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revision 1369 by bh, Thu Jul 3 16:27:22 2003 UTC revision 1490 by jonathan, Mon Jul 28 12:59:47 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>
9      <title>Thuban Manual</title>      <title>Thuban Manual</title>
10      <author>      <author>
11        <firstname></firstname><surname></surname>        <firstname>Jonathan</firstname><surname>Coles</surname>
12        </author>
13        <author>
14          <firstname>Jan-Oliver</firstname><surname>Wagner</surname>
15        </author>
16        <author>
17          <firstname>Frank</firstname><surname>Koormann</surname>
18      </author>      </author>
19      <copyright>      <copyright>
20        <year>2003</year>        <year>2003</year>
# Line 17  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>
47    
48            <section><title>Installation</title>
49            <para>
50            Thuban is actively supported under Debian Testing (sarge), RedHat 7.2,
51            and Windows 2000. All the necessary files can be found on the
52            <ulink url="http://thuban.intevation.org/download.html">
53            Thuban Download site
54            </ulink>.
55            </para>
56            </section>
57    
58            <section><title>The Main Window</title>
59            <para>
60            <screenshot>
61            <screeninfo>The Main Window</screeninfo>
62            <mediaobject>
63            <imageobject> <imagedata fileref="../images/1_2_mainwindow.png" format="PNG" scale="&imgscale;"/> </imageobject>
64            <imageobject> <imagedata fileref="./images/1_2_mainwindow.ps" format="EPS" scale="&imgscale;"/> </imageobject>
65            <textobject><phrase>The Main Window</phrase></textobject>
66            <caption><para>The Main Window</para></caption>
67            </mediaobject>
68            </screenshot>
69            </para>
70    
71            <para>
72            The map window shows the current state of the map and is where
73            the user can interact with the map using the tools.
74            </para>
75    
76            <para>
77            The legend on the left displays a list of the current layers and
78            any visible classification groups. In the example, each shape layer
79            has a default classification which specifies how the shapes in each
80            layer are drawn. Layers that are higher in the list appear
81            ``closer'' to the user. The legend can be closed by clicking on the
82            small X in the upper right-hand region of the legend.
83            To open it again, use
84            <menuchoice>
85            <guimenu>Map</guimenu>
86            <guimenuitem>Legend</guimenuitem>
87            </menuchoice>.
88            The legend is also dockable, which means that it can be detached
89            from the main window by clicking on the small button next to the
90            close button. It can be attached by clicking the same button
91            again.
92            </para>
93            <para>
94            The status bar displays different information depending on the
95            current context. If the user is selecting an item from the menu
96            then the status bar will display a short help message indicating
97            what each menu item is for. If the user has a tool selected then
98            the position of the cursor on the map is displayed.
99            </para>
100            <para>
101            The tool bar provides quick access to the commonly needed tools.
102            By hovering over each button the user can see a short messages
103            describing what the tool does. The tools provided are Zoom In, Zoom
104            Out, Pan, Full Extent, Full Layer Extent, Full Shape Extent, Indentify,
105            and Label. Each of the tools will be explained in further detail later
106            in the manual.
107            </para>
108            </section>
109    
110      </chapter>
111    
112      <chapter><title>Session Management</title>
113    
114            <section><title>Starting a New Session</title>
115            <para>
116            A new session can be started from
117            <menuchoice>
118            <guimenu>File</guimenu>
119            <guimenuitem>New Session</guimenuitem>
120            </menuchoice>.
121            If a session is already loaded and has been modified without
122            being saved a prompt will ask if the current session should
123            be saved. A new session consists of an empty map with no
124            layers and no tables.
125            </para>
126            </section>
127    
128            <section><title>Opening a Session</title>
129            <para>
130            A session can be opened from
131            <menuchoice>
132            <guimenu>File</guimenu>
133            <guimenuitem>Open Session</guimenuitem>
134            </menuchoice>. A dialog box will open allowing the user to browse
135            for a Thuban Session file. Thuban session files end with
136            <varname>.thuban</varname>. Selecting a file a clicking
137            <guibutton>OK</guibutton> will load the session into Thuban.
138    
139            If a session is already loaded and has been modified without
140            being saved a prompt will ask if the current session should
141            be saved.
142            </para>
143            </section>
144    
145            <section><title>Saving a Session</title>
146            <para>
147            A session can be saved from
148            <menuchoice>
149            <guimenu>File</guimenu>
150            <guimenuitem>Save Session</guimenuitem>
151            </menuchoice>. A dialog box will open allowing the user to browse
152            the filesystem and select a place to save the session. Thuban
153            sessions should be saved under a name ending in
154            <varname>.thuban</varname>. If the file already exists the user
155            will be prompted to save under a different name or overwrite the
156            existing file.
157            </para>
158            </section>
159    
160            <section><title>The Session Info-Tree</title>
161            <para>
162            <screenshot>
163            <screeninfo>Session Info Tree</screeninfo>
164            <mediaobject>
165            <imageobject><imagedata fileref="../images/2_4_session_tree.png" format="PNG" scale="&imgscale;"/></imageobject>
166            <imageobject><imagedata fileref="./images/2_4_session_tree.eps" format="EPS" scale="&imgscale;"/></imageobject>
167            <textobject><phrase>Session Info Tree</phrase></textobject>
168            <caption><para>Session Info Tree</para></caption>
169            </mediaobject>
170            </screenshot>
171            </para>
172            <para>
173            The session info-tree is primarily intended for developers working
174            with Thuban. It displays many of the internal values for the session,
175            map, and layers. It can be opened from
176            <menuchoice>
177            <guimenu>File</guimenu>
178            <guimenuitem>Session Tree</guimenuitem>
179            </menuchoice>.
180            </para>
181            </section>
182      </chapter>
183    
184      <chapter><title>Map Management</title>
185        <para>
186        The map consists of a number of layers where each layer represents a
187        different type of data set. By interacting with the map the user can
188        visually explore the data.
189        </para>
190        <para>
191        The map can have a name that will appear in the Thuban title bar.
192        The map name can be changed using
193        <menuchoice>
194        <guimenu>Map</guimenu>
195        <guimenuitem>Rename</guimenuitem>
196        </menuchoice>.
197        </para>
198        <para>
199        <inlinemediaobject>
200        <imageobject>
201        <imagedata fileref="../images/3_rename_map.png" format="PNG" scale="&imgscale;"/>
202        </imageobject>
203        <imageobject>
204        <imagedata fileref="./images/3_rename_map.eps" format="EPS" scale="&imgscale;"/>
205        </imageobject>
206        <textobject> <phrase>Rename Map</phrase> </textobject>
207        </inlinemediaobject>
208        </para>
209    
210            <section><title>Adding and Removing Layers</title>
211            <para>
212            There are two types of layers that can use added to a map: shape layers
213            and image layers. Shape layers are stored in Shapefile format, a
214            standard file format for storing geographic objects. Normally, these
215            files have the extension ``.shp''. Associated with
216            the object information is a database file which stores attributes for
217            each shape in the Shapefile. This file, stored in dBASE format, usually
218            has the extension ``.dbf''. Both files should have the same base name.
219            For example, if there is a Shapefile named roads.shp there should
220            also be a file roads.dbf.
221            </para>
222            <para>
223            Shape layers can be added to the map with
224            <menuchoice>
225            <guimenu>Map</guimenu>
226            <guimenuitem>Add Layer</guimenuitem>
227            </menuchoice>.
228            Thuban will load all files with the same base name, so it doesn't
229            matter if the Shapefile or database file is selected.
230            </para>
231    
232            <para>
233            Image layers can be added to the map with
234            <menuchoice>
235            <guimenu>Map</guimenu>
236            <guimenuitem>Add Image Layer</guimenuitem>
237            </menuchoice>.
238            It is important to select a valid image file that has geographic
239            data associated with it. This can be embedded in the file itself,
240            or in another file. If geographic information cannot be found, Thuban
241            will report an error.
242            </para>
243            </section>
244    
245            <section><title>Navigation</title>
246            <para>
247            The map can be explored by using the navigation tools available on
248            the tool bar, or from the
249            <menuchoice><guimenu>Map</guimenu></menuchoice> menu.
250            </para>
251            <para>
252            The ZoomIn tool
253            <inlinemediaobject>
254            <imageobject>
255            <imagedata fileref="../images/3_2_zoomin.png" format="PNG" scale="&imgscale;"/>
256            </imageobject>
257            <imageobject>
258            <imagedata fileref="./images/3_2_zoomin.eps" format="EPS" scale="&imgscale;"/>
259            </imageobject>
260            <textobject> <phrase>ZoomIn Tool</phrase> </textobject>
261            </inlinemediaobject>
262            can be used to enlarge a region of the map. Clicking once on the map
263            will double the magnification and center the map on the point that
264            was clicked. Clicking and dragging lets the user select a region
265            to be enlarged to fit the window.
266            </para>
267            <para>
268            The ZoomOut tool
269            <inlinemediaobject>
270            <imageobject>
271            <imagedata fileref="../images/3_2_zoomout.png" format="PNG" scale="&imgscale;"/>
272            </imageobject>
273            <imageobject>
274            <imagedata fileref="./images/3_2_zoomout.eps" format="EPS" scale="&imgscale;"/>
275            </imageobject>
276            <textobject> <phrase>ZoomOut Tool</phrase> </textobject>
277            </inlinemediaobject>
278            shrinks the map so that a larger region is visible. A single click
279            reduces the magnification by a factor of two. Clicking and dragging
280            selects a box such that the current contents of the window will be
281            scaled to fit into that box.
282            </para>
283            <para>
284            The Pan tool
285            <inlinemediaobject>
286            <imageobject>
287            <imagedata fileref="../images/3_2_pan.png" format="PNG" scale="&imgscale;"/>
288            </imageobject>
289            <imageobject>
290            <imagedata fileref="./images/3_2_pan.eps" format="EPS" scale="&imgscale;"/>
291            </imageobject>
292            <textobject> <phrase>Pan Tool</phrase> </textobject>
293            </inlinemediaobject>
294            allows the user to move the map around by clicking and dragging.
295            </para>
296            <para>
297            The Full Extent tool
298            <inlinemediaobject>
299            <imageobject>
300            <imagedata fileref="../images/3_2_fullextent.png" format="PNG" scale="&imgscale;"/>
301            </imageobject>
302            <imageobject>
303            <imagedata fileref="./images/3_2_fullextent.eps" format="EPS" scale="&imgscale;"/>
304            </imageobject>
305            <textobject> <phrase>Full Extent Tool</phrase> </textobject>
306            </inlinemediaobject>
307            rescales the viewable region so that the entire map is visible.
308            </para>
309            <para>
310            The Full Layer Extent tool
311            <inlinemediaobject>
312            <imageobject>
313            <imagedata fileref="../images/3_2_fulllayerextent.png" format="PNG" scale="&imgscale;"/>
314            </imageobject>
315            <imageobject>
316            <imagedata fileref="./images/3_2_fulllayerextent.eps" format="EPS" scale="&imgscale;"/>
317            </imageobject>
318            <textobject> <phrase>Full Layer Extent Tool</phrase> </textobject>
319            </inlinemediaobject>
320            rescales the viewable region so that the currently selected
321            layer fits within the window. If no layer is selected this button
322            will be disabled.
323            </para>
324            <para>
325            The Full Shape Extent tool
326            <inlinemediaobject>
327            <imageobject>
328            <imagedata fileref="../images/3_2_fullshapeextent.png" format="PNG" scale="&imgscale;"/>
329            </imageobject>
330            <imageobject>
331            <imagedata fileref="./images/3_2_fullshapeextent.eps" format="EPS" scale="&imgscale;"/>
332            </imageobject>
333            <textobject> <phrase>Full Shape Extent Tool</phrase> </textobject>
334            </inlinemediaobject>
335            rescales the viewable region so that the currently selected
336            shape fits within the window. If the shape is a point, it is
337            centered and the map is zoomed all the way in. If no shape is
338            selected this button will be disabled.
339            </para>
340            </section>
341    
342            <section><title>Object Identification</title>
343            <para>
344            Objects on the map can be identified using the Identify tool
345            <inlinemediaobject>
346            <imageobject>
347            <imagedata fileref="../images/3_3_identify.png" format="PNG" scale="&imgscale;"/>
348            </imageobject>
349            <imageobject>
350            <imagedata fileref="./images/3_3_identify.eps" format="EPS" scale="&imgscale;"/>
351            </imageobject>
352            <textobject> <phrase>Identify Tool</phrase> </textobject>
353            </inlinemediaobject>.
354            Clicking on an object selects that object and opens a dialog which
355            shows all the table attributes for that object. Any current selection
356            is lost.
357            </para>
358            </section>
359    
360            <section><title>Object Labelling</title>
361            <para>
362            Objects can be labelled using the Label tool
363            <inlinemediaobject>
364            <imageobject>
365            <imagedata fileref="../images/3_3_label.png" format="PNG" scale="&imgscale;"/>
366            </imageobject>
367            <imageobject>
368            <imagedata fileref="./images/3_3_label.eps" format="EPS" scale="&imgscale;"/>
369            </imageobject>
370            <textobject> <phrase>Label Tool</phrase> </textobject>
371            </inlinemediaobject>.
372            Clicking on an object selects that object and opens a dialog which
373            displays the table attributes for that object. An attribute can
374            be selected to be the label on the map. Using this tool for an
375            object that already has a label will remove the label.
376            </para>
377            </section>
378    
379            <section><title>The Legend</title>
380            <para>
381            <inlinemediaobject>
382            <imageobject>
383            <imagedata fileref="../images/3_5_legend.png" format="PNG" scale="&imgscale;"/>
384            </imageobject>
385            <imageobject>
386            <imagedata fileref="./images/3_5_legend.eps" format="EPS" scale="&imgscale;"/>
387            </imageobject>
388            <textobject> <phrase>Legend</phrase> </textobject>
389            </inlinemediaobject>
390            </para>
391            <para>
392            The Legend provides an overview of the layers in the map. Layers
393            that appear higher in the legend will appear ``closer'' to the user.
394            If a layer supports classification (currently, only shape layers
395            have this feature) then the classification groups will be shown
396            below each layer. The properties for each group are also displayed
397            with a small graphic. Polygon layers appear as rectangles, lines
398            appear as curved lines, and points appear as circles.
399            </para>
400            <para>
401            Along the top of the legend is a toolbar which allows quick access
402            to some of the layer manipulation options under
403            <menuchoice> <guimenu>Map</guimenu> </menuchoice>.
404    
405            Double-clicking on a layer or a group of a layer will open the
406            properties dialog for that layer.
407            </para>
408            </section>
409    
410            <section><title>Exporting</title>
411            <para>
412            Under Windows, maps can be exported in Enhanced Metafile format
413            (<varname>.wmf</varname>)
414            from
415            <menuchoice>
416            <guimenu>Map</guimenu>
417            <guimenuitem>Export</guimenuitem>
418            </menuchoice>. Under other platforms this option is not available.
419            Clicking this menu item open a file selection dialog that lets the
420            user select a location to export the map.
421            </para>
422            </section>
423    
424            <section><title>Printing</title>
425            <para>
426            The map can be printed using
427            <menuchoice>
428            <guimenu>Map</guimenu>
429            <guimenuitem>Print</guimenuitem>
430            </menuchoice>. A standard printing dialog will open allowing the
431            user to configure the printer. This dialog will differ depending
432            on which platform Thuban is running.
433            </para>
434            </section>
435    
436      </chapter>
437    
438      <chapter><title>Layer Management</title>
439        <para>
440        </para>
441    
442            <section><title>Types of Layers</title>
443            <para>
444            There are two types of layers supported by Thuban: shape layers and
445            image layers. Shape layers consist of vector based shapes with
446            geo-referenced coordinates. There are three types of supported
447            shapes: polygons, lines, and points. Image layers can be any image
448            file format supported by GDAL. The images must have geographic
449            coordinate data either embedded within the file, or in a seperate
450            file that is in the same directory as the image file. GeoTIFF files
451            work very well with Thuban and were designed specifically to be image
452            layers in GIS programs.
453            </para>
454            </section>
455    
456            <section><title>Properties</title>
457            <para>
458            To view the properties for a layer it must first be selected in the
459            legend. The menu option
460            <menuchoice>
461            <guimenu>Layer</guimenu>
462            <guimenuitem>Properties</guimenuitem>
463            </menuchoice> opens a dialog that displays a layer's properties.
464            All layers have a title and it can be modified in the text field
465            provided. The type of layer is also shows. If the type is type
466            of shape (polygon, arc, point) the classification table will be
467            shown. Image layers have no other properties other than title
468            and type.
469            </para>
470            <para>
471            <screenshot>
472            <screeninfo>Properties Window</screeninfo>
473            <mediaobject>
474            <imageobject><imagedata fileref="../images/4_2_layer_properties.png" format="PNG" scale="&imgscale;"/></imageobject>
475            <imageobject><imagedata fileref="./images/4_2_layer_properties.eps" format="EPS" scale="&imgscale;"/></imageobject>
476            <textobject><phrase>Properties Window</phrase></textobject>
477            <caption><para>The Properties Window for a Shape Layer</para></caption>
478            </mediaobject>
479            </screenshot>
480            </para>
481            <para>
482            <screenshot>
483            <screeninfo>Properties Window</screeninfo>
484            <mediaobject>
485            <imageobject><imagedata fileref="../images/4_2_raster_layer_properties.png" format="PNG" scale="&imgscale;"/></imageobject>
486            <imageobject><imagedata fileref="./images/4_2_raster_layer_properties.eps" format="EPS" scale="&imgscale;"/></imageobject>
487            <textobject><phrase>Properties Window</phrase></textobject>
488            <caption><para>The Properties Window for an Image Layer</para></caption>
489            </mediaobject>
490            </screenshot>
491            </para>
492            </section>
493    
494            <section><title>Visibility</title>
495            <para>
496            Sometimes it is not desirable to view all layers at the same time.
497            Some layers may take a long time to draw and so while navigating
498            around the map the user may not want to wait for the map to redraw
499            each time the map is changed. Each layer can be independently
500            turned on or off using the
501            <menuchoice>
502            <guimenu>Layer</guimenu>
503            <guimenuitem>Show</guimenuitem>
504            </menuchoice>
505            or
506            <menuchoice>
507            <guimenu>Layer</guimenu>
508            <guimenuitem>Hide</guimenuitem>
509            </menuchoice> options respectively.
510            </para>
511            </section>
512    
513            <section><title>Duplication</title>
514            <para>
515            Layers and all their properties, including classifications, can
516            be duplicated using
517            <menuchoice>
518            <guimenu>Layer</guimenu>
519            <guimenuitem>Duplicate</guimenuitem>
520            </menuchoice>. Duplicating a layer is useful if the user wishes
521            to model a layer in several different ways. Even though the layers
522            overlap by carefully selecting the shape properties it is possible
523            to display several pieces of information at once. For example, one
524            copy of a roads layer may be classified on a length property and
525            another copy may be classified on a type property. if the length
526            property was expressed with color and the type property expressed
527            with line thickness then it would be possible to view both
528            classifications by placing the type property copy over the
529            length property copy.
530            </para>
531            </section>
532    
533      </chapter>
534    
535      <chapter><title>Layer Classifications</title>
536        <para>
537        A layer classification is a way of assigning drawing properties to
538        groups of shapes based on attributes stored in the layer's table.
539        Only layer's with shapes can have a classification; image layers
540        cannot be classified.
541        </para>
542        <para>
543        A classification consists of a number of groups, with each group
544        having a value or range of values to match against, and symbol
545        properties which control how a shape is drawn on the map. The user
546        selects which field in the table is used by the classification and
547        when the map is drawn the value for that field for each shape is
548        compared with each group's value. The properties of the first group
549        to match are used to draw the shape. This allows the user to get a
550        visual impression of not only how the data is laid out but also what
551        kind of data lies where.
552        </para>
553        <para>
554        A layer always has a classification. When a new layer is added to the
555        map, a default classification is created with the DEFAULT group. This
556        group cannot be removed. Every shape in the layer, regardless of its
557        attributes, will match this group.
558      </para>      </para>
559    
560            <section><title>Editing Classifications</title>
561            <para>
562            A layer's classification can be modified under the properties dialog
563            (<menuchoice>
564            <guimenu>Layer</guimenu>
565            <guimenuitem>Properties</guimenuitem>
566            </menuchoice>). The layer's classification field can be set to None,
567            which simply assigns a DEFAULT group to the classification. No new
568            groups can be added to the classification if the field is None.
569            The user must first select a field to classify on. New groups can
570            be added to the classification with the <guibutton>Add</guibutton>
571            button.
572            </para>
573            <para>
574            <screenshot>
575            <screeninfo>Properties Window</screeninfo>
576            <mediaobject>
577            <imageobject><imagedata fileref="../images/5_classification.png" format="PNG" scale="&imgscale;"/></imageobject>
578            <imageobject><imagedata fileref="./images/5_classification.eps" format="EPS" scale="&imgscale;"/></imageobject>
579            <textobject><phrase>Properties Window</phrase></textobject>
580            <caption><para>The Properties Window with Classifications</para></caption>
581            </mediaobject>
582            </screenshot>
583            </para>
584            <para>
585            The order of the groups in the classification is significant
586            except for the DEFAULT group, which remains at the top. When shapes
587            are matched against groups the matching begins at the first group
588            other than the DEFAULT group so that groups higher in the list will
589            be checked first. Matching for a
590            given shape will stop at the first group that matches. The user can
591            use <guibutton>Move Up</guibutton> and <guibutton>Move Down</guibutton>
592            to change the order of the groups. The DEFAULT group will always
593            match a shape that hasn't matched another group.
594            </para>
595            <para>
596            The Value column of the classification table is the value that will
597            be matched when the map is being drawn. The type of data that can
598            entered into this field depends on the type of data of the
599            classification field.
600            </para>
601            <para>
602            If the field is of type Text, anything entered
603            into the field is valid. The text will be compared literally to the
604            value of the shape attribute, including case sensitivity.
605            If the type is Integer, then any valid integer may be entered. In
606            addition, with special syntax, a range of values can be entered.
607            A range from <varname>start</varname> to <varname>end</varname>
608            inclusive is specifed like this: <literal>[start;end]</literal>.
609            The exclusive range is specified like this:
610            <literal>]start;end[</literal>. Ranges can include infinity like
611            this: <literal>[-oo;oo]</literal>. Field types can also be of type
612            Decimal. They represent any rational number and can be used in ranges
613            as well.
614            </para>
615            </section>
616    
617            <section><title>Symbols</title>
618            <para>
619            Each type of shape has its own type of symbol. Thuban supports three
620            types of shapes: polygons, lines, and points. Polygons and points have
621            outline and fill color, while lines have only line color. Each group
622            has associated symbol properties. To edit the symbol properties for a
623            group the user can double click on the Symbol column or select a
624            group and click the <guibutton>Edit Symbol</guibutton> button.
625            </para>
626            </section>
627    
628            <section><title>Generating Classes</title>
629            <para>
630            <screenshot>
631            <screeninfo>Generate Class</screeninfo>
632            <mediaobject>
633            <imageobject><imagedata fileref="../images/5_3_genclass.png" format="PNG" scale="&imgscale;"/></imageobject>
634            <imageobject><imagedata fileref="./images/5_3_genclass.eps" format="EPS" scale="&imgscale;"/></imageobject>
635            <textobject><phrase>Generate Class</phrase></textobject>
636            <caption><para>The Generate Classifications Dialog</para></caption>
637            </mediaobject>
638            </screenshot>
639            </para>
640            <para>
641            Creating a classification by hand can be tedious.
642            Thuban, therefore, provides a means of generating an entire
643            classification at once while still giving the user control over
644            how it appears. Clicking <guibutton>Generate Class</guibutton>
645            opens the <varname>Generate Classification</varname> dialog.
646            Under the <varname>Generate</varname> pulldown there are at most
647            three different ways to generate classifications:
648            Unique Values, Unique Distribution, and Quantiles. Some options
649            may not be available if they data type for the field does not
650            support them. For instance, <varname>Unique Distribution</varname>
651            doesn't make sense for a Text field.
652            </para>
653            <para>
654            For every way of generating a classification, a color scheme must
655            be selected. Thuban provides several different color schemes that
656            affect how the group properties change over the classification.
657            It is also possible to create a custom color scheme. Selecting
658            this option will display two symbols: the one of the left has the
659            properties of the first group and the one on the right has the
660            properties of the last group. Thuban will interpolate between these
661            two properties to generate the other groups.
662            </para>
663            <para>
664            The Unique Values option lets the user select specific values that
665            appear in the table. Clicking <guibutton>Retrieve From Table</guibutton>
666            searches the table for all unique values and displays them in the
667            list on the left. Items can be selected and moved to the list on the
668            right. Each list can be sorted or reversed for easier searching.
669            The classification that is generated will be in the same order as
670            the list on the right.
671            </para>
672            <para>
673            The Unique Distribution option creates a user specified number of
674            groups of ranges such that each range covers equal intervals. The
675            minimum and maximum values can automatically be retrieved from the
676            table by clicking <guibutton>Retrieve From Table</guibutton>. The
677            stepping is how large each interval is. Adjusting this value will
678            automatically recalculate how many groups is appropriate.
679            </para>
680            <para>
681            The Quantiles option generates ranges based on the number items
682            in the input set. For example, by specifying 5 groups Thuban will
683            generate groups with appropriate ranges such that 20% of the table
684            data is in each group. If it is impossible to generate exact
685            grouping, Thuban will issue a warning but allow the user to continue.
686            </para>
687            </section>
688      </chapter>
689    
690      <chapter><title>Projection Management</title>
691        <para>
692        Projections control how the geographic data is displayed on the screen.
693        If multiple layers are loaded into Thuban where the geographic data
694        is in a different projection system, then the user must tell Thuban
695        which projection each layer has. The user must also tell Thuban which
696        projection the map is in. This can be the same as the layers or a different
697        projection in which case the layers are reprojected into that space.
698        The map projection can be set using
699        <menuchoice>
700        <guimenu>Map</guimenu>
701        <guimenuitem>Projection</guimenuitem>
702        </menuchoice> and the layer projection can be set using
703        <menuchoice>
704        <guimenu>Layer</guimenu>
705        <guimenuitem>Projection</guimenuitem>
706        </menuchoice>.
707        <screenshot>
708        <screeninfo>Projection Window</screeninfo>
709        <mediaobject>
710        <imageobject><imagedata fileref="../images/6_projection.png" format="PNG" scale="&imgscale;"/></imageobject>
711        <imageobject><imagedata fileref="./images/6_projection.eps" format="EPS" scale="&imgscale;"/></imageobject>
712        <textobject><phrase>Projection Window</phrase></textobject>
713        <caption><para>The Projection Window</para></caption>
714        </mediaobject>
715        </screenshot>
716        </para>
717        <para>
718        Thuban is distributed with a sample collection of projections. The
719        user can create new projections and make them available to all
720        future Thuban sessions. They may also be exported and imported so
721        that custom projections can be distributed to others.
722        </para>
723            <section><title>Selecting a Projection</title>
724            <para>
725            The available projections are listed on the left. If the layer
726            or map already has a projection it will be initially highlighted
727            and will end with <varname>(current)</varname>. Selecting
728            <varname>&lt;None&gt;</varname> will cause Thuban to use the data as
729            it appears in the source file and will not use a projection.
730            </para>
731        </section>
732            <section><title>Editing a Projection</title>
733            <para>
734            Whenever a projection is selected from the list its properties
735            are displayed on the right. These properties can be changed
736            and the changes saved to the selected projection using
737            the <guibutton>Update</guibutton>. Only a projection that comes
738            from a file can be updated, so if the current layer's projection
739            is selectd, <guibutton>Update</guibutton> will be disabled.
740            The <guibutton>Add to List</guibutton> adds the projection to the
741            list of available projections as a new entry, and thus make it
742            available to future Thuban sessions. Clicking <guibutton>New</guibutton>
743            will create an entirely new, empty projection. The
744            <guibutton>Remove</guibutton> button will permanantly remove a
745            projection from the list of available projections.
746            </para>
747        </section>
748            <section><title>Importing/Exporting Projections</title>
749            <para>
750            The projections that appear in the list of available projections
751            can be exported to another file that the user chooses. By selecting
752            one or more projections and clicking <guibutton>Export</guibutton>
753            the user will be able to select a file to store those projections.
754            The file can then be distributed to other Thuban users. To import
755            a projection file the user can click <guibutton>Import</guibutton>.
756            The imported projections are added to the list and are then available
757            to the current session and any future Thuban session.
758            </para>
759        </section>
760    </chapter>    </chapter>
761    
762      <chapter><title>Table Management</title>
763        <para>
764        Thuban distinguishes two different types of tables: Attribute tables
765        (which belong to a layer) and usual data tables. Both provide in
766            general the same functionality with the difference that actions on an
767        attribute table might also effect the map display.
768        </para>
769    
770        <section><title>Table View</title>
771            <para>
772            <screenshot>
773            <screeninfo>Table View</screeninfo>
774            <mediaobject>
775            <imageobject><imagedata fileref="../images/7_1_table_view.png" format="PNG" scale="&imgscale;"/></imageobject>
776            <imageobject><imagedata fileref="./images/7_1_table_view.eps" format="EPS" scale="&imgscale;"/></imageobject>
777            <textobject><phrase>Table View</phrase></textobject>
778            <caption><para>The Table View</para></caption>
779            </mediaobject>
780            </screenshot>
781            </para>
782            <para>
783            Thuban provides a standard dialog to display table contents, the
784            Table View. The view falls into five sections: The title, selections,
785            the table grid, export functions and the status bar.
786            </para>
787            <para>
788            The title bar identifies the table with it's name.
789            </para>
790            <para>
791            The functions box let the user perform simple analysis on the data
792            based on comparisons: First choice must be a field identifier of the
793            table, the second choice determines the type of comparison. The third
794            choice can be either a specific value (interpreted as numerical
795            or string depending on the type of the first field) or a second field
796            identifier. Thus you can perform analysis like selecting all
797            records where "population > 10000" or
798            "cars_per_habitants <  bike_per_habitants" (note that the field names
799            are only explanatory, the currently considered dBASE files allow only
800            11 character field names).
801          
802            Selections can be combined, either by applying a selection only on
803            a previously selected set of records or by adding the results of a
804            selection to a previous set. The default is that a selection replaces
805            earlier results.
806            </para>
807            <para>
808            The table grid shows the contents of the table (a record per column),
809            with highlighted selection results. Columns and rows can be resized.
810            </para>
811            <para>
812            The contents of a table can be exported into a file, either dBASE
813            format (DBF) or comma seperated values (CSV). The
814            <guibutton>Export</guibutton> button
815            raises a file dialog to specify a path and file name, the export type
816            is determined by the file extension (either .dbf or .csv).
817    
818            The <guibutton>Export Selection</guibutton> button works similarly
819            but exports only the selected records.
820    
821            The <guibutton>Close</guibutton> button closes the table view window.
822            This is different from the menu item
823            <menuchoice>
824            <guimenu>Table</guimenu>
825            <guimenuitem>Close</guimenuitem>
826            </menuchoice> which unloads the table from Thuban.
827            </para>
828            <para>
829            The status bar displays some statistics about the table and optional
830            selection results.
831            </para>
832        </section>
833    
834        <section><title>General Functionality (Menu Table)</title>
835            <para>
836            The general functions affect all tables open in Thuban. Attribute
837            tables are considered here as usual data tables (with the exception
838            that they cannot be closed).
839            </para>
840            <section><title>Open</title>
841                <para>
842                The
843                <menuchoice>
844                <guimenu>Table</guimenu>
845                <guimenuitem>Open</guimenuitem>
846                </menuchoice>
847                item raises a file dialog to let you select a
848                dBASE file from the file system to be loaded into Thuban read-only.
849                On OK the selected file is loaded and a table view is opened.
850                </para>
851            </section>
852    
853            <section><title>Close</title>
854                <para>
855                The
856                <menuchoice>
857                <guimenu>Table</guimenu>
858                <guimenuitem>Close</guimenuitem>
859                </menuchoice>
860                item raises a dialog listing the currently open
861                data tables
862                (loaded via
863                <menuchoice>
864                <guimenu>Table</guimenu>
865                <guimenuitem>Open</guimenuitem>
866                </menuchoice>). Selected tables are dereferenced on confirmation.
867                Since tables are opened read-only the contents of the tables are
868                not affected.
869    
870                A still open table view is closed as well.
871    
872                Tables used in a join cannot be closed.
873                </para>
874            </section>
875    
876            <section><title>Rename</title>
877                <para>
878                <menuchoice>
879                <guimenu>Table</guimenu>
880                <guimenuitem>Rename</guimenuitem>
881                </menuchoice> changes the table title.
882                </para>
883            </section>
884    
885            <section><title>Show</title>
886                <para>
887                The
888                <menuchoice>
889                <guimenu>Table</guimenu>
890                <guimenuitem>Show</guimenuitem>
891                </menuchoice>
892                item raises a list of available tables (explicitly
893                loaded, attribute tables, results of a join). Selected tables are
894                show in tables views on <guibutton>OK</guibutton>
895                </para>
896            </section>
897    
898            <section><title>Join</title>
899                <para>
900                <screenshot>
901                <screeninfo>Join Tables</screeninfo>
902                <mediaobject>
903                <imageobject><imagedata fileref="../images/7_2_5_join.png" format="PNG" scale="&imgscale;"/></imageobject>
904                <imageobject><imagedata fileref="./images/7_2_5_join.eps" format="EPS" scale="&imgscale;"/></imageobject>
905                <textobject><phrase>Join Tables</phrase></textobject>
906                <caption><para>The Join Tables Dialog</para></caption>
907                </mediaobject>
908                </screenshot>
909                </para>
910                <para>
911                The
912                <menuchoice>
913                <guimenu>Table</guimenu>
914                <guimenuitem>Join</guimenuitem>
915                </menuchoice>
916                item raises a dialog to specify the two tables to be
917                joined. The join results in a new table named 'Join of "left table"
918                and "right table"'.
919    
920                The dialog let you select the two tables to be joined and the two
921                fields the join has to be performed on. By default the new
922                table contains only those records which are mathced by the join.
923    
924                If you want to preserve the records of the left table you can
925                perform an outer join. The fields from the right table for records
926                not matched by the join are filled with <varname>None</varname> in
927                this case.
928                </para>
929            </section>
930    
931        </section>
932        <section><title>Attribute Tables</title>
933            <para>
934                To clearly separate between both types, Thuban provides
935            functionality regarding the attribute tables under the Layer menu.
936            </para>
937    
938            <section><title>Show Table</title>
939                <para>
940                <menuchoice>
941                <guimenu>Layer</guimenu>
942                <guimenuitem>Show Table</guimenuitem>
943                </menuchoice>
944                opens the attribute table of the currently active layer in a table
945                view.
946    
947                In addition to the functionality described above selections
948                affect also the map display: objects related to selected records
949                are highlighted.
950                </para>
951            </section>
952    
953            <section><title>Join Table</title>
954                <para>
955                In difference to the join described above the join results not in a
956                new table. The attribute table of the currently active layer is the
957                left table and other tables are joined to this table. The results of
958                the join are available for classifications.
959    
960                As a consequence, the join cannot result in fewer
961                records than the source attribute table. The user is warned if the
962                right table does not fulfill this constraint. An outer join must be
963                used in such cases.
964                </para>
965            </section>
966    
967            <section><title>Unjoin Table</title>
968                <para>
969                As said above, a normal table cannot be closed while it is still
970                used in a join. While the joined table resulting from a join of
971                normal tables can be simply closed (and thereby dereferencing
972                the source tables), this is not possible for attribute tables.
973    
974                Hence joins on attribute tables must be solved explicitely. This is
975                what the
976                <menuchoice>
977                <guimenu>Layer</guimenu>
978                <guimenuitem>Unjoin Table</guimenuitem>
979                </menuchoice>
980                item is used for: The last join for the currently
981                active layer is solved.
982                </para>
983            </section>
984        </section>
985      </chapter>
986    
987      <chapter><title>Trouble Shooting</title>
988        <para>
989        </para>
990        <variablelist>
991    
992        <varlistentry>
993        <term>After adding two or more layers nothing is being drawn in the
994        map window.
995        </term>
996        <listitem>
997        <para>
998        This is probably because the layers have different projections. Projections
999        must be set on all layers and on the map itself if the layer's projections
1000        are different.
1001        </para>
1002        </listitem>
1003        </varlistentry>
1004    
1005        <varlistentry>
1006        <term>Thuban crashes on startup with the error
1007            <literal>NameError: global name 'False' is not defined</literal>.
1008        </term>
1009        <listitem>
1010        <para>
1011        <varname>True</varname> and <varname>False</varname> were only introduced
1012        in Python 2.2.1. Thuban depends on at least Python 2.2.1.
1013        </para>
1014        </listitem>
1015        </varlistentry>
1016    
1017        <varlistentry>
1018        <term>After compiling Thuban, Thuban crashes with an error similar to
1019            <literal>
1020            ImportError: /usr/local//lib/thuban/Thuban/../Lib/wxproj.so: undefined symbol: __gxx_personality_v0
1021            </literal>
1022        </term>
1023        <listitem>
1024        <para>
1025        Thuban depends on the wxWindows library. If Thuban is compiled with an
1026        incompatible version of the compiler that wxWindows was compiled with
1027        this error may occur. Try compiling with a different version of the
1028        compilere
1029        </para>
1030        </listitem>
1031        </varlistentry>
1032        </variablelist>
1033    
1034      </chapter>
1035    
1036      <appendix><title>Supported Data Sources</title>
1037        <para>
1038        </para>
1039        <variablelist>
1040        <varlistentry>
1041        <term>Shapefile</term>
1042        <listitem>
1043            <para>
1044            The Shapefile format has become a standard format for saving
1045            geographic vector information. It supports polygons, lines, and
1046            points.
1047            
1048            <ulink url="http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf">
1049            Technical Specification.
1050            </ulink>  
1051            </para>
1052        </listitem>
1053        </varlistentry>
1054    
1055        <varlistentry>
1056        <term>dBASE file</term>
1057        <listitem>
1058            <para>
1059            dBASE files are used to store the attributes for each layer. This
1060            is closely associated with the Shapefile format. For detailed
1061            specifications on the correct format of a dBASE file used with
1062            Thuban please see the Technical Specification for the Shapefile
1063            format above.
1064            </para>
1065        </listitem>
1066        </varlistentry>
1067    
1068        </variablelist>
1069      </appendix>
1070    
1071      <appendix><title>Supported Projections</title>
1072        <para>
1073        The following types of projections are directly support by
1074        Thuban. The specific values for each are provided by the user
1075        to create custom projections. Thuban comes with predefined
1076        projections and are available through the Projections dialog.
1077        </para>
1078        <variablelist>
1079        <varlistentry>
1080        <term>Geographic</term>
1081        <listitem><para></para></listitem>
1082        </varlistentry>
1083        <varlistentry>
1084        <term>Lambert Conic Conformal</term>
1085        <listitem><para></para></listitem>
1086        </varlistentry>
1087        <varlistentry>
1088        <term>Transverse Mercator</term>
1089        <listitem><para></para></listitem>
1090        </varlistentry>
1091        <varlistentry>
1092        <term>Universal Transverse Mercator</term>
1093        <listitem><para></para></listitem>
1094        </varlistentry>
1095        </variablelist>
1096      </appendix>
1097    
1098  </book>  </book>
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