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German Users Manual

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     <menuchoice>
436     <guimenu>Karte</guimenu>
437     <guimenuitem>Legende</guimenuitem>
438     </menuchoice>.
439     The legend is also dockable, which means that it can be detached
440     from the main window by clicking on the small button next to the
441     close button. It can be attached by clicking the same button
442     again.
443     </para>
444     <para>
445     The status bar displays different information depending on the
446     current context. If the user is selecting an item from the menu
447     then the status bar will display a short help message indicating
448     what each menu item is for. If the user has a tool selected then
449     the position of the cursor on the map is displayed.
450     </para>
451     <para>
452     The tool bar provides quick access to the commonly needed tools.
453     By hovering over each button the user can see a short messages
454     describing what the tool does. The tools provided are Zoom In, Zoom
455     Out, Pan, Full Extent, Full Layer Extent, Full Shape Extent, Identify,
456     and Label. Each of the tools will be explained in further detail later
457     in the manual.
458     </para>
459     </section>
460    
461     </chapter>
462    
463     <chapter><title>Session Management</title>
464    
465     <section><title>Starting a New Session</title>
466     <para>
467     A new session can be started from
468     <menuchoice>
469     <guimenu>File</guimenu>
470     <guimenuitem>New Session</guimenuitem>
471     </menuchoice>.
472     If a session is already loaded and has been modified without
473     being saved a prompt will ask if the current session should
474     be saved. A new session consists of an empty map with no
475     layers and no tables.
476     </para>
477     </section>
478    
479     <section><title>Opening a Session</title>
480     <para>
481     A session can be opened from
482     <menuchoice>
483     <guimenu>File</guimenu>
484     <guimenuitem>Open Session</guimenuitem>
485     </menuchoice>. A dialog box will open allowing the user to browse
486     for a Thuban Session file. Thuban session files end with
487     <varname>.thuban</varname>. Selecting a file a clicking
488     <guibutton>OK</guibutton> will load the session into Thuban.
489    
490     If a session is already loaded and has been modified without
491     being saved a prompt will ask if the current session should
492     be saved.
493     </para>
494     </section>
495    
496     <section><title>Saving a Session</title>
497     <para>
498     A session can be saved from
499     <menuchoice>
500     <guimenu>File</guimenu>
501     <guimenuitem>Save Session</guimenuitem>
502     </menuchoice>. A dialog box will open allowing the user to browse
503     the file system and select a place to save the session. Thuban
504     sessions should be saved under a name ending in
505     <varname>.thuban</varname>. If the file already exists the user
506     will be prompted to save under a different name or overwrite the
507     existing file.
508     </para>
509     </section>
510    
511     <section><title>The Session Info-Tree</title>
512     <para>
513     <figure>
514     <title>Session Info Tree</title>
515     <mediaobject>
516     <imageobject><imagedata fileref="../images/2_4_session_tree.png" format="PNG" scale="&imgscale;"/></imageobject>
517     <imageobject><imagedata fileref="./images/2_4_session_tree.eps" format="EPS" scale="&imgscale;"/></imageobject>
518     </mediaobject>
519     </figure>
520     </para>
521     <para>
522     The session info-tree is primarily intended for developers working
523     with Thuban. It displays many of the internal values for the session,
524     map, and layers. It can be opened from
525     <menuchoice>
526     <guimenu>File</guimenu>
527     <guimenuitem>Session Tree</guimenuitem>
528     </menuchoice>.
529     </para>
530     </section>
531     </chapter>
532    
533     <chapter><title>Map Management</title>
534     <para>
535     The map consists of a number of layers where each layer represents a
536     different type of data set. By interacting with the map the user can
537     visually explore the data.
538     </para>
539     <para>
540     The map can have a name that will appear in the Thuban title bar.
541     The map name can be changed using
542     <menuchoice>
543     <guimenu>Map</guimenu>
544     <guimenuitem>Rename</guimenuitem>
545     </menuchoice>.
546     </para>
547     <para>
548     <inlinemediaobject>
549     <imageobject>
550     <imagedata fileref="../images/3_rename_map.png" format="PNG" scale="&imgscale;"/>
551     </imageobject>
552     <imageobject>
553     <imagedata fileref="./images/3_rename_map.eps" format="EPS" scale="&imgscale;"/>
554     </imageobject>
555     <textobject> <phrase>Rename Map</phrase> </textobject>
556     </inlinemediaobject>
557     </para>
558    
559     <section><title>Adding and Removing Layers</title>
560     <para>
561     There are three types of layers that can be added to a map:
562     Shape layers, database layers
563     and image layers. Shape layers are stored in Shapefile format, a
564     widely used file format for storing geographic objects. These
565     files have the extension ``.shp''. Associated with
566     the shape file is a database file which stores attributes for
567     each shape in the Shape file. This file, in dBase format,
568     has the extension ``.dbf''. Both files must have the same base name.
569     For example, if there is a shape file named roads.shp there must
570     also be a file roads.dbf.
571     </para>
572     <itemizedlist>
573     <listitem>
574     <para>
575     Shape layers can be added to the map with
576     <menuchoice>
577     <guimenu>Map</guimenu>
578     <guimenuitem>Add Layer</guimenuitem>
579     </menuchoice>.
580     Initially, only the ``.shp'' files are shown which is enough for the
581     selection. However, if you switch to display all files and select one
582     of the associated files (e.g. ``.dbf''), Thuban will recognize the base
583     name and load the corresponding Shape file.
584     </para>
585     <para>
586     The file dialog for Shape files allows to select multiple files.
587     Use the shift-button together with the left mouse button to extend
588     the selection.
589     </para>
590     </listitem>
591    
592     <listitem>
593     <para>Database layers can be added to the map with
594     <menuchoice>
595     <guimenu>Map</guimenu>
596     <guimenuitem>Add Database Layer</guimenuitem>
597     </menuchoice>.
598     A dialog with two is list is opened. The left list displays all
599     database connections currently open for the session. You can retrieve
600     a list of available layers from the selected database which is
601     displayed on the right hand. From this list one layer can be selected,
602     the dialog is closed afterwards.
603     </para>
604     <para>
605     See appendix ``Working with PostGIS'' for details.
606     </para>
607     </listitem>
608    
609     <listitem>
610     <para>
611     Image layers can be added to the map with
612     <menuchoice>
613     <guimenu>Map</guimenu>
614     <guimenuitem>Add Image Layer</guimenuitem>
615     </menuchoice>.
616     It is important to select a valid image file that has geographic
617     data associated with it. The data can be embedded in the file itself,
618     or in another file. If geographic information cannot be found, Thuban
619     will report an error.
620     </para>
621     </listitem>
622     </itemizedlist>
623     </section>
624    
625     <section><title>Navigation</title>
626     <para>
627     The map can be explored by using the navigation tools available on
628     the tool bar or from the
629     <menuchoice><guimenu>Map</guimenu></menuchoice> menu.
630     </para>
631     <itemizedlist>
632     <listitem>
633     <para>
634     The ZoomIn tool
635     <inlinemediaobject>
636     <imageobject>
637     <imagedata fileref="../images/3_2_zoomin.png" format="PNG" scale="&imgscale;"/>
638     </imageobject>
639     <imageobject>
640     <imagedata fileref="./images/3_2_zoomin.eps" format="EPS" scale="&imgscale;"/>
641     </imageobject>
642     <textobject> <phrase>ZoomIn Tool</phrase> </textobject>
643     </inlinemediaobject>
644     enlarges a region of the map. Clicking once on the map
645     will double the magnification and center the map on the point that
646     was clicked. Clicking and dragging selects a region that will be
647     enlarged to fit the window.
648     </para>
649     </listitem>
650     <listitem>
651     <para>
652     The ZoomOut tool
653     <inlinemediaobject>
654     <imageobject>
655     <imagedata fileref="../images/3_2_zoomout.png" format="PNG" scale="&imgscale;"/>
656     </imageobject>
657     <imageobject>
658     <imagedata fileref="./images/3_2_zoomout.eps" format="EPS" scale="&imgscale;"/>
659     </imageobject>
660     <textobject> <phrase>ZoomOut Tool</phrase> </textobject>
661     </inlinemediaobject>
662     shrinks the map so that a larger region is visible. A single click
663     reduces the magnification by a factor of two. Clicking and dragging
664     selects a box such that the current contents of the window will be
665     scaled to fit into that box.
666     </para>
667     </listitem>
668     <listitem>
669     <para>
670     The Pan tool
671     <inlinemediaobject>
672     <imageobject>
673     <imagedata fileref="../images/3_2_pan.png" format="PNG" scale="&imgscale;"/>
674     </imageobject>
675     <imageobject>
676     <imagedata fileref="./images/3_2_pan.eps" format="EPS" scale="&imgscale;"/>
677     </imageobject>
678     <textobject> <phrase>Pan Tool</phrase> </textobject>
679     </inlinemediaobject>
680     allows the user to move the map around by clicking and dragging.
681     </para>
682     </listitem>
683     <listitem>
684     <para>
685     The Full Extent tool
686     <inlinemediaobject>
687     <imageobject>
688     <imagedata fileref="../images/3_2_fullextent.png" format="PNG" scale="&imgscale;"/>
689     </imageobject>
690     <imageobject>
691     <imagedata fileref="./images/3_2_fullextent.eps" format="EPS" scale="&imgscale;"/>
692     </imageobject>
693     <textobject> <phrase>Full Extent Tool</phrase> </textobject>
694     </inlinemediaobject>
695     rescales the viewable region so that the entire map is visible.
696     </para>
697     </listitem>
698     <listitem>
699     <para>
700     The Full Layer Extent tool
701     <inlinemediaobject>
702     <imageobject>
703     <imagedata fileref="../images/3_2_fulllayerextent.png" format="PNG" scale="&imgscale;"/>
704     </imageobject>
705     <imageobject>
706     <imagedata fileref="./images/3_2_fulllayerextent.eps" format="EPS" scale="&imgscale;"/>
707     </imageobject>
708     <textobject> <phrase>Full Layer Extent Tool</phrase> </textobject>
709     </inlinemediaobject>
710     rescales the viewable region so that the currently selected
711     layer fits within the window. If no layer is selected this button
712     will be disabled.
713     </para>
714     </listitem>
715     <listitem>
716     <para>
717     The Full Shape Extent tool
718     <inlinemediaobject>
719     <imageobject>
720     <imagedata fileref="../images/3_2_fullshapeextent.png" format="PNG" scale="&imgscale;"/>
721     </imageobject>
722     <imageobject>
723     <imagedata fileref="./images/3_2_fullshapeextent.eps" format="EPS" scale="&imgscale;"/>
724     </imageobject>
725     <textobject> <phrase>Full Shape Extent Tool</phrase> </textobject>
726     </inlinemediaobject>
727     rescales the viewable region so that the currently selected
728     shape fits within the window. If the shape is a point, it is
729     centered and the map is zoomed all the way in. If no shape is
730     selected this button will be disabled. This feature is especially
731     helpful when identifying an object related to a selected record
732     in a tableview (see below).
733    
734     </para>
735     </listitem>
736     </itemizedlist>
737     </section>
738    
739     <section><title>Object Identification</title>
740     <para>
741     Objects on the map can be identified using the Identify tool
742     <inlinemediaobject>
743     <imageobject>
744     <imagedata fileref="../images/3_3_identify.png" format="PNG" scale="&imgscale;"/>
745     </imageobject>
746     <imageobject>
747     <imagedata fileref="./images/3_3_identify.eps" format="EPS" scale="&imgscale;"/>
748     </imageobject>
749     <textobject> <phrase>Identify Tool</phrase> </textobject>
750     </inlinemediaobject>.
751     Clicking on an object selects that object and opens a dialog which
752     shows all the table attributes for that object. Any current selection
753     is lost. Objects on the map are typically shapes and this document
754     will often refer to objects as shapes.
755     </para>
756     </section>
757    
758     <section><title>Object Labeling</title>
759     <para>
760     Objects can be labeled using the Label tool
761     <inlinemediaobject>
762     <imageobject>
763     <imagedata fileref="../images/3_3_label.png" format="PNG" scale="&imgscale;"/>
764     </imageobject>
765     <imageobject>
766     <imagedata fileref="./images/3_3_label.eps" format="EPS" scale="&imgscale;"/>
767     </imageobject>
768     <textobject> <phrase>Label Tool</phrase> </textobject>
769     </inlinemediaobject>.
770     Clicking on an object selects that object and opens a dialog which
771     displays the table attributes for that object. An attribute can
772     be selected to be the label on the map. The label will be placed
773     at the center of the shape. Clicking on an object that already has
774     a label will remove the label.
775     </para>
776     </section>
777    
778     <section><title>The Legend</title>
779     <para>
780     <inlinemediaobject>
781     <imageobject>
782     <imagedata fileref="../images/3_5_legend.png" format="PNG" scale="&imgscale;"/>
783     </imageobject>
784     <imageobject>
785     <imagedata fileref="./images/3_5_legend.eps" format="EPS" scale="&imgscale;"/>
786     </imageobject>
787     <textobject> <phrase>Legend</phrase> </textobject>
788     </inlinemediaobject>
789     </para>
790     <para>
791     The Legend provides an overview of the layers in the map. Layers
792     that appear higher in the legend will appear ``closer'' to the user.
793     If a layer supports classification (currently, only shape layers
794     have this feature) then the classification groups will be shown
795     below each layer. The properties for each group are also displayed
796     with a small graphic. Polygon layers appear as rectangles, lines
797     appear as curved lines, and points appear as circles.
798     </para>
799     <para>
800     Along the top of the legend is a toolbar which allows quick access
801     to some of the layer manipulation options under
802     <menuchoice><guimenu>Map</guimenu></menuchoice>.
803     </para>
804    
805     <itemizedlist>
806     <listitem>
807     <para>
808     The Move Layer to Top tool
809     <inlinemediaobject>
810     <imageobject>
811     <imagedata fileref="../images/3_5_totop.png" format="PNG" scale="&imgscale;"/>
812     </imageobject>
813     <imageobject>
814     <imagedata fileref="./images/3_5_totop.eps" format="EPS" scale="&imgscale;"/>
815     </imageobject>
816     <textobject> <phrase>Move Layer to Top</phrase> </textobject>
817     </inlinemediaobject> raises the selected layer to the top of the map.
818     </para>
819     </listitem>
820     <listitem>
821    
822     <para>
823     The Move Layer Up tool
824     <inlinemediaobject>
825     <imageobject>
826     <imagedata fileref="../images/3_5_moveup.png" format="PNG" scale="&imgscale;"/>
827     </imageobject>
828     <imageobject>
829     <imagedata fileref="./images/3_5_moveup.eps" format="EPS" scale="&imgscale;"/>
830     </imageobject>
831     <textobject> <phrase>Move Layer Up</phrase> </textobject>
832     </inlinemediaobject> raises the selected layer one level.
833     </para>
834     </listitem>
835     <listitem>
836    
837     <para>
838     The Move Layer Down tool
839     <inlinemediaobject>
840     <imageobject>
841     <imagedata fileref="../images/3_5_movedown.png" format="PNG" scale="&imgscale;"/>
842     </imageobject>
843     <imageobject>
844     <imagedata fileref="./images/3_5_movedown.eps" format="EPS" scale="&imgscale;"/>
845     </imageobject>
846     <textobject> <phrase>Move Layer Down</phrase> </textobject>
847     </inlinemediaobject> lowers the selected layer one level.
848     </para>
849    
850     </listitem>
851     <listitem>
852     <para>
853     The Move Layer to Bottom tool
854     <inlinemediaobject>
855     <imageobject>
856     <imagedata fileref="../images/3_5_tobottom.png" format="PNG" scale="&imgscale;"/>
857     </imageobject>
858     <imageobject>
859     <imagedata fileref="./images/3_5_tobottom.eps" format="EPS" scale="&imgscale;"/>
860     </imageobject>
861     <textobject> <phrase>Move Layer to Bottom</phrase> </textobject>
862     </inlinemediaobject> lowers the selected layer to the bottom of the map.
863     </para>
864    
865     </listitem>
866     <listitem>
867     <para>
868     The Visible tool
869     <inlinemediaobject>
870     <imageobject>
871     <imagedata fileref="../images/3_5_visible.png" format="PNG" scale="&imgscale;"/>
872     </imageobject>
873     <imageobject>
874     <imagedata fileref="./images/3_5_visible.eps" format="EPS" scale="&imgscale;"/>
875     </imageobject>
876     <textobject> <phrase>Visible</phrase> </textobject>
877     </inlinemediaobject> shows the selected layer in the map if it was
878     hidden.
879     </para>
880    
881     </listitem>
882     <listitem>
883     <para>
884     The Invisible tool
885     <inlinemediaobject>
886     <imageobject>
887     <imagedata fileref="../images/3_5_invisible.png" format="PNG" scale="&imgscale;"/>
888     </imageobject>
889     <imageobject>
890     <imagedata fileref="./images/3_5_invisible.eps" format="EPS" scale="&imgscale;"/>
891     </imageobject>
892     <textobject> <phrase>Invisible</phrase> </textobject>
893     </inlinemediaobject> hides the selected layer in the map.
894     </para>
895    
896     </listitem>
897     <listitem>
898     <para>
899     The Properties tool
900     <inlinemediaobject>
901     <imageobject>
902     <imagedata fileref="../images/3_5_props.png" format="PNG" scale="&imgscale;"/>
903     </imageobject>
904     <imageobject>
905     <imagedata fileref="./images/3_5_props.eps" format="EPS" scale="&imgscale;"/>
906     </imageobject>
907     <textobject> <phrase>Properties</phrase> </textobject>
908     </inlinemediaobject> opens the layer's properties dialog box.
909     Double-clicking on a layer or a group of a layer will open the
910     properties dialog for that layer.
911     </para>
912     </listitem>
913     </itemizedlist>
914    
915     <para>
916     The most used layer related actions are also available from a
917     popup menu. It is raised when a layer is clicked with the right mouse
918     button.
919     </para>
920    
921     <para>
922     <figure>
923     <title>Layer Popup Menu</title>
924     <mediaobject>
925     <imageobject><imagedata fileref="../images/3_5_popup_menu.png" format="PNG" scale="&imgscale;"/></imageobject>
926     <imageobject><imagedata fileref="./images/3_5_popup_menu.eps" format="EPS" scale="&imgscale;"/></imageobject>
927     </mediaobject>
928     </figure>
929     </para>
930    
931     <para>
932     Along the bottom of the legend is the scalebar. The scalebar
933     will be available if there are any layers and the map has a
934     projection set.
935     </para>
936     </section>
937    
938     <section><title>Exporting</title>
939     <para>
940     Under Windows, maps can be exported in Enhanced Metafile format
941     (<varname>.wmf</varname>)
942     from
943     <menuchoice>
944     <guimenu>Map</guimenu>
945     <guimenuitem>Export</guimenuitem>
946     </menuchoice> for use in reports, presentations, or further
947     modification. The current map view, legend, and, if available,
948     scalebar are exported. Under other platforms this option is not
949     available. Clicking this menu item open a file selection dialog
950     that lets the user select a location to export the map.
951     </para>
952     </section>
953    
954     <section><title>Printing</title>
955     <para>
956     The map can be printed using
957     <menuchoice>
958     <guimenu>Map</guimenu>
959     <guimenuitem>Print</guimenuitem>
960     </menuchoice>. The current map view, legend, and, if available,
961     scalebar are printed. A standard printing dialog will open allowing
962     the user to configure the printer. This dialog will differ depending
963     on which platform Thuban is running.
964     </para>
965     </section>
966    
967     </chapter>
968    
969     <chapter><title>Layer Management</title>
970     <para>
971     </para>
972    
973     <section><title>Types of Layers</title>
974     <para>
975     There are three types of layers supported by Thuban: shape layers,
976     database layers and
977     image layers. Shape layers consist of vector based shapes with
978     geo-referenced coordinates. There are three types of supported
979     shapes: polygons, lines (arc), and points. Database layers are similar
980     to shape layers but loaded from a database instead of the file system.
981     Image layers can be any image
982     file format supported by the Geo-spatial Data Abstraction Library
983     (GDAL). The images must have geographic
984     coordinate data either embedded within the file or in a separate
985     file that is in the same directory as the image file. GeoTIFF files
986     work very well with Thuban and were designed specifically to be image
987     layers in GIS programs.
988     </para>
989     <para>
990     All actions in the
991     <menuchoice>
992     <guimenu>Layer</guimenu>
993     </menuchoice> menu act on the currently selected layer in the legend.
994     </para>
995     </section>
996    
997     <section><title>Properties</title>
998     <para>
999     To view the properties for a layer it must first be selected in the
1000     legend. The menu option
1001     <menuchoice>
1002     <guimenu>Layer</guimenu>
1003     <guimenuitem>Properties</guimenuitem>
1004     </menuchoice> opens a dialog that displays a layer's properties.
1005     All layers have a title which can be modified in the text field
1006     provided. The type of layer is also shows. If the type is a type
1007     of shape (polygon, arc, point) the classification table will be
1008     shown. Image layers have no other properties other than title
1009     and type.
1010     </para>
1011     <para>
1012     <figure>
1013     <title>Properties Window</title>
1014     <mediaobject>
1015     <imageobject><imagedata fileref="../images/4_2_layer_properties.png" format="PNG" scale="&imgscale;"/></imageobject>
1016     <imageobject><imagedata fileref="./images/4_2_layer_properties.eps" format="EPS" scale="&imgscale;"/></imageobject>
1017     </mediaobject>
1018     </figure>
1019     </para>
1020     <para>
1021     <figure>
1022     <title>Properties Window</title>
1023     <mediaobject>
1024     <imageobject><imagedata fileref="../images/4_2_raster_layer_properties.png" format="PNG" scale="&imgscale;"/></imageobject>
1025     <imageobject><imagedata fileref="./images/4_2_raster_layer_properties.eps" format="EPS" scale="&imgscale;"/></imageobject>
1026     </mediaobject>
1027     </figure>
1028     </para>
1029     </section>
1030    
1031     <section><title>Visibility</title>
1032     <para>
1033     Sometimes it is not desirable to view all layers at the same time.
1034     Some layers may take a long time to draw and so while navigating
1035     around the map the user may not want to wait for the map to redraw
1036     all the layers each time the map is changed. Each layer can be
1037     independently turned on or off using the
1038     <menuchoice>
1039     <guimenu>Layer</guimenu>
1040     <guimenuitem>Show</guimenuitem>
1041     </menuchoice>
1042     or
1043     <menuchoice>
1044     <guimenu>Layer</guimenu>
1045     <guimenuitem>Hide</guimenuitem>
1046     </menuchoice> options respectively.
1047     </para>
1048     </section>
1049    
1050     <section><title>Duplication</title>
1051     <para>
1052     Layers and all their properties, including classifications, can
1053     be duplicated using
1054     <menuchoice>
1055     <guimenu>Layer</guimenu>
1056     <guimenuitem>Duplicate</guimenuitem>
1057     </menuchoice>. Duplicating a layer is useful if the user wishes
1058     to model a layer in several different ways. Even though the layers
1059     overlap, by carefully selecting the shape properties it is possible
1060     to display several pieces of information at once. For example, one
1061     copy of a roads layer may be classified on a length property and
1062     another copy may be classified on a type property. If the length
1063     property was expressed with color and the type property expressed
1064     with line thickness then it would be possible to view both
1065     classifications by placing the type property copy over the
1066     length property copy.
1067     </para>
1068     </section>
1069    
1070     </chapter>
1071    
1072     <chapter><title>Layer Classifications</title>
1073     <para>
1074     A layer classification is a way of assigning drawing properties to
1075     groups of shapes based on attributes stored in the layer's table.
1076     Only layer's with shapes can have a classification; image layers
1077     cannot be classified.
1078     </para>
1079     <para>
1080     A classification consists of a number of groups, each group
1081     having a value or range of values to match against, and symbol
1082     properties which control how a shape is drawn on the map. The user
1083     selects which field in the table is used by the classification and
1084     when the map is drawn the value for that field for each shape is
1085     compared with each group's value. The properties of the first group
1086     to match are used to draw the shape. This allows the user to get a
1087     visual impression of not only how the data is laid out but also what
1088     kind of data lies where.
1089     </para>
1090     <para>
1091     A layer always has a classification. When a new layer is added to the
1092     map, a default classification is created with the DEFAULT group. This
1093     group cannot be removed but can be hidden (see below). Every shape in the
1094     layer, regardless of its attributes, will match this group if no other
1095     group matches.
1096     </para>
1097    
1098     <section><title>Editing Classifications</title>
1099     <para>
1100     A layer's classification can be modified under the properties dialog
1101     (<menuchoice>
1102     <guimenu>Layer</guimenu>
1103     <guimenuitem>Properties</guimenuitem>
1104     </menuchoice>). The layer's classification field can be set to None,
1105     which simply assigns a DEFAULT group to the classification. No new
1106     groups can be added to the classification if the field is None.
1107     The user must first select a field to classify on. New groups can
1108     be added to the classification with the <guibutton>Add</guibutton>
1109     button.
1110     </para>
1111     <para>
1112     To apply the changes to the map the user can click
1113     either <guibutton>Try</guibutton> or <guibutton>OK</guibutton>.
1114     <guibutton>Try</guibutton> will not close the dialog box, allowing
1115     the user to see how the classification changes the map.
1116     <guibutton>Revert</guibutton> will undo the last classification applied
1117     to the map. <guibutton>OK</guibutton> will commit the changes and
1118     close the dialog. The user will be unable to undo the changes.
1119     <guibutton>Close</guibutton> simply closes the dialog box. If any
1120     changes have not been applied with <guibutton>Try</guibutton> the
1121     changes will not be applied to the map.
1122     </para>
1123     <para>
1124     <figure>
1125     <title>Properties Window</title>
1126     <mediaobject>
1127     <imageobject><imagedata fileref="../images/5_classification.png" format="PNG" scale="&imgscale;"/></imageobject>
1128     <imageobject><imagedata fileref="./images/5_classification.eps" format="EPS" scale="&imgscale;"/></imageobject>
1129     </mediaobject>
1130     </figure>
1131     </para>
1132     <para>
1133     The order of the groups in the classification is significant
1134     except for the DEFAULT group, which remains at the top. When shapes
1135     are matched against groups the matching begins at the first group
1136     after the DEFAULT group so that groups higher in the list will
1137     be checked first. Matching for a
1138     given shape will stop at the first group that matches. The user can
1139     use <guibutton>Move Up</guibutton> and <guibutton>Move Down</guibutton>
1140     to change the order of the groups. The DEFAULT group will always
1141     match a shape that hasn't matched another group.
1142     </para>
1143     <section><title>Visible</title>
1144     <para>
1145     The Visible column has check-boxes that determine whether a
1146     classification group will be displayed in the legend. This is
1147     useful if the user knows that the groups completely cover
1148     the data set and don't want the DEFAULT group to be displayed
1149     in the legend and on a printout.
1150     </para>
1151     </section>
1152     <section><title>Symbols</title>
1153     <para>
1154     Each type of shape has its own type of symbol. Thuban supports three
1155     types of shapes: polygons, lines, and points. Polygons and points
1156     have outline and fill color, while lines have only line color. Each
1157     group has associated symbol properties. To edit the symbol
1158     properties for a group the user can double click on the Symbol
1159     column or select a group and click the
1160     <guibutton>Edit Symbol</guibutton> button.
1161     </para>
1162     </section>
1163     <section><title>Value</title>
1164     <para>
1165     The Value column of the classification table is the value that will
1166     be matched when the map is being drawn. The type of data that can
1167     entered into this field depends on the type of data of the
1168     classification field.
1169     </para>
1170     <para>
1171     If the field is of type Text, anything entered
1172     into the field is valid. The text will be compared literally to the
1173     value of the shape attribute, including case sensitivity.
1174     If the type is Integer, then any valid integer may be entered. In
1175     addition, with special syntax, a range of values can be entered.
1176     A range from <varname>start</varname> to <varname>end</varname>
1177     inclusive is specified like this: <literal>[start;end]</literal>.
1178     The exclusive range is specified like this:
1179     <literal>]start;end[</literal>. Ranges can include infinity like
1180     this: <literal>[-oo;oo]</literal>. Field types can also be of type
1181     Decimal. They represent any rational number and can be used in
1182     ranges as well.
1183     </para>
1184     </section>
1185     <section><title>Label</title>
1186     <para>
1187     By default, the text that is displayed for a group in the legend
1188     is the value for that group. The label can substitute a more
1189     descriptive term in the legend.
1190     </para>
1191     </section>
1192     </section>
1193    
1194     <section><title>Generating Classes</title>
1195     <para>
1196     <figure>
1197     <title>Generate Class</title>
1198     <mediaobject>
1199     <imageobject><imagedata fileref="../images/5_3_genclass.png" format="PNG" scale="&imgscale;"/></imageobject>
1200     <imageobject><imagedata fileref="./images/5_3_genclass.eps" format="EPS" scale="&imgscale;"/></imageobject>
1201     </mediaobject>
1202     </figure>
1203     </para>
1204     <para>
1205     Creating a classification by hand can be tedious.
1206     Thuban, therefore, provides a means of generating an entire
1207     classification at once while still giving the user control over
1208     how it appears. Clicking <guibutton>Generate Class</guibutton>
1209     opens the <varname>Generate Classification</varname> dialog.
1210     Under the <varname>Generate</varname> pull down there are at most
1211     three different ways to generate classifications:
1212     Unique Values, Uniform Distribution, and Quantiles. Some options
1213     may not be available if the data type for the field does not
1214     support them. For instance, <varname>Uniform Distribution</varname>
1215     doesn't make sense for a Text field.
1216     </para>
1217     <para>
1218     For every way of generating a classification, a color scheme must
1219     be selected. Thuban provides several different color schemes that
1220     affect how the group properties change over the classification.
1221     It may be desirable that only certain properties change over the
1222     classification. If the shape type is a polygon or a point then
1223     the <guibutton>Fix Border Color</guibutton> option will be available.
1224     This allows the user to select a border color for all classification
1225     groups.
1226     It is also possible to create a custom color scheme. Selecting
1227     this option will display two symbols: the one of the left has the
1228     properties of the first group and the one on the right has the
1229     properties of the last group. Thuban will interpolate between these
1230     two properties to generate the other groups.
1231     <figure>
1232     <title>Custom Color Scheme</title>
1233     <mediaobject>
1234     <imageobject><imagedata fileref="../images/5_2_custom_ramp.png" format="PNG" scale="&imgscale;"/></imageobject>
1235     <imageobject><imagedata fileref="./images/5_2_custom_ramp.eps" format="EPS" scale="&imgscale;"/></imageobject>
1236     </mediaobject>
1237     </figure>
1238     </para>
1239     <para>
1240     The Unique Values option lets the user select specific values that
1241     appear in the table. Clicking <guibutton>Retrieve From Table</guibutton>
1242     searches the table for all unique values and displays them in the
1243     list on the left. Items can be selected and moved to the list on the
1244     right. Each list can be sorted or reversed for easier searching.
1245     The classification that is generated will be in the same order as
1246     the list on the right.
1247     <figure>
1248     <title>Unique Values</title>
1249     <mediaobject>
1250     <imageobject><imagedata fileref="../images/5_2_unique_values.png" format="PNG" scale="&imgscale;"/></imageobject>
1251     <imageobject><imagedata fileref="./images/5_2_unique_values.eps" format="EPS" scale="&imgscale;"/></imageobject>
1252     </mediaobject>
1253     </figure>
1254     </para>
1255     <para>
1256     The Uniform Distribution option creates a user specified number of
1257     groups of ranges such that each range covers equal intervals. The
1258     minimum and maximum values can automatically be retrieved from the
1259     table by clicking <guibutton>Retrieve From Table</guibutton>. The
1260     stepping is how large each interval is. Adjusting this value will
1261     automatically recalculate how many groups is appropriate.
1262     <figure>
1263     <title>Uniform Distribution</title>
1264     <mediaobject>
1265     <imageobject><imagedata fileref="../images/5_2_uniform_dist.png" format="PNG" scale="&imgscale;"/></imageobject>
1266     <imageobject><imagedata fileref="./images/5_2_uniform_dist.eps" format="EPS" scale="&imgscale;"/></imageobject>
1267     </mediaobject>
1268     </figure>
1269     </para>
1270     <para>
1271     The Quantiles option generates ranges based on the number of items
1272     in the table. For example, by specifying five groups Thuban will
1273     generate five groups with appropriate ranges such that 20% of the table
1274     data is in each group. If it is impossible to generate exact
1275     groupings, Thuban will issue a warning but allow the user to continue.
1276     <figure>
1277     <title>Quantiles</title>
1278     <mediaobject>
1279     <imageobject><imagedata fileref="../images/5_2_quantiles.png" format="PNG" scale="&imgscale;"/></imageobject>
1280     <imageobject><imagedata fileref="./images/5_2_quantiles.eps" format="EPS" scale="&imgscale;"/></imageobject>
1281     </mediaobject>
1282     </figure>
1283     </para>
1284     </section>
1285     </chapter>
1286    
1287     <chapter><title>Projection Management</title>
1288     <para>
1289     Projections control how the geographic data is displayed on the screen.
1290     If multiple layers are loaded into Thuban where the geographic data
1291     is in a different projection system, then the user must specify a
1292     projection for each layer. The user must also tell Thuban which
1293     projection the map is in. This can be the same as the layers or a different
1294     projection in which case the layers are reprojected into that space.
1295     The map projection can be set using
1296     <menuchoice>
1297     <guimenu>Map</guimenu>
1298     <guimenuitem>Projection</guimenuitem>
1299     </menuchoice> and the layer projection can be set using
1300     <menuchoice>
1301     <guimenu>Layer</guimenu>
1302     <guimenuitem>Projection</guimenuitem>
1303     </menuchoice>.
1304     <figure>
1305     <title>Projection Window</title>
1306     <mediaobject>
1307     <imageobject><imagedata fileref="../images/6_projection.png" format="PNG" scale="&imgscale;"/></imageobject>
1308     <imageobject><imagedata fileref="./images/6_projection.eps" format="EPS" scale="&imgscale;"/></imageobject>
1309     </mediaobject>
1310     </figure>
1311     </para>
1312     <para>
1313     Thuban is distributed with a sample collection of projections and the
1314     set of coordinate systems as used by the EPSG
1315     (European Petroleum Survey Group). This quite large set is only displayed
1316     if activated by the according checkbox. The set falls into two parts:
1317     deprecated lists all projections which are no longer part of the
1318     EPSG data base.
1319     </para>
1320     <para>
1321     The
1322     user can create new projections and make them available to all
1323     future Thuban sessions. They may also be exported and imported so
1324     that custom projections can be distributed.
1325     </para>
1326     <section><title>Selecting a Projection</title>
1327     <para>
1328     The available projections are listed on the left. If the layer
1329     or map already has a projection it will initially be highlighted
1330     and will end with <varname>(current)</varname>. Selecting
1331     <varname>&lt;None&gt;</varname> will cause Thuban to use the data as
1332     it appears in the source file and will not use a projection.
1333     </para>
1334     </section>
1335     <section><title>Editing a Projection</title>
1336     <para>
1337     Whenever a projection is selected from the list its properties
1338     are displayed on the right. These properties can be changed
1339     and the changes saved to the selected projection using
1340     <guibutton>Update</guibutton>. Only a projection that comes
1341     from a file can be updated, so if the current layer's projection
1342     is selected, <guibutton>Update</guibutton> will be disabled.
1343     <guibutton>Add to List</guibutton> adds the projection to the
1344     list of available projections as a new entry, and thus makes it
1345     available to future Thuban sessions. Clicking <guibutton>New</guibutton>
1346     will create an entirely new, empty projection. The
1347     <guibutton>Remove</guibutton> button will permanently remove a
1348     projection from the list of available projections.
1349     </para>
1350     <para>
1351     To apply the selected projection to the map the user can click
1352     either <guibutton>Try</guibutton> or <guibutton>OK</guibutton>.
1353     <guibutton>Try</guibutton> will not close the dialog box, allowing
1354     the user to see how the projeciton changes the map.
1355     <guibutton>Revert</guibutton> will undo the last projection applied
1356     to the map. <guibutton>OK</guibutton> will commit the changes and
1357     close the dialog. The user will be unable to undo the changes.
1358     <guibutton>Close</guibutton> simply closes the dialog box. If no
1359     selection has been applied with <guibutton>Try</guibutton> the
1360     selection will not be applied to the map.
1361     </para>
1362     </section>
1363     <section><title>Importing/Exporting Projections</title>
1364     <para>
1365     The projections that appear in the list of available projections
1366     can be exported to another file that the user chooses. By selecting
1367     one or more projections and clicking <guibutton>Export</guibutton>
1368     the user will be able to select a file in which to store those
1369     projections.
1370     The file can then be distributed to other Thuban users. To import
1371     a projection file the user can click <guibutton>Import</guibutton>.
1372     The imported projections are added to the list and are then available
1373     to the current session and any future Thuban sessions.
1374     </para>
1375     </section>
1376     </chapter>
1377    
1378     <chapter><title>Table Management</title>
1379     <para>
1380     Thuban distinguishes two different types of tables: Attribute tables
1381     (which belong to a layer) and normal data tables. Both provide
1382     the same general functionality with the difference that actions on an
1383     attribute table might also effect the map display.
1384     </para>
1385    
1386     <section><title>Table View</title>
1387     <para>
1388     <figure>
1389     <title>Table View</title>
1390     <mediaobject>
1391     <imageobject><imagedata fileref="../images/7_1_table_view.png" format="PNG" scale="&imgscale;"/></imageobject>
1392     <imageobject><imagedata fileref="./images/7_1_table_view.eps" format="EPS" scale="&imgscale;"/></imageobject>
1393     </mediaobject>
1394     </figure>
1395     </para>
1396     <para>
1397     Thuban provides a standard dialog to display table contents, the
1398     Table View. The view has five sections: The title, selections,
1399     the table grid, export functions, and the status bar.
1400     </para>
1401     <para>
1402     The title bar identifies the table with its name.
1403     </para>
1404     <para>
1405     The selections box let the user perform simple analysis on the data
1406     based on comparisons: The first choice must be a field identifier of
1407     the table, the second choice determines the type of comparison. The
1408     third choice can be either a specific value (interpreted as numerical
1409     or string depending on the type of the first field) or a second field
1410     identifier. Thus you can perform analysis like selecting all
1411     records where <literal>population > 10000</literal> or
1412     <literal>cars_per_inhabitant < bikes_per_inhabitant</literal>
1413     (note that the field names are only explanatory, the dBase files
1414     allow only 11 character field names).
1415    
1416     Selections can be combined either by applying a selection only on
1417     a previously selected set of records or by adding the results of a
1418     selection to a previous set. The default is that a selection replaces
1419     earlier results.
1420     </para>
1421     <para>
1422     The table grid shows the contents of the table (one record per row),
1423     with highlighted selection results. Columns and rows can be resized.
1424     </para>
1425     <para>
1426     The contents of a table can be exported into a file, either dBase
1427     format (DBF) or comma separated values (CSV). The
1428     <guibutton>Export</guibutton> button
1429     raises a file dialog to specify a path and file name, the export type
1430     is determined by the file extension (either .dbf or .csv).
1431    
1432     The <guibutton>Export Selection</guibutton> button works similarly
1433     but exports only the selected records.
1434    
1435     The <guibutton>Close</guibutton> button closes the table view window.
1436     This is different from the menu item
1437     <menuchoice>
1438     <guimenu>Table</guimenu>
1439     <guimenuitem>Close</guimenuitem>
1440     </menuchoice> which unloads the table from Thuban.
1441     </para>
1442     <para>
1443     The status bar displays some statistics about the table and optional
1444     selection results.
1445     </para>
1446     </section>
1447    
1448     <section><title>General Functionality (Menu Table)</title>
1449     <para>
1450     The general functions affect all tables open in Thuban. Attribute
1451     tables are considered here as normal data tables (with the exception
1452     that they cannot be closed).
1453     </para>
1454     <section><title>Open</title>
1455     <para>
1456     The
1457     <menuchoice>
1458     <guimenu>Table</guimenu>
1459     <guimenuitem>Open</guimenuitem>
1460     </menuchoice>
1461     item raises a file dialog to let you select a
1462     dBase file from the file system to be loaded into Thuban read-only.
1463     On <guibutton>OK</guibutton> the selected file is loaded and a
1464     table view is opened.
1465     </para>
1466     </section>
1467    
1468     <section><title>Close</title>
1469     <para>
1470     The
1471     <menuchoice>
1472     <guimenu>Table</guimenu>
1473     <guimenuitem>Close</guimenuitem>
1474     </menuchoice>
1475     item raises a dialog listing the currently open
1476     data tables
1477     (loaded via
1478     <menuchoice>
1479     <guimenu>Table</guimenu>
1480     <guimenuitem>Open</guimenuitem>
1481     </menuchoice>). Selected tables are dereferenced on confirmation.
1482     Since tables are opened read-only the contents of the tables are
1483     not affected.
1484    
1485     Any open views of the tables are closed as well.
1486    
1487     Tables used in a join cannot be closed.
1488     </para>
1489     </section>
1490    
1491     <section><title>Rename</title>
1492     <para>
1493     <menuchoice>
1494     <guimenu>Table</guimenu>
1495     <guimenuitem>Rename</guimenuitem>
1496     </menuchoice> changes the table title.
1497     </para>
1498     </section>
1499    
1500     <section><title>Show</title>
1501     <para>
1502     The
1503     <menuchoice>
1504     <guimenu>Table</guimenu>
1505     <guimenuitem>Show</guimenuitem>
1506     </menuchoice>
1507     item raises a list of available tables (explicitly
1508     loaded, attribute tables, results of a join). Selected tables are
1509     show in tables views on <guibutton>OK</guibutton>.
1510     </para>
1511     </section>
1512    
1513     <section><title>Join</title>
1514     <para>
1515     <figure>
1516     <title>Join Tables</title>
1517     <mediaobject>
1518     <imageobject><imagedata fileref="../images/7_2_5_join.png" format="PNG" scale="&imgscale;"/></imageobject>
1519     <imageobject><imagedata fileref="./images/7_2_5_join.eps" format="EPS" scale="&imgscale;"/></imageobject>
1520     </mediaobject>
1521     </figure>
1522     </para>
1523     <para>
1524     The
1525     <menuchoice>
1526     <guimenu>Table</guimenu>
1527     <guimenuitem>Join</guimenuitem>
1528     </menuchoice>
1529     item raises a dialog to specify the two tables to be
1530     joined. The join results in a new table named 'Join of "left table"
1531     and "right table"'.
1532    
1533     The dialog lets you select the two tables to be joined and the two
1534     fields the join has to be performed on. By default, the new
1535     table contains only those records which are matched by the join.
1536    
1537     If you want to preserve the records of the left table you can
1538     perform an outer join. The fields from the right table for records
1539     not matched by the join are filled with <varname>None</varname> in
1540     this case.
1541     </para>
1542     </section>
1543    
1544     </section>
1545     <section><title>Attribute Tables</title>
1546     <para>
1547     To clearly separate between both types of tables (data and
1548     attribute), Thuban provides functionality regarding the attribute
1549     tables under the <menuchoice><guimenu>Layer</guimenu></menuchoice> menu.
1550     </para>
1551    
1552     <section><title>Show Table</title>
1553     <para>
1554     <menuchoice>
1555     <guimenu>Layer</guimenu>
1556     <guimenuitem>Show Table</guimenuitem>
1557     </menuchoice>
1558     opens the attribute table of the currently active layer in a table
1559     view.
1560    
1561     In addition to the functionality described above selections
1562     affect also the map display: objects related to selected records
1563     are highlighted.
1564     </para>
1565     </section>
1566    
1567     <section><title>Join Table</title>
1568     <para>
1569     Unlike the join described above, the join does not result in a
1570     new table. The attribute table of the currently active layer is the
1571     left table and other tables are joined to this table. The results of
1572     the join are available for classification.
1573    
1574     As a consequence, the join cannot result in fewer
1575     records than the source attribute table. The user is warned if the
1576     right table does not fulfill this constraint. An outer join must be
1577     used in such cases.
1578     </para>
1579     </section>
1580    
1581     <section><title>Unjoin Table</title>
1582     <para>
1583     As said above, a normal table cannot be closed while it is still
1584     used in a join. While the joined table resulting from a join of
1585     normal tables can be simply closed (and thereby dereferencing
1586     the source tables), this is not possible for attribute tables.
1587    
1588     Hence joins on attribute tables must be solved explicitly. This is
1589     what the
1590     <menuchoice>
1591     <guimenu>Layer</guimenu>
1592     <guimenuitem>Unjoin Table</guimenuitem>
1593     </menuchoice>
1594     item is used for: The last join for the currently
1595     active layer is solved.
1596     </para>
1597     </section>
1598     </section>
1599     </chapter>
1600    
1601     <chapter><title>Extensions</title>
1602     <para>
1603     Thuban is designed to be extensible. The term Extension is used as a
1604     general term for anything that extends Thuban.
1605     This chapter introduces into some oppportunities how to add and
1606     handle extra functionality developed by your own or third parties.
1607     </para>
1608    
1609     <section><title>Add personal extensions via thubanstart.py</title>
1610     <para>
1611     After Thuban has been started for the first time, a directory
1612     .thuban is created within your home directory.
1613     There you can add a file thubanstart.py which will be imported
1614     by Thuban at start-up. It is recommended to add only import-statements
1615     to this file to keep the actual code of extensions separate.
1616     </para>
1617     <para>
1618     The modules to import must either be found through the environment
1619     variable PYTHONPATH or directly be placed into the .thuban-directory.
1620     </para>
1621     <para>
1622     As an example, copy the file examples/simple_extensions/hello_world.py
1623     of the Thuban source code into the .thuban-directory of your home
1624     directory. Now add add the statement import hello_world to the
1625     file thubanstart.py and run Thuban. You will notice an additional
1626     menu <menuchoice><guimenu>Extensions</guimenu></menuchoice> where
1627     the new item for the Hello-World extension is placed - select it
1628     to see the Hello-World message.
1629     </para>
1630     </section>
1631    
1632     <section><title>Extensions included in Thuban package</title>
1633     <para>
1634     The extensions described in this section are part of the
1635     Thuban package, but not activated by default.
1636     You will find them in the Thuban installation directory
1637     under <literal>Extensions/</literal>. Activate them as personal
1638     extensions via PYTHONPATH as described in the previous section.
1639     Stable extensions will appear under the menu
1640     <menuchoice><guimenu>Extensions</guimenu></menuchoice> and
1641     extensions which are in experimental state and therefore
1642     not fully functional under
1643     <menuchoice><guimenu>Experimental</guimenu></menuchoice>.
1644     </para>
1645    
1646     <section><title>Stable extensions</title>
1647     <para>
1648     These extensions provide extra-functionality to Thuban
1649     that has not (yet) been integrated in the main application.
1650     They are considered to be free of bugs, but may be
1651     further polished with helpful user interactions.
1652     </para>
1653     <section><title>gns2shp</title>
1654     <para>
1655     This tool converts data of the Geospatial Names Server
1656     (GNS, see <ulink url="http://www.nima.mil/gns"/>)
1657     into Shapefile format.
1658     The above web-site offer to download named places
1659     information grouped by countries for all of the world
1660     except USA for which other data are provided.
1661     </para>
1662     <para>
1663     If you download and unpack a package, you will have
1664     a text-file with suffix .txt.
1665     Selecting such a file via gns2shp will create the
1666     corresponding Shapefile with the same basename and
1667     place it in the same direcory. Afterwards it
1668     is automatically loaded into Thuban.
1669     The Shapefile will not automatically be delete afterwards.
1670     </para>
1671     <para>
1672     The gns2shp.py module can also be executed on the
1673     command line for batch processing purposes.
1674     </para>
1675     <para>
1676     A sample (<literal>ls.txt</literal> for Liechtenstein)
1677     is included in the directory
1678     <literal>Extensions/gns2shp/test</literal>.
1679     </para>
1680     </section>
1681     </section>
1682     <section><title>Experimental extensions</title>
1683     <para>
1684     All all of these functions have to be handled with care,
1685     since they are neither complete nor well tested.
1686     They are to be seen as a proof-of-concept and may
1687     additionally in some cases of practical help.
1688     </para>
1689     <para>
1690     Any interest on further improvement of these extensions
1691     should be communicated towards the developer and user
1692     community.
1693     </para>
1694    
1695     <section><title>importAPR</title>
1696     <para>
1697     This command offer to load an ESRI® ArcView® project
1698     file (suffix .apr) and convert it for use within Thuban.
1699     After selecting a apr-file to load, a list
1700     will be presented that offers to select one of the views
1701     of the apr-file, provided there is more than one.
1702     Furthermore, the Session Info-Tree is extended with
1703     a complete representation of the parsed apr-file.
1704     </para>
1705     <para>
1706     The legend of Thuban does not yet cover all of the elements as
1707     supported by the legend of ArcView®. Therefore, the Thuban
1708     map will look different. Furthermore, the apr-format is
1709     a proprietary format, not openly documented.
1710     Therefore, the interpretation is
1711     partly based on reverse engeneering and good guessing.
1712     </para>
1713     <para>
1714     The file-paths within the apr-file may not fit and potentially
1715     are subject to fix in the apr-file. You can do this
1716     applying any text editor. The paths are either absolute
1717     or relative from where Thuban has been started.
1718     </para>
1719     <para>
1720     A sample for the Iceland data is included as
1721     <literal>Extensions/importAPR/samples/iceland.apr</literal>.
1722     The file-paths are relative from the Thuban main directory.
1723     </para>
1724     </section>
1725     </section>
1726     </section>
1727    
1728     <section><title>Writing simple extensions</title>
1729     <para>
1730     Writing an extension for Thuban basically means to
1731     implement the extra functionality in Python with all of the
1732     Thuban classes, methods and variables available.
1733     </para>
1734     <para>
1735     All classes and their methods are documented in the source code
1736     (see their doc-strings). Here is an example from
1737     Thuban/Model/layer.py that describes some of the methods
1738     of a Layer object:
1739     </para>
1740     <programlisting>
1741     <![CDATA[
1742     class BaseLayer(TitledObject, Modifiable):
1743    
1744     """Base class for the layers."""
1745    
1746     def __init__(self, title, visible = True, projection = None):
1747     """Initialize the layer.
1748    
1749     title -- the title
1750     visible -- boolean. If true the layer is visible.
1751     """
1752     TitledObject.__init__(self, title)
1753     Modifiable.__init__(self)
1754     self.visible = visible
1755     self.projection = projection
1756    
1757     def Visible(self):
1758     """Return true if layer is visible"""
1759     return self.visible
1760    
1761     def SetVisible(self, visible):
1762     """Set the layer's visibility."""
1763     self.visible = visible
1764     self.issue(LAYER_VISIBILITY_CHANGED, self)
1765    
1766     def HasClassification(self):
1767     """Determine if this layer support classifications."""
1768     ...
1769     ]]>
1770     </programlisting>
1771     <para>
1772     This example intends to give you an impression of the
1773     source-code-level documentation.
1774     You have to make yourself familiar with
1775     the Python programming language to understand some special
1776     code elements.
1777     </para>
1778     <section><title>hello_world.py</title>
1779     <para>
1780     Traditionally, the first example should welcome the world.
1781     Most of the code handles the frame for integrating a menu
1782     item into Thuban while the actual raising of a message
1783     is done in a single line.
1784     </para>
1785     <programlisting>
1786     <![CDATA[
1787     # Copyright (C) 2003 by Intevation GmbH
1788     # Authors:
1789     # Jan-Oliver Wagner <[email protected]>
1790     #
1791     # This program is free software under the GPL (>=v2)
1792     # Read the file COPYING coming with Thuban for details.
1793    
1794     """
1795     Extend Thuban with a sample Hello World to demonstrate simple
1796     extensions.
1797     """
1798    
1799     __version__ = '$Revision$'
1800    
1801     # use _() already now for all strings that may later be translated
1802     from Thuban import _
1803    
1804     # Thuban has named commands which can be registered in the central
1805     # instance registry.
1806     from Thuban.UI.command import registry, Command
1807    
1808     # The instance of the main menu of the Thuban application
1809     # See Thuban/UI/menu.py for the API of the Menu class
1810     from Thuban.UI.mainwindow import main_menu
1811    
1812     def hello_world_dialog(context):
1813     """Just raise a simple dialog to greet the world.
1814    
1815     context -- The Thuban context.
1816     """
1817     context.mainwindow.RunMessageBox(_('Hello World'), _('Hello World!'))
1818    
1819    
1820     # create a new command and register it
1821     registry.Add(Command('hello_world', _('Hello World'), hello_world_dialog,
1822     helptext = _('Welcome everyone on this planet')))
1823    
1824     # find the extensions menu (create it anew if not found)
1825     extensions_menu = main_menu.FindOrInsertMenu('extensions', _('E&xtensions'))
1826    
1827     # finally bind the new command with an entry in the extensions menu
1828     extensions_menu.InsertItem('hello_world')
1829     ]]>
1830     </programlisting>
1831     </section>
1832     <section><title>Registering a Command</title>
1833     <para>
1834     Mainly, our new function has to be registered to the Thuban
1835     framework in order to connect it to the menu. A registered
1836     command can also be connected to e.g. a toolbar button.
1837     </para>
1838     <para>
1839     The instances and classes for this are imported at the beginning.
1840     Any code not inside a method or class is directly executed when
1841     the source-code module is imported. Therefore, the second
1842     part of this example consist of the plain statements to create a new
1843     Command and to add it to the menu.
1844     </para>
1845     <para>
1846     By convention, it looks for a menu registered as ``extensions'' to
1847     insert the new command. If it does not exist yet, it gets created.
1848     It is advisable to copy this code for any of your extensions.
1849     </para>
1850     </section>
1851     <section><title>The Thuban context</title>
1852     <para>
1853     A registered command that is called, always receives the
1854     Thuban context. This instance provides our method with
1855     hook references to all important components of the Thuban
1856     application.
1857     </para>
1858     <para>
1859     In the example hello_world.py, our function uses the
1860     mainwindow component which offers a method to raise a
1861     message dialog. In total there are three hooks:
1862     <itemizedlist>
1863     <listitem>
1864     <para>application:
1865     This object is the instance of the Thuban Application class.
1866     Except maybe for loading or savinf sessions, you will not
1867     need this object for a simple extension.
1868     See Thuban/UI/application.py for the API.
1869     </para>
1870     </listitem>
1871     <listitem>
1872     <para>session:
1873     The instance of the current session. It manages the sessions'
1874     map and tables. You can set and remove the map or tables.
1875     In may also get the map object. However, you should know that
1876     internally it is already prepared to handle many maps.
1877     Therfore, currently you would always receive a list with exactlty
1878     one element. In the future, if there are more than one map,
1879     you will not know which one is the currently display one and
1880     therefore you should use the mainwindow as hook to find
1881     the currently displayed map.
1882     See Thuban/Model/session.py for the API.
1883     </para>
1884     </listitem>
1885     <listitem>
1886     <para>
1887     mainwindow: The mainwindow object is central to manage various
1888     GUI things such as the Legend sub-window. Most notably,
1889     you get access to the canvas which is the window part where
1890     the map is drawn. The canvas knows, which map it currently
1891     draws and therefore you get the current map via
1892     context.mainwindow.canvas.Map().
1893     See Thuban/UI/mainwindow.py for the API.
1894     </para>
1895     </listitem>
1896     </itemizedlist>
1897     </para>
1898     </section>
1899     </section>
1900     </chapter>
1901    
1902     <chapter><title>Trouble Shooting</title>
1903     <para>
1904     Here are a few problems that users have encountered when first using Thuban.
1905     </para>
1906     <para>
1907    
1908     <itemizedlist>
1909     <listitem>
1910     <para>After adding two or more layers nothing is drawn in the map window.
1911     </para>
1912     <para>
1913     This is probably because the layers have different projections. Projections
1914     must be set on all layers and on the map itself if the layers' projections
1915     are different.
1916     </para>
1917     </listitem>
1918    
1919     <listitem>
1920     <para>Thuban crashes on startup with the error
1921     <literal>NameError: global name 'False' is not defined</literal>.
1922     </para>
1923     <para>
1924     <varname>True</varname> and <varname>False</varname> were only introduced
1925     in Python 2.2.1. Thuban depends on at least Python 2.2.1.
1926     </para>
1927     </listitem>
1928    
1929     <listitem>
1930     <para>After compiling Thuban, Thuban crashes with an error similar to
1931     <literal>
1932     ImportError: /usr/local//lib/thuban/Thuban/../Lib/wxproj.so: undefined symbol: __gxx_personality_v0
1933     </literal>
1934     </para>
1935     <para>
1936     Thuban depends on the wxWindows library. If Thuban is compiled with an
1937     incompatible version of the compiler than wxWindows was compiled with
1938     this error may occur. Try compiling with a different version of the
1939     compiler.
1940     </para>
1941     </listitem>
1942     </itemizedlist>
1943     </para>
1944     <para>
1945     If an error occurs Thuban will display a dialog indicating the error
1946     before closing. The text should be copied and reported to the
1947     <ulink url="http://thuban.intevation.org/bugtracker.html">
1948     Intevation bugtracker
1949     </ulink>.
1950     More information about the system is available from
1951     <menuchoice><guimenu>Help</guimenu><guimenuitem>About</guimenuitem></menuchoice> box.
1952     This should also be included in the bug report.
1953     <figure>
1954     <title>Error Dialog</title>
1955     <mediaobject>
1956     <imageobject><imagedata fileref="../images/8_int_error.png" format="PNG" scale="&imgscale;"/></imageobject>
1957     <imageobject><imagedata fileref="./images/8_int_error.eps" format="EPS" scale="&imgscale;"/></imageobject>
1958     </mediaobject>
1959     </figure>
1960     </para>
1961    
1962     </chapter>
1963    
1964     <appendix><title>Supported Data Sources</title>
1965     <para>
1966     </para>
1967     <variablelist>
1968     <varlistentry>
1969     <term>Shapefile</term>
1970     <listitem>
1971     <para>
1972     The Shapefile format has become a standard format for saving
1973     geographic vector information. It supports polygons, lines, and
1974     points.
1975    
1976     <ulink url="http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf">
1977     Technical Specification.
1978     </ulink>
1979     </para>
1980     </listitem>
1981     </varlistentry>
1982    
1983     <varlistentry>
1984     <term>dBase file</term>
1985     <listitem>
1986     <para>
1987     dBase files are used to store the attributes for each layer. This
1988     is closely associated with the Shapefile format. For detailed
1989     specifications on the correct format of a dBase file used with
1990     Thuban please see the Technical Specification for the Shapefile
1991     format above.
1992     </para>
1993     </listitem>
1994     </varlistentry>
1995    
1996     <varlistentry>
1997     <term>PostGIS</term>
1998     <listitem>
1999     <para>
2000     PostGIS adds support for geographic objects to the PostgreSQL
2001     object-relational database. Different layer types (as for Shapefiles)
2002     are supported. <ulink url="http://postgis.refractions.net">PostGIS
2003     Homepage</ulink>
2004     </para>
2005     </listitem>
2006     </varlistentry>
2007    
2008     <varlistentry>
2009     <term>Raster files</term>
2010     <listitem>
2011     <para>
2012     Binding the GDAL library Thuban supports numerous raster file formats,
2013     see <ulink url="http://www.remotesensing.org/gdal/formats_list.html">
2014     GDAL format list</ulink> for details.</para>
2015    
2016     <para>Most commonly used is the <emphasis>TIFF/GeoTIFF</emphasis>
2017     format: Raster maps are provided as TIFF images, with an additional
2018     "world file" storing the geographic reference (usually with an
2019     extension ".tfw").
2020     </para>
2021     </listitem>
2022     </varlistentry>
2023    
2024     </variablelist>
2025     </appendix>
2026    
2027     <appendix><title>Working with PostGIS</title>
2028     <para>
2029     This section focusses on the use of PostGIS in the Thuban framework. For
2030     installation and maintenance of spatial databases we refer to the
2031     <ulink url="http://postgis.refractions.net">PostGIS Homepage</ulink>.
2032     The Thuban PostGIS support requires the
2033     <ulink url="http://initd.org/software/psycopg">psycopg module</ulink>.
2034     </para>
2035    
2036     <para>
2037     Working with PostGIS Databases is seperated into two steps:
2038     <itemizedlist>
2039     <listitem><para>Opening a Database Connection</para></listitem>
2040     <listitem><para>Loading a Data Layer</para></listitem>
2041     </itemizedlist>
2042     </para>
2043     <section><title>Opening a Database Connection</title>
2044     <para>
2045     Before a data layer can be loaded from a PostGIS database a
2046     connection with the database has to be established.
2047     <menuchoice>
2048     <guimenu>Session</guimenu>
2049     <guimenuitem>Database Connections ...</guimenuitem>
2050     </menuchoice> opens a dialog for database connection
2051     management. In the dialog new connections can be added
2052     and existing ones can be removed. Removing a database
2053     connection is not possible if the map still displays a
2054     layer provided by this database connection.
2055     </para>
2056     <figure>
2057     <title>Database Management Dialog</title>
2058     <mediaobject>
2059     <imageobject><imagedata fileref="../images/app_postgis_db_management.png" format="PNG" scale="&imgscale;"/></imageobject>
2060     <imageobject><imagedata fileref="./images/app_postgis_db_management.eps" format="EPS" scale="&imgscale;"/></imageobject>
2061     </mediaobject>
2062     </figure>
2063    
2064     <para>
2065     To add a new database connection to the session a dialog is
2066     opened to specify the relevant connection data. Enter all
2067     data relevant for your connection. If the connection fails
2068     the dialog remains open and provides some hints on the failure.
2069     </para>
2070     <figure>
2071     <title>Add Database Dialog</title>
2072     <mediaobject>
2073     <imageobject><imagedata fileref="../images/app_postgis_db_add.png" format="PNG" scale="&imgscale;"/></imageobject>
2074     <imageobject><imagedata fileref="./images/app_postgis_db_add.eps" format="EPS" scale="&imgscale;"/></imageobject>
2075     </mediaobject>
2076     </figure>
2077    
2078     <para>
2079     It is important to note that information on database connections are
2080     also stored with the session. Passwords are NOT stored. If you load a
2081     session with database connections you are asked to enter these
2082     passwords again where required.
2083     </para>
2084    
2085     </section>
2086    
2087     <section><title>Loading a Data Layer</title>
2088     <para>
2089     Data layers as part of a map are loaded with the
2090     <menuchoice>
2091     <guimenu>Map</guimenu>
2092     <guimenuitem>Add Database Layer ...</guimenuitem>
2093     </menuchoice> menu item. A dialog is raised displaying two choice
2094     lists. In the left list all connected databases are shown.
2095     Highlighting
2096     one of these and issuing a retrieval results in a list of available
2097     layer tables from that database. After selection of a
2098     layer the dialog is closed.
2099     </para>
2100     <figure>
2101     <title>Add Database Dialog</title>
2102     <mediaobject>
2103     <imageobject><imagedata fileref="../images/app_postgis_add_layer.png" format="PNG" scale="&imgscale;"/></imageobject>
2104     <imageobject><imagedata fileref="./images/app_postgis_add_layer.eps" format="EPS" scale="&imgscale;"/></imageobject>
2105     </mediaobject>
2106     </figure>
2107    
2108     </section>
2109    
2110     </appendix>
2111    
2112     <appendix><title>Supported Projections</title>
2113     <para>
2114     The following types of projections are directly support by
2115     Thuban. The specific values for each are provided by the user
2116     to create custom projections. Thuban comes with predefined
2117     projections which are available through the Projections dialog.
2118     </para>
2119     <itemizedlist>
2120     <listitem>
2121     <para>Geographic</para>
2122     <itemizedlist>
2123     <listitem><para><literal>Ellipsoid</literal></para></listitem>
2124     <listitem><para>
2125     <literal>Source Data</literal>: either Degrees or Radians
2126     </para></listitem>
2127     </itemizedlist>
2128     </listitem>
2129     <listitem>
2130     <para>Lambert Conic Conformal</para>
2131     <itemizedlist>
2132     <listitem><para><literal>Ellipsoid</literal></para></listitem>
2133     <listitem><para><literal>Latitude of 1st standard parallel</literal></para></listitem>
2134     <listitem><para><literal>Latitude of 2nd standard parallel</literal></para></listitem>
2135     <listitem><para><literal>Central Meridian</literal></para></listitem>
2136     <listitem><para><literal>Latitude of Origin</literal></para></listitem>
2137     <listitem><para><literal>False Easting</literal> (meters)</para></listitem>
2138     <listitem><para><literal>False Northing</literal> (meters)</para></listitem>
2139     </itemizedlist>
2140     </listitem>
2141     <listitem>
2142     <para>Transverse Mercator</para>
2143     <itemizedlist>
2144     <listitem><para><literal>Ellipsoid</literal></para></listitem>
2145     <listitem><para><literal>Latitude</literal>of origin</para></listitem>
2146     <listitem><para><literal>Longitude</literal>at central meridian</para></listitem>
2147     <listitem><para><literal>Scale Factor</literal>at central meridian</para></listitem>
2148     <listitem><para><literal>False Easting</literal> (meters)</para></listitem>
2149     <listitem><para><literal>False Northing</literal> (meters)</para></listitem>
2150     </itemizedlist>
2151     </listitem>
2152     <listitem>
2153     <para>Universal Transverse Mercator</para>
2154     <itemizedlist>
2155     <listitem><para><literal>Ellipsoid</literal></para></listitem>
2156     <listitem><para><literal>Zone</literal>
2157     (can be guessed appling the Propose button)</para></listitem>
2158     <listitem><para><literal>Southern Hemisphere</literal> flag</para></listitem>
2159     </itemizedlist>
2160     </listitem>
2161     </itemizedlist>
2162    
2163     <para>
2164     Thuban comes with a sample set of map projections for various
2165     European countries. Apart from the basic projection they differ
2166     especially in their parameterization:
2167     </para>
2168     <itemizedlist>
2169     <listitem><para>Belgium Datum 1972 (Lambert Conic Conformal)</para>
2170     </listitem>
2171    
2172     <listitem><para>Gauss-Boaga Zone 1 (Italy, Transverse Mercartor)</para>
2173     </listitem>
2174    
2175     <listitem><para>Gauss-Krueger Zone 2 (Germany, Transverse Mercartor)
2176     </para>
2177     </listitem>
2178    
2179     <listitem><para>Reseau Geodesique Francaise
2180     (France, Lambert Conic Conformal)</para>
2181     </listitem>
2182    
2183     <listitem><para>UK National Grid (United Kingdom, Transverse Mercartor)
2184     </para>
2185     </listitem>
2186     </itemizedlist>
2187    
2188     <para>
2189     Thuban uses the comprehensive PROJ library for projections. PROJ provides
2190     more than the four commonly used projections described above. If needed
2191     Thuban can be easily extended to a new projection covered by PROJ.
2192     </para>
2193     </appendix>
2194    
2195     </book>
2196    

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