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revision 1423 by jan, Wed Jul 16 09:52:30 2003 UTC revision 1510 by jonathan, Tue Jul 29 14:48:41 2003 UTC
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1  <?xml version="1.0" encoding="ISO-8859-1"?>  <?xml version="1.0" encoding="ISO-8859-1"?>
2  <!DOCTYPE book  <!DOCTYPE book
3          PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"          PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
4          "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">          "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
5        [<!ENTITY imgscale "70">]>
6  <!-- $Revision$ -->  <!-- $Revision$ -->
7  <book>  <book>
8    <bookinfo>    <bookinfo>
# Line 12  Line 13 
13      <author>      <author>
14        <firstname>Jan-Oliver</firstname><surname>Wagner</surname>        <firstname>Jan-Oliver</firstname><surname>Wagner</surname>
15      </author>      </author>
16        <author>
17          <firstname>Frank</firstname><surname>Koormann</surname>
18        </author>
19      <copyright>      <copyright>
20        <year>2003</year>        <year>2003</year>
21        <holder>Intevation GmbH</holder>        <holder>Intevation GmbH</holder>
# Line 20  Line 24 
24    
25    <chapter><title>Introduction</title>    <chapter><title>Introduction</title>
26      <para>      <para>
27        Thuban is a Free Software Geographic Information Systems (GIS) viewer.
28        It is being developed because there is currently no simple interactive
29        viewer for geographic information available as Free Software. Thuban is
30        written in Python and C++ and uses the wxWindows library allowing it to
31        run on many different platforms, including GNU/Linux and Windows.
32        </para>
33        <para>
34        GIS viewers are a necessary tool as they allow one to get a visual
35        impression of the positional relationship of the information that may not
36        be apparent from simple inspection of the data values themselves.
37        Thuban allows the user to create a session that displays
38        geographic data and then explore that data through navigation and
39        manipulation of how it is drawn. The results can then be saved or printed.
40        </para>
41        <para>
42        Thuban arranges a session in a hierarchy. A session contains a map which
43        consists of layers. Each layer represents one kind of data set. For
44        instance, there may be a layer for roads and another layer for buildings.
45        These layers can either be vector shapes or images.
46      </para>      </para>
47    
48          <section><title>Installation</title>          <section><title>Installation</title>
49          <para>          <para>
50          </para>          Thuban is actively supported under Debian Testing (sarge), RedHat 7.2,
51            and Windows 2000. The following list of files that Thuban requires
52            can be found on the
53            <ulink url="http://thuban.intevation.org/download.html">
54            Thuban Download site
55            </ulink>.
56            <variablelist>
57            <varlistentry>
58            <term>Debian Testing (sarge)</term>
59            <listitem>
60                <para>Thuban-0.8.1-1-debian.i386.rpm</para>
61                <para>GTK 1.2.3</para>
62                <para>Python 2.2.1</para>
63                <para>Python 2.2 XML Base Tools</para>
64                <para>wxWindows 2.4</para>
65                <para>wxWindows 2.4 Python Bindings</para>
66                <para>proj 4.4.5 Projection Library</para>
67                <para>SQLite Python Bindings 0.4.3</para>
68                <para>GDAL 1.1.8</para>
69            </listitem>
70            </varlistentry>
71            <varlistentry>
72            <term>RedHat 7.2</term>
73            <listitem>
74                <para>Thuban-0.8.1-1.i386.rpm</para>
75                <para>Python 2.2.1</para>
76                <para>wxPython 2.4 for Python 2.2 with wxGTK</para>
77                <para>proj 4.4.5 Projection Library</para>
78                <para>SQLite 2.8.3</para>
79                <para>PySQLite 0.4.3</para>
80                <para>GDAL 1.1.8</para>
81            </listitem>
82            </varlistentry>
83            <varlistentry>
84            <term>Windows 2000</term>
85            <listitem>
86                <para>Thuban-0.8.1-0.exe</para>
87                <para>Python 2.2.1</para>
88                <para>wxWindows 2.4 for Python 2.2</para>
89                <para>SQLite Python Libraries</para>
90                <para>GDAL for Thuban</para>
91            </listitem>
92            </varlistentry>
93            </variablelist>
94            </para>
95          </section>          </section>
96    
97          <section><title>The main window</title>          <section><title>The Main Window</title>
98          <para>          <para>
99                  map, legend window (dockable), Statusbat, toolbar,          <screenshot>
100                  other general stuff          <screeninfo>The Main Window</screeninfo>
101          </para>          <mediaobject>
102            <imageobject> <imagedata fileref="../images/1_2_mainwindow.png" format="PNG" scale="&imgscale;"/> </imageobject>
103            <imageobject> <imagedata fileref="./images/1_2_mainwindow.ps" format="EPS" scale="&imgscale;"/> </imageobject>
104            <textobject><phrase>The Main Window</phrase></textobject>
105            <caption><para>The Main Window</para></caption>
106            </mediaobject>
107            </screenshot>
108            </para>
109    
110            <para>
111            The map window shows the current state of the map and is where
112            the user can interact with the map using the tools.
113            </para>
114    
115            <para>
116            The legend on the left displays a list of the current layers and
117            any visible classification groups. In the example, each shape layer
118            has a default classification which specifies how the shapes in each
119            layer are drawn. Layers that are higher in the list appear
120            ``closer'' to the user. The legend can be closed by clicking on the
121            small X in the upper right-hand region of the legend.
122            To open it again, use
123            <menuchoice>
124            <guimenu>Map</guimenu>
125            <guimenuitem>Legend</guimenuitem>
126            </menuchoice>.
127            The legend is also dockable, which means that it can be detached
128            from the main window by clicking on the small button next to the
129            close button. It can be attached by clicking the same button
130            again.
131            </para>
132            <para>
133            The status bar displays different information depending on the
134            current context. If the user is selecting an item from the menu
135            then the status bar will display a short help message indicating
136            what each menu item is for. If the user has a tool selected then
137            the position of the cursor on the map is displayed.
138            </para>
139            <para>
140            The tool bar provides quick access to the commonly needed tools.
141            By hovering over each button the user can see a short messages
142            describing what the tool does. The tools provided are Zoom In, Zoom
143            Out, Pan, Full Extent, Full Layer Extent, Full Shape Extent, Identify,
144            and Label. Each of the tools will be explained in further detail later
145            in the manual.
146            </para>
147          </section>          </section>
148    
149    </chapter>    </chapter>
150    
151    <chapter><title>Session Management</title>    <chapter><title>Session Management</title>
     <para>  
     </para>  
152    
153          <section><title>Starting a new session</title>          <section><title>Starting a New Session</title>
154          <para>          <para>
155            A new session can be started from
156            <menuchoice>
157            <guimenu>File</guimenu>
158            <guimenuitem>New Session</guimenuitem>
159            </menuchoice>.
160            If a session is already loaded and has been modified without
161            being saved a prompt will ask if the current session should
162            be saved. A new session consists of an empty map with no
163            layers and no tables.
164          </para>          </para>
165          </section>          </section>
166    
167          <section><title>Opening a session</title>          <section><title>Opening a Session</title>
168          <para>          <para>
169            A session can be opened from
170            <menuchoice>
171            <guimenu>File</guimenu>
172            <guimenuitem>Open Session</guimenuitem>
173            </menuchoice>. A dialog box will open allowing the user to browse
174            for a Thuban Session file. Thuban session files end with
175            <varname>.thuban</varname>. Selecting a file a clicking
176            <guibutton>OK</guibutton> will load the session into Thuban.
177    
178            If a session is already loaded and has been modified without
179            being saved a prompt will ask if the current session should
180            be saved.
181          </para>          </para>
182          </section>          </section>
183    
184          <section><title>Saving a session</title>          <section><title>Saving a Session</title>
185          <para>          <para>
186            A session can be saved from
187            <menuchoice>
188            <guimenu>File</guimenu>
189            <guimenuitem>Save Session</guimenuitem>
190            </menuchoice>. A dialog box will open allowing the user to browse
191            the file system and select a place to save the session. Thuban
192            sessions should be saved under a name ending in
193            <varname>.thuban</varname>. If the file already exists the user
194            will be prompted to save under a different name or overwrite the
195            existing file.
196          </para>          </para>
197          </section>          </section>
198    
199          <section><title>The session info-tree</title>          <section><title>The Session Info-Tree</title>
200            <para>
201            <screenshot>
202            <screeninfo>Session Info Tree</screeninfo>
203            <mediaobject>
204            <imageobject><imagedata fileref="../images/2_4_session_tree.png" format="PNG" scale="&imgscale;"/></imageobject>
205            <imageobject><imagedata fileref="./images/2_4_session_tree.eps" format="EPS" scale="&imgscale;"/></imageobject>
206            <textobject><phrase>Session Info Tree</phrase></textobject>
207            <caption><para>Session Info Tree</para></caption>
208            </mediaobject>
209            </screenshot>
210            </para>
211          <para>          <para>
212                  (primarily for developers)          The session info-tree is primarily intended for developers working
213            with Thuban. It displays many of the internal values for the session,
214            map, and layers. It can be opened from
215            <menuchoice>
216            <guimenu>File</guimenu>
217            <guimenuitem>Session Tree</guimenuitem>
218            </menuchoice>.
219          </para>          </para>
220          </section>          </section>
221    </chapter>    </chapter>
222    
223    <chapter><title>Map Management</title>    <chapter><title>Map Management</title>
224      <para>      <para>
225        The map consists of a number of layers where each layer represents a
226        different type of data set. By interacting with the map the user can
227        visually explore the data.
228        </para>
229        <para>
230        The map can have a name that will appear in the Thuban title bar.
231        The map name can be changed using
232        <menuchoice>
233        <guimenu>Map</guimenu>
234        <guimenuitem>Rename</guimenuitem>
235        </menuchoice>.
236        </para>
237        <para>
238        <inlinemediaobject>
239        <imageobject>
240        <imagedata fileref="../images/3_rename_map.png" format="PNG" scale="&imgscale;"/>
241        </imageobject>
242        <imageobject>
243        <imagedata fileref="./images/3_rename_map.eps" format="EPS" scale="&imgscale;"/>
244        </imageobject>
245        <textobject> <phrase>Rename Map</phrase> </textobject>
246        </inlinemediaobject>
247      </para>      </para>
248    
249          <section><title>Adding and removing layers</title>          <section><title>Adding and Removing Layers</title>
250            <para>
251            There are two types of layers that can be added to a map: shape layers
252            and image layers. Shape layers are stored in Shapefile format, a
253            standard file format for storing geographic objects. These
254            files have the extension ``.shp''. Associated with
255            the shape file is a database file which stores attributes for
256            each shape in the shape file. This file, in dBase format,
257            has the extension ``.dbf''. Both files must have the same base name.
258            For example, if there is a shape file named roads.shp there must
259            also be a file roads.dbf.
260            </para>
261            <para>
262            Shape layers can be added to the map with
263            <menuchoice>
264            <guimenu>Map</guimenu>
265            <guimenuitem>Add Layer</guimenuitem>
266            </menuchoice>.
267            Thuban will load all files with the same base name, so it doesn't
268            matter if the shape file or database file is selected.
269            </para>
270    
271          <para>          <para>
272            Image layers can be added to the map with
273            <menuchoice>
274            <guimenu>Map</guimenu>
275            <guimenuitem>Add Image Layer</guimenuitem>
276            </menuchoice>.
277            It is important to select a valid image file that has geographic
278            data associated with it. The data can be embedded in the file itself,
279            or in another file. If geographic information cannot be found, Thuban
280            will report an error.
281          </para>          </para>
282          </section>          </section>
283    
284          <section><title>Navigation</title>          <section><title>Navigation</title>
285          <para>          <para>
286            The map can be explored by using the navigation tools available on
287            the tool bar or from the
288            <menuchoice><guimenu>Map</guimenu></menuchoice> menu.
289            </para>
290            <para>
291            The ZoomIn tool
292            <inlinemediaobject>
293            <imageobject>
294            <imagedata fileref="../images/3_2_zoomin.png" format="PNG" scale="&imgscale;"/>
295            </imageobject>
296            <imageobject>
297            <imagedata fileref="./images/3_2_zoomin.eps" format="EPS" scale="&imgscale;"/>
298            </imageobject>
299            <textobject> <phrase>ZoomIn Tool</phrase> </textobject>
300            </inlinemediaobject>
301            enlarges a region of the map. Clicking once on the map
302            will double the magnification and center the map on the point that
303            was clicked. Clicking and dragging selects a region that will be
304            enlarged to fit the window.
305            </para>
306            <para>
307            The ZoomOut tool
308            <inlinemediaobject>
309            <imageobject>
310            <imagedata fileref="../images/3_2_zoomout.png" format="PNG" scale="&imgscale;"/>
311            </imageobject>
312            <imageobject>
313            <imagedata fileref="./images/3_2_zoomout.eps" format="EPS" scale="&imgscale;"/>
314            </imageobject>
315            <textobject> <phrase>ZoomOut Tool</phrase> </textobject>
316            </inlinemediaobject>
317            shrinks the map so that a larger region is visible. A single click
318            reduces the magnification by a factor of two. Clicking and dragging
319            selects a box such that the current contents of the window will be
320            scaled to fit into that box.
321            </para>
322            <para>
323            The Pan tool
324            <inlinemediaobject>
325            <imageobject>
326            <imagedata fileref="../images/3_2_pan.png" format="PNG" scale="&imgscale;"/>
327            </imageobject>
328            <imageobject>
329            <imagedata fileref="./images/3_2_pan.eps" format="EPS" scale="&imgscale;"/>
330            </imageobject>
331            <textobject> <phrase>Pan Tool</phrase> </textobject>
332            </inlinemediaobject>
333            allows the user to move the map around by clicking and dragging.
334            </para>
335            <para>
336            The Full Extent tool
337            <inlinemediaobject>
338            <imageobject>
339            <imagedata fileref="../images/3_2_fullextent.png" format="PNG" scale="&imgscale;"/>
340            </imageobject>
341            <imageobject>
342            <imagedata fileref="./images/3_2_fullextent.eps" format="EPS" scale="&imgscale;"/>
343            </imageobject>
344            <textobject> <phrase>Full Extent Tool</phrase> </textobject>
345            </inlinemediaobject>
346            rescales the viewable region so that the entire map is visible.
347            </para>
348            <para>
349            The Full Layer Extent tool
350            <inlinemediaobject>
351            <imageobject>
352            <imagedata fileref="../images/3_2_fulllayerextent.png" format="PNG" scale="&imgscale;"/>
353            </imageobject>
354            <imageobject>
355            <imagedata fileref="./images/3_2_fulllayerextent.eps" format="EPS" scale="&imgscale;"/>
356            </imageobject>
357            <textobject> <phrase>Full Layer Extent Tool</phrase> </textobject>
358            </inlinemediaobject>
359            rescales the viewable region so that the currently selected
360            layer fits within the window. If no layer is selected this button
361            will be disabled.
362            </para>
363            <para>
364            The Full Shape Extent tool
365            <inlinemediaobject>
366            <imageobject>
367            <imagedata fileref="../images/3_2_fullshapeextent.png" format="PNG" scale="&imgscale;"/>
368            </imageobject>
369            <imageobject>
370            <imagedata fileref="./images/3_2_fullshapeextent.eps" format="EPS" scale="&imgscale;"/>
371            </imageobject>
372            <textobject> <phrase>Full Shape Extent Tool</phrase> </textobject>
373            </inlinemediaobject>
374            rescales the viewable region so that the currently selected
375            shape fits within the window. If the shape is a point, it is
376            centered and the map is zoomed all the way in. If no shape is
377            selected this button will be disabled. This feature is especially
378            helpful when identifying an object related to a selected record
379            in a tableview (see below).
380    
381          </para>          </para>
382          </section>          </section>
383    
384          <section><title>Object identification</title>          <section><title>Object Identification</title>
385          <para>          <para>
386            Objects on the map can be identified using the Identify tool
387            <inlinemediaobject>
388            <imageobject>
389            <imagedata fileref="../images/3_3_identify.png" format="PNG" scale="&imgscale;"/>
390            </imageobject>
391            <imageobject>
392            <imagedata fileref="./images/3_3_identify.eps" format="EPS" scale="&imgscale;"/>
393            </imageobject>
394            <textobject> <phrase>Identify Tool</phrase> </textobject>
395            </inlinemediaobject>.
396            Clicking on an object selects that object and opens a dialog which
397            shows all the table attributes for that object. Any current selection
398            is lost. Objects on the map are typically shapes and this document
399            will often refer to objects as shapes.
400          </para>          </para>
401          </section>          </section>
402    
403          <section><title>Object labelling</title>          <section><title>Object Labeling</title>
404          <para>          <para>
405            Objects can be labeled using the Label tool
406            <inlinemediaobject>
407            <imageobject>
408            <imagedata fileref="../images/3_3_label.png" format="PNG" scale="&imgscale;"/>
409            </imageobject>
410            <imageobject>
411            <imagedata fileref="./images/3_3_label.eps" format="EPS" scale="&imgscale;"/>
412            </imageobject>
413            <textobject> <phrase>Label Tool</phrase> </textobject>
414            </inlinemediaobject>.
415            Clicking on an object selects that object and opens a dialog which
416            displays the table attributes for that object. An attribute can
417            be selected to be the label on the map. The label will be placed
418            at the center of the shape. Clicking on an object that already has
419            a label will remove the label.
420          </para>          </para>
421          </section>          </section>
422    
423          <section><title>The legend</title>          <section><title>The Legend</title>
424            <para>
425            <inlinemediaobject>
426            <imageobject>
427            <imagedata fileref="../images/3_5_legend.png" format="PNG" scale="&imgscale;"/>
428            </imageobject>
429            <imageobject>
430            <imagedata fileref="./images/3_5_legend.eps" format="EPS" scale="&imgscale;"/>
431            </imageobject>
432            <textobject> <phrase>Legend</phrase> </textobject>
433            </inlinemediaobject>
434            </para>
435          <para>          <para>
436            The Legend provides an overview of the layers in the map. Layers
437            that appear higher in the legend will appear ``closer'' to the user.
438            If a layer supports classification (currently, only shape layers
439            have this feature) then the classification groups will be shown
440            below each layer. The properties for each group are also displayed
441            with a small graphic. Polygon layers appear as rectangles, lines
442            appear as curved lines, and points appear as circles.
443            </para>
444            <para>
445            Along the top of the legend is a toolbar which allows quick access
446            to some of the layer manipulation options under
447            <menuchoice><guimenu>Map</guimenu></menuchoice>.
448            </para>
449    
450            <para>
451            The Move Layer to Top tool
452            <inlinemediaobject>
453            <imageobject>
454            <imagedata fileref="../images/3_5_totop.png" format="PNG" scale="&imgscale;"/>
455            </imageobject>
456            <imageobject>
457            <imagedata fileref="./images/3_5_totop.eps" format="EPS" scale="&imgscale;"/>
458            </imageobject>
459            <textobject> <phrase>Move Layer to Top</phrase> </textobject>
460            </inlinemediaobject> raises the selected layer to the top of the map.
461            </para>
462    
463            <para>
464            The Move Layer Up tool
465            <inlinemediaobject>
466            <imageobject>
467            <imagedata fileref="../images/3_5_moveup.png" format="PNG" scale="&imgscale;"/>
468            </imageobject>
469            <imageobject>
470            <imagedata fileref="./images/3_5_moveup.eps" format="EPS" scale="&imgscale;"/>
471            </imageobject>
472            <textobject> <phrase>Move Layer Up</phrase> </textobject>
473            </inlinemediaobject> raises the selected layer one level.
474            </para>
475    
476            <para>
477            The Move Layer Down tool
478            <inlinemediaobject>
479            <imageobject>
480            <imagedata fileref="../images/3_5_movedown.png" format="PNG" scale="&imgscale;"/>
481            </imageobject>
482            <imageobject>
483            <imagedata fileref="./images/3_5_movedown.eps" format="EPS" scale="&imgscale;"/>
484            </imageobject>
485            <textobject> <phrase>Move Layer Down</phrase> </textobject>
486            </inlinemediaobject> lowers the selected layer one level.
487            </para>
488    
489            <para>
490            The Move Layer to Bottom tool
491            <inlinemediaobject>
492            <imageobject>
493            <imagedata fileref="../images/3_5_tobottom.png" format="PNG" scale="&imgscale;"/>
494            </imageobject>
495            <imageobject>
496            <imagedata fileref="./images/3_5_tobottom.eps" format="EPS" scale="&imgscale;"/>
497            </imageobject>
498            <textobject> <phrase>Move Layer to Bottom</phrase> </textobject>
499            </inlinemediaobject> lowers the selected layer to the bottom of the map.
500            </para>
501    
502            <para>
503            The Visible tool
504            <inlinemediaobject>
505            <imageobject>
506            <imagedata fileref="../images/3_5_visible.png" format="PNG" scale="&imgscale;"/>
507            </imageobject>
508            <imageobject>
509            <imagedata fileref="./images/3_5_visible.eps" format="EPS" scale="&imgscale;"/>
510            </imageobject>
511            <textobject> <phrase>Visible</phrase> </textobject>
512            </inlinemediaobject> shows the selected layer in the map if it was
513            hidden.
514            </para>
515    
516            <para>
517            The Invisible tool
518            <inlinemediaobject>
519            <imageobject>
520            <imagedata fileref="../images/3_5_invisible.png" format="PNG" scale="&imgscale;"/>
521            </imageobject>
522            <imageobject>
523            <imagedata fileref="./images/3_5_invisible.eps" format="EPS" scale="&imgscale;"/>
524            </imageobject>
525            <textobject> <phrase>Invisible</phrase> </textobject>
526            </inlinemediaobject> hides the selected layer in the map.
527            </para>
528    
529            <para>
530            The Properties tool
531            <inlinemediaobject>
532            <imageobject>
533            <imagedata fileref="../images/3_5_props.png" format="PNG" scale="&imgscale;"/>
534            </imageobject>
535            <imageobject>
536            <imagedata fileref="./images/3_5_props.eps" format="EPS" scale="&imgscale;"/>
537            </imageobject>
538            <textobject> <phrase>Properties</phrase> </textobject>
539            </inlinemediaobject> opens the layer's properties dialog box.
540            Double-clicking on a layer or a group of a layer will open the
541            properties dialog for that layer.
542          </para>          </para>
543    
544            <para>
545            Along the bottom of the legend is the scalebar. The scalebar
546            will be available if there are any layers and the  map has a
547            projection set.
548            </para>
549            </section>
550    
551            <section><title>Exporting</title>
552            <para>
553            Under Windows, maps can be exported in Enhanced Metafile format
554            (<varname>.wmf</varname>)
555            from
556            <menuchoice>
557            <guimenu>Map</guimenu>
558            <guimenuitem>Export</guimenuitem>
559            </menuchoice> for use in reports, presentations, or further
560            modification. The current map view, legend, and, if available,
561            scalebar are exported. Under other platforms this option is not
562            available. Clicking this menu item open a file selection dialog
563            that lets the user select a location to export the map.
564            </para>
565          </section>          </section>
566    
567          <section><title>Printing</title>          <section><title>Printing</title>
568          <para>          <para>
569            The map can be printed using
570            <menuchoice>
571            <guimenu>Map</guimenu>
572            <guimenuitem>Print</guimenuitem>
573            </menuchoice>. The current map view, legend, and, if available,
574            scalebar are printed. A standard printing dialog will open allowing
575            the user to configure the printer. This dialog will differ depending
576            on which platform Thuban is running.
577          </para>          </para>
578          </section>          </section>
579    
580    </chapter>    </chapter>
581    
582    <chapter><title>Layer Management</title>    <chapter><title>Layer Management</title>
583      <para>      <para>
584      </para>      </para>
585    
586          <section><title>Layer types</title>          <section><title>Types of Layers</title>
587          <para>          <para>
588            There are two types of layers supported by Thuban: shape layers and
589            image layers. Shape layers consist of vector based shapes with
590            geo-referenced coordinates. There are three types of supported
591            shapes: polygons, lines (arc), and points. Image layers can be any image
592            file format supported by the Geo-spatial Data Abstraction Library
593            (GDAL). The images must have geographic
594            coordinate data either embedded within the file or in a separate
595            file that is in the same directory as the image file. GeoTIFF files
596            work very well with Thuban and were designed specifically to be image
597            layers in GIS programs.
598          </para>          </para>
599            <para>
600            All actions in the
601            <menuchoice>
602            <guimenu>Layer</guimenu>
603            </menuchoice> menu act on the currently selected layer in the legend.
604            </para>
605          </section>          </section>
606    
607          <section><title>Visibility</title>          <section><title>Properties</title>
608          <para>          <para>
609            To view the properties for a layer it must first be selected in the
610            legend. The menu option
611            <menuchoice>
612            <guimenu>Layer</guimenu>
613            <guimenuitem>Properties</guimenuitem>
614            </menuchoice> opens a dialog that displays a layer's properties.
615            All layers have a title which can be modified in the text field
616            provided. The type of layer is also shows. If the type is a type
617            of shape (polygon, arc, point) the classification table will be
618            shown. Image layers have no other properties other than title
619            and type.
620            </para>
621            <para>
622            <screenshot>
623            <screeninfo>Properties Window</screeninfo>
624            <mediaobject>
625            <imageobject><imagedata fileref="../images/4_2_layer_properties.png" format="PNG" scale="&imgscale;"/></imageobject>
626            <imageobject><imagedata fileref="./images/4_2_layer_properties.eps" format="EPS" scale="&imgscale;"/></imageobject>
627            <textobject><phrase>Properties Window</phrase></textobject>
628            <caption><para>The Properties Window for a Shape Layer</para></caption>
629            </mediaobject>
630            </screenshot>
631            </para>
632            <para>
633            <screenshot>
634            <screeninfo>Properties Window</screeninfo>
635            <mediaobject>
636            <imageobject><imagedata fileref="../images/4_2_raster_layer_properties.png" format="PNG" scale="&imgscale;"/></imageobject>
637            <imageobject><imagedata fileref="./images/4_2_raster_layer_properties.eps" format="EPS" scale="&imgscale;"/></imageobject>
638            <textobject><phrase>Properties Window</phrase></textobject>
639            <caption><para>The Properties Window for an Image Layer</para></caption>
640            </mediaobject>
641            </screenshot>
642          </para>          </para>
643          </section>          </section>
644    
645          <section><title>Sequence</title>          <section><title>Visibility</title>
646          <para>          <para>
647            Sometimes it is not desirable to view all layers at the same time.
648            Some layers may take a long time to draw and so while navigating
649            around the map the user may not want to wait for the map to redraw
650            all the layers each time the map is changed. Each layer can be
651            independently turned on or off using the
652            <menuchoice>
653            <guimenu>Layer</guimenu>
654            <guimenuitem>Show</guimenuitem>
655            </menuchoice>
656            or
657            <menuchoice>
658            <guimenu>Layer</guimenu>
659            <guimenuitem>Hide</guimenuitem>
660            </menuchoice> options respectively.
661          </para>          </para>
662          </section>          </section>
663    
664          <section><title>Duplication</title>          <section><title>Duplication</title>
665          <para>          <para>
666            Layers and all their properties, including classifications, can
667            be duplicated using
668            <menuchoice>
669            <guimenu>Layer</guimenu>
670            <guimenuitem>Duplicate</guimenuitem>
671            </menuchoice>. Duplicating a layer is useful if the user wishes
672            to model a layer in several different ways. Even though the layers
673            overlap, by carefully selecting the shape properties it is possible
674            to display several pieces of information at once. For example, one
675            copy of a roads layer may be classified on a length property and
676            another copy may be classified on a type property. If the length
677            property was expressed with color and the type property expressed
678            with line thickness then it would be possible to view both
679            classifications by placing the type property copy over the
680            length property copy.
681          </para>          </para>
682          </section>          </section>
683    
         <section><title>Properties</title>  
         <para>  
         </para>  
         </section>  
684    </chapter>    </chapter>
685    
686    <chapter><title>Layer Classifications</title>    <chapter><title>Layer Classifications</title>
687      <para>      <para>
688        A layer classification is a way of assigning drawing properties to
689        groups of shapes based on attributes stored in the layer's table.
690        Only layer's with shapes can have a classification; image layers
691        cannot be classified.
692        </para>
693        <para>
694        A classification consists of a number of groups, each group
695        having a value or range of values to match against, and symbol
696        properties which control how a shape is drawn on the map. The user
697        selects which field in the table is used by the classification and
698        when the map is drawn the value for that field for each shape is
699        compared with each group's value. The properties of the first group
700        to match are used to draw the shape. This allows the user to get a
701        visual impression of not only how the data is laid out but also what
702        kind of data lies where.
703        </para>
704        <para>
705        A layer always has a classification. When a new layer is added to the
706        map, a default classification is created with the DEFAULT group. This
707        group cannot be removed but can be hidden (see below). Every shape in the
708        layer, regardless of its attributes, will match this group if no other
709        group matches.
710      </para>      </para>
711    
712          <section><title>Adding and removing classes</title>          <section><title>Editing Classifications</title>
713          <para>          <para>
714            A layer's classification can be modified under the properties dialog
715            (<menuchoice>
716            <guimenu>Layer</guimenu>
717            <guimenuitem>Properties</guimenuitem>
718            </menuchoice>). The layer's classification field can be set to None,
719            which simply assigns a DEFAULT group to the classification. No new
720            groups can be added to the classification if the field is None.
721            The user must first select a field to classify on. New groups can
722            be added to the classification with the <guibutton>Add</guibutton>
723            button.
724            </para>
725            <para>
726            To apply the changes to the map the user can click
727            either <guibutton>Try</guibutton> or <guibutton>OK</guibutton>.
728            <guibutton>Try</guibutton> will not close the dialog box, allowing
729            the user to see how the classification changes the map.
730            <guibutton>Revert</guibutton> will undo the last classification applied
731            to the map. <guibutton>OK</guibutton> will commit the changes and
732            close the dialog. The user will be unable to undo the changes.
733            <guibutton>Close</guibutton> simply closes the dialog box. If any
734            changes have not been applied with <guibutton>Try</guibutton> the
735            changes will not be applied to the map.
736            </para>
737            <para>
738            <screenshot>
739            <screeninfo>Properties Window</screeninfo>
740            <mediaobject>
741            <imageobject><imagedata fileref="../images/5_classification.png" format="PNG" scale="&imgscale;"/></imageobject>
742            <imageobject><imagedata fileref="./images/5_classification.eps" format="EPS" scale="&imgscale;"/></imageobject>
743            <textobject><phrase>Properties Window</phrase></textobject>
744            <caption><para>The Properties Window with Classifications</para></caption>
745            </mediaobject>
746            </screenshot>
747            </para>
748            <para>
749            The order of the groups in the classification is significant
750            except for the DEFAULT group, which remains at the top. When shapes
751            are matched against groups the matching begins at the first group
752            after the DEFAULT group so that groups higher in the list will
753            be checked first. Matching for a
754            given shape will stop at the first group that matches. The user can
755            use <guibutton>Move Up</guibutton> and <guibutton>Move Down</guibutton>
756            to change the order of the groups. The DEFAULT group will always
757            match a shape that hasn't matched another group.
758          </para>          </para>
759                <section><title>Visible</title>
760                <para>
761                The Visible column has check-boxes that determine whether a
762                classification group will be displayed in the legend. This is
763                useful if the user knows that the groups completely cover
764                the data set and don't want the DEFAULT group to be displayed
765                in the legend and on a printout.
766                </para>
767            </section>
768                <section><title>Symbols</title>
769                <para>
770                Each type of shape has its own type of symbol. Thuban supports three
771                types of shapes: polygons, lines, and points. Polygons and points
772                have outline and fill color, while lines have only line color. Each
773                group has associated symbol properties. To edit the symbol
774                properties for a group the user can double click on the Symbol
775                column or select a group and click the
776                <guibutton>Edit Symbol</guibutton> button.
777                </para>
778                </section>
779            <section><title>Value</title>
780                <para>
781                The Value column of the classification table is the value that will
782                be matched when the map is being drawn. The type of data that can
783                entered into this field depends on the type of data of the
784                classification field.
785                </para>
786                <para>
787                If the field is of type Text, anything entered
788                into the field is valid. The text will be compared literally to the
789                value of the shape attribute, including case sensitivity.
790                If the type is Integer, then any valid integer may be entered. In
791                addition, with special syntax, a range of values can be entered.
792                A range from <varname>start</varname> to <varname>end</varname>
793                inclusive is specified like this: <literal>[start;end]</literal>.
794                The exclusive range is specified like this:
795                <literal>]start;end[</literal>. Ranges can include infinity like
796                this: <literal>[-oo;oo]</literal>. Field types can also be of type
797                Decimal. They represent any rational number and can be used in
798                ranges as well.
799                </para>
800                </section>
801                <section><title>Label</title>
802                <para>
803                By default, the text that is displayed for a group in the legend
804                is the value for that group. The label can substitute a more
805                descriptive term in the legend.
806                </para>
807            </section>
808          </section>          </section>
809    
810          <section><title>Editing symbols</title>          <section><title>Generating Classes</title>
811          <para>          <para>
812            <screenshot>
813            <screeninfo>Generate Class</screeninfo>
814            <mediaobject>
815            <imageobject><imagedata fileref="../images/5_3_genclass.png" format="PNG" scale="&imgscale;"/></imageobject>
816            <imageobject><imagedata fileref="./images/5_3_genclass.eps" format="EPS" scale="&imgscale;"/></imageobject>
817            <textobject><phrase>Generate Class</phrase></textobject>
818            <caption><para>The Generate Classifications Dialog</para></caption>
819            </mediaobject>
820            </screenshot>
821          </para>          </para>
         </section>  
   
         <section><title>Automatic generation of classes</title>  
822          <para>          <para>
823            Creating a classification by hand can be tedious.
824            Thuban, therefore, provides a means of generating an entire
825            classification at once while still giving the user control over
826            how it appears. Clicking <guibutton>Generate Class</guibutton>
827            opens the <varname>Generate Classification</varname> dialog.
828            Under the <varname>Generate</varname> pull down there are at most
829            three different ways to generate classifications:
830            Unique Values, Uniform Distribution, and Quantiles. Some options
831            may not be available if the data type for the field does not
832            support them. For instance, <varname>Uniform Distribution</varname>
833            doesn't make sense for a Text field.
834          </para>          </para>
835            <para>
836            For every way of generating a classification, a color scheme must
837            be selected. Thuban provides several different color schemes that
838            affect how the group properties change over the classification.
839            It is also possible to create a custom color scheme. Selecting
840            this option will display two symbols: the one of the left has the
841            properties of the first group and the one on the right has the
842            properties of the last group. Thuban will interpolate between these
843            two properties to generate the other groups.
844            <screenshot>
845            <screeninfo>Custom Color Scheme</screeninfo>
846            <mediaobject>
847            <imageobject><imagedata fileref="../images/5_2_custom_ramp.png" format="PNG" scale="&imgscale;"/></imageobject>
848            <imageobject><imagedata fileref="./images/5_2_custom_ramp.eps" format="EPS" scale="&imgscale;"/></imageobject>
849            <textobject><phrase>Custom Color Scheme</phrase></textobject>
850            <caption><para>Custom Color Scheme</para></caption>
851            </mediaobject>
852            </screenshot>
853            </para>
854            <para>
855            The Unique Values option lets the user select specific values that
856            appear in the table. Clicking <guibutton>Retrieve From Table</guibutton>
857            searches the table for all unique values and displays them in the
858            list on the left. Items can be selected and moved to the list on the
859            right. Each list can be sorted or reversed for easier searching.
860            The classification that is generated will be in the same order as
861            the list on the right.
862            <screenshot>
863            <screeninfo>Unique Values</screeninfo>
864            <mediaobject>
865            <imageobject><imagedata fileref="../images/5_2_unique_values.png" format="PNG" scale="&imgscale;"/></imageobject>
866            <imageobject><imagedata fileref="./images/5_2_unique_values.eps" format="EPS" scale="&imgscale;"/></imageobject>
867            <textobject><phrase>Unique Values</phrase></textobject>
868            <caption><para>Unique Values Classification</para></caption>
869            </mediaobject>
870            </screenshot>
871            </para>
872            <para>
873            The Uniform Distribution option creates a user specified number of
874            groups of ranges such that each range covers equal intervals. The
875            minimum and maximum values can automatically be retrieved from the
876            table by clicking <guibutton>Retrieve From Table</guibutton>. The
877            stepping is how large each interval is. Adjusting this value will
878            automatically recalculate how many groups is appropriate.
879            <screenshot>
880            <screeninfo>Uniform Distribution</screeninfo>
881            <mediaobject>
882            <imageobject><imagedata fileref="../images/5_2_uniform_dist.png" format="PNG" scale="&imgscale;"/></imageobject>
883            <imageobject><imagedata fileref="./images/5_2_uniform_dist.eps" format="EPS" scale="&imgscale;"/></imageobject>
884            <textobject><phrase>Uniform Distribution</phrase></textobject>
885            <caption><para>Uniform Distribution Classification</para></caption>
886            </mediaobject>
887            </screenshot>
888            </para>
889            <para>
890            The Quantiles option generates ranges based on the number of items
891            in the table. For example, by specifying five groups Thuban will
892            generate five groups with appropriate ranges such that 20% of the table
893            data is in each group. If it is impossible to generate exact
894            groupings, Thuban will issue a warning but allow the user to continue.
895            <screenshot>
896            <screeninfo>Quantiles</screeninfo>
897            <mediaobject>
898            <imageobject><imagedata fileref="../images/5_2_quantiles.png" format="PNG" scale="&imgscale;"/></imageobject>
899            <imageobject><imagedata fileref="./images/5_2_quantiles.eps" format="EPS" scale="&imgscale;"/></imageobject>
900            <textobject><phrase>Quantiles</phrase></textobject>
901            <caption><para>Quantiles Classification</para></caption>
902            </mediaobject>
903            </screenshot>
904            </para>
905          </section>          </section>
906    </chapter>    </chapter>
907    
908    <chapter><title>Projection Management</title>    <chapter><title>Projection Management</title>
909      <para>      <para>
910        Projections control how the geographic data is displayed on the screen.
911        If multiple layers are loaded into Thuban where the geographic data
912        is in a different projection system, then the user must specify a
913        projection for each layer. The user must also tell Thuban which
914        projection the map is in. This can be the same as the layers or a different
915        projection in which case the layers are reprojected into that space.
916        The map projection can be set using
917        <menuchoice>
918        <guimenu>Map</guimenu>
919        <guimenuitem>Projection</guimenuitem>
920        </menuchoice> and the layer projection can be set using
921        <menuchoice>
922        <guimenu>Layer</guimenu>
923        <guimenuitem>Projection</guimenuitem>
924        </menuchoice>.
925        <screenshot>
926        <screeninfo>Projection Window</screeninfo>
927        <mediaobject>
928        <imageobject><imagedata fileref="../images/6_projection.png" format="PNG" scale="&imgscale;"/></imageobject>
929        <imageobject><imagedata fileref="./images/6_projection.eps" format="EPS" scale="&imgscale;"/></imageobject>
930        <textobject><phrase>Projection Window</phrase></textobject>
931        <caption><para>The Projection Window</para></caption>
932        </mediaobject>
933        </screenshot>
934      </para>      </para>
935        <para>
936        Thuban is distributed with a sample collection of projections. The
937        user can create new projections and make them available to all
938        future Thuban sessions. They may also be exported and imported so
939        that custom projections can be distributed.
940        </para>
941            <section><title>Selecting a Projection</title>
942            <para>
943            The available projections are listed on the left. If the layer
944            or map already has a projection it will initially be highlighted
945            and will end with <varname>(current)</varname>. Selecting
946            <varname>&lt;None&gt;</varname> will cause Thuban to use the data as
947            it appears in the source file and will not use a projection.
948            </para>
949        </section>
950            <section><title>Editing a Projection</title>
951            <para>
952            Whenever a projection is selected from the list its properties
953            are displayed on the right. These properties can be changed
954            and the changes saved to the selected projection using
955            <guibutton>Update</guibutton>. Only a projection that comes
956            from a file can be updated, so if the current layer's projection
957            is selected, <guibutton>Update</guibutton> will be disabled.
958            <guibutton>Add to List</guibutton> adds the projection to the
959            list of available projections as a new entry, and thus makes it
960            available to future Thuban sessions. Clicking <guibutton>New</guibutton>
961            will create an entirely new, empty projection. The
962            <guibutton>Remove</guibutton> button will permanently remove a
963            projection from the list of available projections.
964            </para>
965            <para>
966            To apply the selected projection to the map the user can click
967            either <guibutton>Try</guibutton> or <guibutton>OK</guibutton>.
968            <guibutton>Try</guibutton> will not close the dialog box, allowing
969            the user to see how the projeciton changes the map.
970            <guibutton>Revert</guibutton> will undo the last projection applied
971            to the map. <guibutton>OK</guibutton> will commit the changes and
972            close the dialog. The user will be unable to undo the changes.
973            <guibutton>Close</guibutton> simply closes the dialog box. If no
974            selection has been applied with <guibutton>Try</guibutton> the
975            selection will not be applied to the map.
976            </para>
977        </section>
978            <section><title>Importing/Exporting Projections</title>
979            <para>
980            The projections that appear in the list of available projections
981            can be exported to another file that the user chooses. By selecting
982            one or more projections and clicking <guibutton>Export</guibutton>
983            the user will be able to select a file in which to store those
984            projections.
985            The file can then be distributed to other Thuban users. To import
986            a projection file the user can click <guibutton>Import</guibutton>.
987            The imported projections are added to the list and are then available
988            to the current session and any future Thuban sessions.
989            </para>
990        </section>
991    </chapter>    </chapter>
992    
993    <chapter><title>Table Management</title>    <chapter><title>Table Management</title>
994      <para>      <para>
995        Thuban distinguishes two different types of tables: Attribute tables
996        (which belong to a layer) and normal data tables. Both provide
997            the same general functionality with the difference that actions on an
998        attribute table might also effect the map display.
999      </para>      </para>
1000    
1001        <section><title>Table View</title>
1002            <para>
1003            <screenshot>
1004            <screeninfo>Table View</screeninfo>
1005            <mediaobject>
1006            <imageobject><imagedata fileref="../images/7_1_table_view.png" format="PNG" scale="&imgscale;"/></imageobject>
1007            <imageobject><imagedata fileref="./images/7_1_table_view.eps" format="EPS" scale="&imgscale;"/></imageobject>
1008            <textobject><phrase>Table View</phrase></textobject>
1009            <caption><para>The Table View</para></caption>
1010            </mediaobject>
1011            </screenshot>
1012            </para>
1013            <para>
1014            Thuban provides a standard dialog to display table contents, the
1015            Table View. The view has five sections: The title, selections,
1016            the table grid, export functions, and the status bar.
1017            </para>
1018            <para>
1019            The title bar identifies the table with its name.
1020            </para>
1021            <para>
1022            The selections box let the user perform simple analysis on the data
1023            based on comparisons: The first choice must be a field identifier of
1024            the table, the second choice determines the type of comparison. The
1025            third choice can be either a specific value (interpreted as numerical
1026            or string depending on the type of the first field) or a second field
1027            identifier. Thus you can perform analysis like selecting all
1028            records where <literal>population > 10000</literal> or
1029            <literal>cars_per_inhabitant < bikes_per_inhabitant</literal>
1030            (note that the field names are only explanatory, the dBase files
1031            allow only 11 character field names).
1032          
1033            Selections can be combined either by applying a selection only on
1034            a previously selected set of records or by adding the results of a
1035            selection to a previous set. The default is that a selection replaces
1036            earlier results.
1037            </para>
1038            <para>
1039            The table grid shows the contents of the table (one record per row),
1040            with highlighted selection results. Columns and rows can be resized.
1041            </para>
1042            <para>
1043            The contents of a table can be exported into a file, either dBase
1044            format (DBF) or comma separated values (CSV). The
1045            <guibutton>Export</guibutton> button
1046            raises a file dialog to specify a path and file name, the export type
1047            is determined by the file extension (either .dbf or .csv).
1048    
1049            The <guibutton>Export Selection</guibutton> button works similarly
1050            but exports only the selected records.
1051    
1052            The <guibutton>Close</guibutton> button closes the table view window.
1053            This is different from the menu item
1054            <menuchoice>
1055            <guimenu>Table</guimenu>
1056            <guimenuitem>Close</guimenuitem>
1057            </menuchoice> which unloads the table from Thuban.
1058            </para>
1059            <para>
1060            The status bar displays some statistics about the table and optional
1061            selection results.
1062            </para>
1063        </section>
1064    
1065        <section><title>General Functionality (Menu Table)</title>
1066            <para>
1067            The general functions affect all tables open in Thuban. Attribute
1068            tables are considered here as normal data tables (with the exception
1069            that they cannot be closed).
1070            </para>
1071            <section><title>Open</title>
1072                <para>
1073                The
1074                <menuchoice>
1075                <guimenu>Table</guimenu>
1076                <guimenuitem>Open</guimenuitem>
1077                </menuchoice>
1078                item raises a file dialog to let you select a
1079                dBase file from the file system to be loaded into Thuban read-only.
1080                On <guibutton>OK</guibutton> the selected file is loaded and a
1081                table view is opened.
1082                </para>
1083            </section>
1084    
1085            <section><title>Close</title>
1086                <para>
1087                The
1088                <menuchoice>
1089                <guimenu>Table</guimenu>
1090                <guimenuitem>Close</guimenuitem>
1091                </menuchoice>
1092                item raises a dialog listing the currently open
1093                data tables
1094                (loaded via
1095                <menuchoice>
1096                <guimenu>Table</guimenu>
1097                <guimenuitem>Open</guimenuitem>
1098                </menuchoice>). Selected tables are dereferenced on confirmation.
1099                Since tables are opened read-only the contents of the tables are
1100                not affected.
1101    
1102                Any open views of the tables are closed as well.
1103    
1104                Tables used in a join cannot be closed.
1105                </para>
1106            </section>
1107    
1108            <section><title>Rename</title>
1109                <para>
1110                <menuchoice>
1111                <guimenu>Table</guimenu>
1112                <guimenuitem>Rename</guimenuitem>
1113                </menuchoice> changes the table title.
1114                </para>
1115            </section>
1116    
1117            <section><title>Show</title>
1118                <para>
1119                The
1120                <menuchoice>
1121                <guimenu>Table</guimenu>
1122                <guimenuitem>Show</guimenuitem>
1123                </menuchoice>
1124                item raises a list of available tables (explicitly
1125                loaded, attribute tables, results of a join). Selected tables are
1126                show in tables views on <guibutton>OK</guibutton>.
1127                </para>
1128            </section>
1129    
1130            <section><title>Join</title>
1131                <para>
1132                <screenshot>
1133                <screeninfo>Join Tables</screeninfo>
1134                <mediaobject>
1135                <imageobject><imagedata fileref="../images/7_2_5_join.png" format="PNG" scale="&imgscale;"/></imageobject>
1136                <imageobject><imagedata fileref="./images/7_2_5_join.eps" format="EPS" scale="&imgscale;"/></imageobject>
1137                <textobject><phrase>Join Tables</phrase></textobject>
1138                <caption><para>The Join Tables Dialog</para></caption>
1139                </mediaobject>
1140                </screenshot>
1141                </para>
1142                <para>
1143                The
1144                <menuchoice>
1145                <guimenu>Table</guimenu>
1146                <guimenuitem>Join</guimenuitem>
1147                </menuchoice>
1148                item raises a dialog to specify the two tables to be
1149                joined. The join results in a new table named 'Join of "left table"
1150                and "right table"'.
1151    
1152                The dialog lets you select the two tables to be joined and the two
1153                fields the join has to be performed on. By default, the new
1154                table contains only those records which are matched by the join.
1155    
1156                If you want to preserve the records of the left table you can
1157                perform an outer join. The fields from the right table for records
1158                not matched by the join are filled with <varname>None</varname> in
1159                this case.
1160                </para>
1161            </section>
1162    
1163        </section>
1164        <section><title>Attribute Tables</title>
1165            <para>
1166                To clearly separate between both types of tables (data and
1167            attribute), Thuban provides functionality regarding the attribute
1168            tables under the <menuchoice><guimenu>Layer</guimenu></menuchoice> menu.
1169            </para>
1170    
1171            <section><title>Show Table</title>
1172                <para>
1173                <menuchoice>
1174                <guimenu>Layer</guimenu>
1175                <guimenuitem>Show Table</guimenuitem>
1176                </menuchoice>
1177                opens the attribute table of the currently active layer in a table
1178                view.
1179    
1180                In addition to the functionality described above selections
1181                affect also the map display: objects related to selected records
1182                are highlighted.
1183                </para>
1184            </section>
1185    
1186            <section><title>Join Table</title>
1187                <para>
1188                Unlike the join described above, the join does not result in a
1189                new table. The attribute table of the currently active layer is the
1190                left table and other tables are joined to this table. The results of
1191                the join are available for classification.
1192    
1193                As a consequence, the join cannot result in fewer
1194                records than the source attribute table. The user is warned if the
1195                right table does not fulfill this constraint. An outer join must be
1196                used in such cases.
1197                </para>
1198            </section>
1199    
1200            <section><title>Unjoin Table</title>
1201                <para>
1202                As said above, a normal table cannot be closed while it is still
1203                used in a join. While the joined table resulting from a join of
1204                normal tables can be simply closed (and thereby dereferencing
1205                the source tables), this is not possible for attribute tables.
1206    
1207                Hence joins on attribute tables must be solved explicitly. This is
1208                what the
1209                <menuchoice>
1210                <guimenu>Layer</guimenu>
1211                <guimenuitem>Unjoin Table</guimenuitem>
1212                </menuchoice>
1213                item is used for: The last join for the currently
1214                active layer is solved.
1215                </para>
1216            </section>
1217        </section>
1218    </chapter>    </chapter>
1219    
1220    <chapter><title>Trouble Shooting</title>    <chapter><title>Trouble Shooting</title>
1221      <para>      <para>
1222        Here are a few problems that users have encountered when first using Thuban.
1223        </para>
1224        <para>
1225        <variablelist>
1226    
1227        <varlistentry>
1228        <term>After adding two or more layers nothing is drawn in the map window.
1229        </term>
1230        <listitem>
1231        <para>
1232        This is probably because the layers have different projections. Projections
1233        must be set on all layers and on the map itself if the layers' projections
1234        are different.
1235        </para>
1236        </listitem>
1237        </varlistentry>
1238    
1239        <varlistentry>
1240        <term>Thuban crashes on startup with the error
1241            <literal>NameError: global name 'False' is not defined</literal>.
1242        </term>
1243        <listitem>
1244        <para>
1245        <varname>True</varname> and <varname>False</varname> were only introduced
1246        in Python 2.2.1. Thuban depends on at least Python 2.2.1.
1247      </para>      </para>
1248        </listitem>
1249        </varlistentry>
1250    
1251        <varlistentry>
1252        <term>After compiling Thuban, Thuban crashes with an error similar to
1253            <literal>
1254            ImportError: /usr/local//lib/thuban/Thuban/../Lib/wxproj.so: undefined symbol: __gxx_personality_v0
1255            </literal>
1256        </term>
1257        <listitem>
1258        <para>
1259        Thuban depends on the wxWindows library. If Thuban is compiled with an
1260        incompatible version of the compiler than wxWindows was compiled with
1261        this error may occur. Try compiling with a different version of the
1262        compiler.
1263        </para>
1264        </listitem>
1265        </varlistentry>
1266        </variablelist>
1267        </para>
1268        <para>
1269        If an error occurs Thuban will display a dialog indicating the error
1270        before closing. The text should be copied and reported to the
1271        <ulink url="http://thuban.intevation.org/bugtracker.html">
1272        Intevation bugtracker
1273        </ulink>.
1274        More information about the system is available from
1275        <menuchoice><guimenu>Help</guimenu><guimenuitem>About</guimenuitem></menuchoice> box.
1276        This should also be included in the bug report.
1277        <screenshot>
1278        <screeninfo>Error Dialog</screeninfo>
1279        <mediaobject>
1280        <imageobject><imagedata fileref="../images/8_int_error.png" format="PNG" scale="&imgscale;"/></imageobject>
1281        <imageobject><imagedata fileref="./images/8_int_error.eps" format="EPS" scale="&imgscale;"/></imageobject>
1282        <textobject><phrase>Error Dialog</phrase></textobject>
1283        <caption><para>Error Dialog</para></caption>
1284        </mediaobject>
1285        </screenshot>
1286        </para>
1287    
1288    </chapter>    </chapter>
1289    
1290    <appendix><title>Supported Data Sources</title>    <appendix><title>Supported Data Sources</title>
1291      <para>      <para>
1292      </para>      </para>
1293        <variablelist>
1294        <varlistentry>
1295        <term>Shapefile</term>
1296        <listitem>
1297            <para>
1298            The Shapefile format has become a standard format for saving
1299            geographic vector information. It supports polygons, lines, and
1300            points.
1301            
1302            <ulink url="http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf">
1303            Technical Specification.
1304            </ulink>  
1305            </para>
1306        </listitem>
1307        </varlistentry>
1308    
1309        <varlistentry>
1310        <term>dBase file</term>
1311        <listitem>
1312            <para>
1313            dBase files are used to store the attributes for each layer. This
1314            is closely associated with the Shapefile format. For detailed
1315            specifications on the correct format of a dBase file used with
1316            Thuban please see the Technical Specification for the Shapefile
1317            format above.
1318            </para>
1319        </listitem>
1320        </varlistentry>
1321    
1322        </variablelist>
1323    </appendix>    </appendix>
1324    
1325    <appendix><title>Supported Projections</title>    <appendix><title>Supported Projections</title>
1326      <para>      <para>
1327        The following types of projections are directly support by
1328        Thuban. The specific values for each are provided by the user
1329        to create custom projections. Thuban comes with predefined
1330        projections which are available through the Projections dialog.
1331        </para>
1332        <variablelist>
1333        <varlistentry>
1334            <term>Geographic</term>
1335            <listitem><para><literal>Ellipsoid</literal></para>
1336            <para><literal>Source Data</literal>: either Degrees or Radians
1337                    </para></listitem>
1338        </varlistentry>
1339        <varlistentry>
1340            <term>Lambert Conic Conformal</term>
1341            <listitem><para><literal>Ellipsoid</literal></para>
1342            <para><literal>Latitude of 1st standard parallel</literal></para>
1343            <para><literal>Latitude of 2nd standard parallel</literal></para>
1344            <para><literal>Central Meridian</literal></para>
1345            <para><literal>Latitude of Origin</literal></para>
1346            <para><literal>False Easting</literal> (meters)</para>
1347            <para><literal>False Northing</literal> (meters)</para></listitem>
1348        </varlistentry>
1349        <varlistentry>
1350            <term>Transverse Mercator</term>
1351            <listitem><para><literal>Ellipsoid</literal></para>
1352            <para><literal>Latitude</literal>of origin</para>
1353            <para><literal>Longitude</literal>at central meridian</para>
1354            <para><literal>Scale Factor</literal>at central meridian</para>
1355            <para><literal>False Easting</literal> (meters)</para>
1356            <para><literal>False Northing</literal> (meters)</para></listitem>
1357        </varlistentry>
1358        <varlistentry>
1359            <term>Universal Transverse Mercator</term>
1360            <listitem><para><literal>Ellipsoid</literal></para>
1361            <para><literal>Zone</literal>
1362                    (can be guessed appling the Propose button)</para>
1363            <para><literal>Southern Hemisphere</literal> flag</para></listitem>
1364        </varlistentry>
1365        </variablelist>
1366        
1367        <para>
1368        Thuban comes with a sample set of map projections for various
1369        European countries. Apart from the basic projection they differ
1370        especially in their parameterization:
1371        </para>
1372        <variablelist>
1373        <varlistentry><term>Belgium Datum 1972 (Lambert Conic Conformal)</term>
1374            <listitem><para></para></listitem>
1375        </varlistentry>
1376    
1377        <varlistentry><term>Gauss-Boaga Zone 1 (Italy, Transverse Mercartor)</term>
1378            <listitem><para></para></listitem>
1379        </varlistentry>
1380    
1381        <varlistentry><term>Gauss-Krueger Zone 2 (Germany, Transverse Mercartor)
1382        </term>
1383            <listitem><para></para></listitem>
1384        </varlistentry>
1385    
1386        <varlistentry><term>Reseau Geodesique Francaise
1387        (France, Lambert Conic Conformal)</term>
1388            <listitem><para></para></listitem>
1389        </varlistentry>
1390    
1391        <varlistentry><term>UK National Grid (United Kingdom, Transverse Mercartor)
1392        </term>
1393            <listitem><para></para></listitem>
1394        </varlistentry>
1395        </variablelist>
1396    
1397        <para>
1398        Thuban uses the comprehensive PROJ library for projections. PROJ provides
1399        more than the four commonly used projections described above. If needed
1400        Thuban can be easily extended to a new projection covered by PROJ.
1401      </para>      </para>
1402    </appendix>    </appendix>
1403    
1404  </book>  </book>
1405    
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