor)</para>
2196     </listitem>
2197    
2198     <listitem><para>Gauss-Krueger Zone 2 (Germany, Transverse Mercartor)
2199     </para>
2200     </listitem>
2201    
2202     <listitem><para>Reseau Geodesique Francaise
2203     (France, Lambert Conic Conformal)</para>
2204     </listitem>
2205    
2206     <listitem><para>UK National Grid (United Kingdom, Transverse Mercartor)
2207     </para>
2208     </listitem>
2209     </itemizedlist>
2210    
2211     <para>
2212     Thuban uses the comprehensive PROJ library for projections. PROJ provides
2213     more than the four commonly used projections described above. If needed
2214     Thuban can be easily extended to a new projection covered by PROJ.
2215     </para>
2216     </appendix>
2217    
2218     </book>
2219    

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