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<!DOCTYPE book |
<!DOCTYPE book |
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PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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<!-- $ Revision: $ --> |
<!-- $Revision$ --> |
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<book> |
<book> |
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<bookinfo> |
<bookinfo> |
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<title>Thuban Manual</title> |
<title>Thuban Manual</title> |
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<author> |
<author> |
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<firstname></firstname><surname></surname> |
<firstname>Jonathan</firstname><surname>Coles</surname> |
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</author> |
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<author> |
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<firstname>Jan-Oliver</firstname><surname>Wagner</surname> |
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</author> |
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<author> |
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<firstname>Frank</firstname><surname>Koormann</surname> |
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</author> |
</author> |
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<copyright> |
<copyright> |
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<year>2003</year> |
<year>2003</year> |
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|
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<chapter><title>Introduction</title> |
<chapter><title>Introduction</title> |
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<para> |
<para> |
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Thuban is a Free Software Geographic Information Systems (GIS) viewer. |
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It is being developed because there is currently no simple interactive |
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viewer for geographic information available as Free Software. Thuban is |
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written in Python and C++ and uses the wxWindows library allowing it to |
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run on many different platforms, including GNU/Linux and Windows. |
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</para> |
</para> |
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<para> |
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GIS viewers are a necessary tool as they allow one to get a visual |
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impression of the positional relationship of the information that may not |
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be apparent from simple inspection of the data values themselves. |
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Thuban allows the user to create a session that displays |
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geographic data and then explore that data through navigation and |
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manipulation of how it is drawn. The results can then be saved or printed. |
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</para> |
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<para> |
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Thuban arranges a session in a hierarchy. A session contains a map which |
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consists of layers. Each layer represents one kind of data set. For |
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instance, there may be a layer for roads and another layer for buildings. |
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These layers can either be vector shapes or images. |
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</para> |
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|
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<section><title>Installation</title> |
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<para> |
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Thuban is actively supported under Debian Testing (sarge), RedHat 7.2, |
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and Windows 2000. All the necessary files can be found on the |
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<ulink url="http://thuban.intevation.org/download.html"> |
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Thuban Download site |
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</ulink>. |
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</para> |
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</section> |
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|
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<section><title>The Main Window</title> |
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<para> |
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<screenshot> |
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<screeninfo>The Main Window</screeninfo> |
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<mediaobject> |
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<imageobject> <imagedata fileref="../images/1_2_mainwindow.png" format="PNG"/> </imageobject> |
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<imageobject> <imagedata fileref="./images/1_2_mainwindow.ps" format="EPS"/> </imageobject> |
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<textobject><phrase>The Main Window</phrase></textobject> |
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<caption><para>The Main Window</para></caption> |
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</mediaobject> |
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</screenshot> |
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</para> |
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|
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<para> |
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The map window shows the current state of the map and is where |
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the user can interact with the map using the tools. |
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</para> |
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|
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<para> |
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The legend on the left displays a list of the current layers and |
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any visible classification groups. In the example, each shape layer |
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has a default classification which specifies how the shapes in each |
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layer are drawn. Layers that are higher in the list appear |
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``closer'' to the user. The legend can be closed by clicking on the |
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small X in the upper right-hand region of the legend. |
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To open it again, use |
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<menuchoice> |
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<guimenu>Map</guimenu> |
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<guimenuitem>Legend</guimenuitem> |
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</menuchoice>. |
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The legend is also dockable, which means that it can be detached |
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from the main window by clicking on the small button next to the |
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close button. It can be attached by clicking the same button |
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again. |
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</para> |
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<para> |
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The status bar displays different information depending on the |
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current context. If the user is selecting an item from the menu |
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then the status bar will display a short help message indicating |
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what each menu item is for. If the user has a tool selected then |
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the position of the cursor on the map is displayed. |
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</para> |
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<para> |
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The tool bar provides quick access to the commonly needed tools. |
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By hovering over each button the user can see a short messages |
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describing what the tool does. The tools provided are Zoom In, Zoom |
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Out, Pan, Full Extent, Full Layer Extent, Full Shape Extent, Indentify, |
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and Label. Each of the tools will be explained in further detail later |
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in the manual. |
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</para> |
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</section> |
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|
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</chapter> |
</chapter> |
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|
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<chapter><title>Session Management</title> |
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|
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<section><title>Starting a New Session</title> |
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<para> |
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A new session can be started from |
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<menuchoice> |
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<guimenu>File</guimenu> |
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<guimenuitem>New Session</guimenuitem> |
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</menuchoice>. |
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|
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If a session is already loaded and has been modified without |
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being saved a prompt will ask if the current session should |
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be saved. |
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|
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</para> |
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</section> |
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|
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<section><title>Opening a Session</title> |
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<para> |
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A session can be opened from |
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<menuchoice> |
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<guimenu>File</guimenu> |
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<guimenuitem>Open Session</guimenuitem> |
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</menuchoice>. |
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|
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If a session is already loaded and has been modified without |
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being saved a prompt will ask if the current session should |
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be saved. |
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</para> |
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</section> |
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|
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<section><title>Saving a Session</title> |
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<para> |
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A session can be saved from |
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<menuchoice> |
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<guimenu>File</guimenu> |
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<guimenuitem>Save Session</guimenuitem> |
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</menuchoice>. |
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|
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</para> |
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</section> |
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|
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<section><title>The Session Info-Tree</title> |
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<para> |
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(primarily for developers) |
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</para> |
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</section> |
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</chapter> |
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|
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<chapter><title>Map Management</title> |
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<para> |
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The map consists of a number of layers where each layer represents a |
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different type of data set. By interacting with the map the user can |
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visually explore the data. |
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</para> |
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|
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<section><title>Adding and Removing Layers</title> |
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<para> |
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There are two types of layers that can use added to a map: shape layers |
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and image layers. Shape layers are stored in Shapefile format, a |
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standard file format for storing geographic objects. Normally, these |
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files have the extension ``.shp''. Associated with |
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the object information is a database file which stores attributes for |
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each shape in the Shapefile. This file, stored in DB2 format, usually |
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has the extension ``.dbf''. Both files should have the same base name. |
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For example, if there is a Shapefile named roads.shp there should |
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also be a file roads.dbf. |
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</para> |
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<para> |
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Shape layers can be added to the map with |
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<menuchoice> |
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<guimenu>Map</guimenu> |
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<guimenuitem>Add Layer</guimenuitem> |
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</menuchoice>. |
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Thuban will load all files with the same base name, so it doesn't |
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matter if the Shapefile or database file is selected. |
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</para> |
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|
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<para> |
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Image layers can be added to the map with |
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<menuchoice> |
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<guimenu>Map</guimenu> |
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<guimenuitem>Add Image Layer</guimenuitem> |
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</menuchoice>. |
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It is important to select a valid image file that has geographic |
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data associated with it. This can be embedded in the file itself, |
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or in another file. If geographic information cannot be found, Thuban |
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will report an error. |
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</para> |
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</section> |
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|
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<section><title>Navigation</title> |
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<para> |
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The map can be explored by using the navigation tools available on |
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the tool bar, or from the |
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<menuchoice><guimenu>Map</guimenu></menuchoice> menu. |
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</para> |
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<para> |
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The ZoomIn tool |
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<inlinemediaobject> |
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<imageobject> |
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<imagedata fileref="../images/3_2_zoomin.png" format="PNG"/> |
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</imageobject> |
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<imageobject> |
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<imagedata fileref="./images/3_2_zoomin.eps" format="EPS"/> |
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</imageobject> |
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<textobject> <phrase>ZoomIn Tool</phrase> </textobject> |
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</inlinemediaobject> |
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can be used to enlarge a region of the map. Clicking once on the map |
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will double the magnification and center the map on the point that |
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was clicked. Clicking and dragging lets the user select a region |
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to be enlarged to fit the window. |
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</para> |
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<para> |
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The ZoomOut tool |
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<inlinemediaobject> |
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<imageobject> |
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<imagedata fileref="../images/3_2_zoomout.png" format="PNG"/> |
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</imageobject> |
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<imageobject> |
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<imagedata fileref="./images/3_2_zoomout.eps" format="EPS"/> |
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</imageobject> |
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<textobject> <phrase>ZoomOut Tool</phrase> </textobject> |
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</inlinemediaobject> |
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shrinks the map so that a larger region is visible. A single click |
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reduces the magnification by a factor of two. Clicking and dragging |
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selects a box such that the current contents of the window will be |
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scaled to fit into that box. |
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</para> |
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<para> |
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The Pan tool |
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<inlinemediaobject> |
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<imageobject> |
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<imagedata fileref="../images/3_2_pan.png" format="PNG"/> |
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</imageobject> |
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<imageobject> |
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<imagedata fileref="./images/3_2_pan.eps" format="EPS"/> |
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</imageobject> |
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<textobject> <phrase>Pan Tool</phrase> </textobject> |
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</inlinemediaobject> |
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allows the user to move the map around by clicking and dragging. |
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</para> |
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<para> |
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The Full Extent tool |
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<inlinemediaobject> |
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<imageobject> |
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<imagedata fileref="../images/3_2_fullextent.png" format="PNG"/> |
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</imageobject> |
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<imageobject> |
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<imagedata fileref="./images/3_2_fullextent.eps" format="EPS"/> |
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</imageobject> |
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<textobject> <phrase>Full Extent Tool</phrase> </textobject> |
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</inlinemediaobject> |
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rescales the viewable region so that the entire map is visible. |
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</para> |
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<para> |
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The Full Layer Extent tool |
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<inlinemediaobject> |
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<imageobject> |
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<imagedata fileref="../images/3_2_fulllayerextent.png" format="PNG"/> |
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</imageobject> |
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<imageobject> |
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<imagedata fileref="./images/3_2_fulllayerextent.eps" format="EPS"/> |
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</imageobject> |
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<textobject> <phrase>Full Layer Extent Tool</phrase> </textobject> |
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</inlinemediaobject> |
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rescales the viewable region so that the currently selected |
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layer fits within the window. If no layer is selected this button |
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will be disabled. |
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</para> |
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<para> |
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The Full Shape Extent tool |
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<inlinemediaobject> |
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<imageobject> |
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<imagedata fileref="../images/3_2_fullshapeextent.png" format="PNG"/> |
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</imageobject> |
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<imageobject> |
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<imagedata fileref="./images/3_2_fullshapeextent.eps" format="EPS"/> |
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</imageobject> |
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<textobject> <phrase>Full Shape Extent Tool</phrase> </textobject> |
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</inlinemediaobject> |
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rescales the viewable region so that the currently selected |
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shape fits within the window. If the shape is a point, it is |
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centered and the map is zoomed all the way in. If no shape is |
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selected this button will be disabled. |
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</para> |
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</section> |
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|
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<section><title>Object Identification</title> |
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<para> |
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Objects on the map can be identified using the Identify tool |
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<inlinemediaobject> |
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<imageobject> |
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<imagedata fileref="../images/3_3_identify.png" format="PNG"/> |
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</imageobject> |
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<imageobject> |
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<imagedata fileref="./images/3_3_identify.eps" format="EPS"/> |
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</imageobject> |
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<textobject> <phrase>Identify Tool</phrase> </textobject> |
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</inlinemediaobject>. |
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Clicking on an object selects that object and opens a dialog which |
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shows all the table attributes for that object. Any current selection |
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is lost. |
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</para> |
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</section> |
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|
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<section><title>Object Labelling</title> |
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|
<para> |
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|
Objects can be labelled using the Label tool |
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<inlinemediaobject> |
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<imageobject> |
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<imagedata fileref="../images/3_3_label.png" format="PNG"/> |
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</imageobject> |
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<imageobject> |
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<imagedata fileref="./images/3_3_label.eps" format="EPS"/> |
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</imageobject> |
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<textobject> <phrase>Label Tool</phrase> </textobject> |
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</inlinemediaobject>. |
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Clicking on an object selects that object and opens a dialog which |
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displays the table attributes for that object. An attribute can |
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be selected to be the label on the map. Using this tool for an |
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object that already has a label will remove the label. |
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|
</para> |
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|
</section> |
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|
|
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|
<section><title>The Legend</title> |
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|
<para> |
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|
The Legend provides an overview of the layers in the map. Layers |
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that appear higher in the legend will appear ``closer'' to the user. |
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If a layer supports classification (currently, only shape layers |
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|
have this feature) then the classification groups will be shown |
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|
below each layer. The properties for each group are also displayed |
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|
with a small graphic. Polygon layers appear as rectangles, lines |
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appear as curved lines, and points appear as circles. |
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|
</para> |
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|
<para> |
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|
Along the top of the legend is a toolbar which allows quick access |
| 348 |
|
to some of the layer manipulation options under |
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|
<menuchoice> <guimenu>Map</guimenu> </menuchoice>. |
| 350 |
|
|
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|
Double-clicking on a layer or a group of a layer will open the |
| 352 |
|
properties dialog for that layer. |
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|
</para> |
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|
</section> |
| 355 |
|
|
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|
<section><title>Printing</title> |
| 357 |
|
<para> |
| 358 |
|
The map can be printed using |
| 359 |
|
<menuchoice> |
| 360 |
|
<guimenu>Map</guimenu> |
| 361 |
|
<guimenuitem>Print</guimenuitem> |
| 362 |
|
</menuchoice>. A standard printing dialog will open allowing the |
| 363 |
|
user to configure the printer. |
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|
</para> |
| 365 |
|
</section> |
| 366 |
|
</chapter> |
| 367 |
|
|
| 368 |
|
<chapter><title>Layer Management</title> |
| 369 |
|
<para> |
| 370 |
|
</para> |
| 371 |
|
|
| 372 |
|
<section><title>Types of Layers</title> |
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|
<para> |
| 374 |
|
There are two types of layers supported by Thuban: shape layers and |
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|
image layers. Shape layers consist of vector based shapes with |
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|
geo-referenced coordinates. There are three types of supported |
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|
shapes: polygons, lines, and points. Image layers can be any image |
| 378 |
|
file format supported by GDAL. The images must have geographic |
| 379 |
|
coordinate data either embedded within the file, or in a seperate |
| 380 |
|
file that is in the same directory as the image file. GeoTIFF files |
| 381 |
|
work very well with Thuban and were designed specifically to be image |
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|
layers in GIS programs. |
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|
</para> |
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|
</section> |
| 385 |
|
|
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|
<section><title>Properties</title> |
| 387 |
|
<para> |
| 388 |
|
Each shape in a shape layer can have various properties which control |
| 389 |
|
how it is drawn on the map. Polygons and points can be drawn with an |
| 390 |
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outline color and a fill color, while lines have only a line color. |
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|
</para> |
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|
</section> |
| 393 |
|
|
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|
<section><title>Visibility</title> |
| 395 |
|
<para> |
| 396 |
|
Sometimes it is not desirable to view all layers at the same time. |
| 397 |
|
Some layers may take a long time to draw and so while navigating |
| 398 |
|
around the map the user may not want to wait for the map to redraw |
| 399 |
|
each time the map is changed. Each layer can be independently |
| 400 |
|
turned on or off using the |
| 401 |
|
<menuchoice> |
| 402 |
|
<guimenu>Layer</guimenu> |
| 403 |
|
<guimenuitem>Show</guimenuitem> |
| 404 |
|
</menuchoice> |
| 405 |
|
or |
| 406 |
|
<menuchoice> |
| 407 |
|
<guimenu>Layer</guimenu> |
| 408 |
|
<guimenuitem>Hide</guimenuitem> |
| 409 |
|
</menuchoice> options respectively. |
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|
</para> |
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|
</section> |
| 412 |
|
|
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|
<section><title>Sequence</title> |
| 414 |
|
<para> |
| 415 |
|
</para> |
| 416 |
|
</section> |
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|
|
| 418 |
|
<section><title>Duplication</title> |
| 419 |
|
<para> |
| 420 |
|
Layers and all their properties, including classifications, can |
| 421 |
|
be duplicated using |
| 422 |
|
<menuchoice> |
| 423 |
|
<guimenu>Layer</guimenu> |
| 424 |
|
<guimenuitem>Duplicate</guimenuitem> |
| 425 |
|
</menuchoice>. Duplicating a layer is useful if the user wishes |
| 426 |
|
to model a layer in several different ways. Even though the layers |
| 427 |
|
overlap by carefully selecting the shape properties it is possible |
| 428 |
|
to display several pieces of information at once. For example, one |
| 429 |
|
copy of a roads layer may be classified on a length property and |
| 430 |
|
another copy may be classified on a type property. if the length |
| 431 |
|
property was expressed with color and the type property expressed |
| 432 |
|
with line thickness then it would be possible to view both |
| 433 |
|
classifications by placing the type property copy over the |
| 434 |
|
length property copy. |
| 435 |
|
</para> |
| 436 |
|
</section> |
| 437 |
|
|
| 438 |
|
</chapter> |
| 439 |
|
|
| 440 |
|
<chapter><title>Layer Classifications</title> |
| 441 |
|
<para> |
| 442 |
|
A layer classification is a way of assigning drawing properties to |
| 443 |
|
groups of shapes based on attributes stored in the layer's table. |
| 444 |
|
Only layer's with shapes can have a classification; image layers |
| 445 |
|
cannot be classified. |
| 446 |
|
</para> |
| 447 |
|
<para> |
| 448 |
|
A classification consists of a number of groups, with each group |
| 449 |
|
having a value or range of values to match against, and symbol |
| 450 |
|
properties which control how a shape is drawn on the map. The user |
| 451 |
|
selects which field in the table is used by the classification and |
| 452 |
|
when the map is drawn the value for that field for each shape is |
| 453 |
|
compared with each group's value. The properties of the first group |
| 454 |
|
to match are used to draw the shape. This allows the user to get a |
| 455 |
|
visual impression of not only how the data is laid out but also what |
| 456 |
|
kind of data lies where. |
| 457 |
|
</para> |
| 458 |
|
<para> |
| 459 |
|
A layer always has a classification. When a new layer is added to the |
| 460 |
|
map, a default classification is created with the DEFAULT group. This |
| 461 |
|
group cannot be removed. Every shape in the layer, regardless of its |
| 462 |
|
attributes, will match this group. |
| 463 |
|
</para> |
| 464 |
|
|
| 465 |
|
<section><title>Editing Classifications</title> |
| 466 |
|
<para> |
| 467 |
|
A layer's classification can be modified under the properties dialog |
| 468 |
|
(<menuchoice> |
| 469 |
|
<guimenu>Layer</guimenu> |
| 470 |
|
<guimenuitem>Properties</guimenuitem> |
| 471 |
|
</menuchoice>). The layer's classification field can be set to None, |
| 472 |
|
which simply assigns a DEFAULT group to the classification. No new |
| 473 |
|
groups can be added to the classification if the field is None. |
| 474 |
|
The user must first select a field to classify on. New groups can |
| 475 |
|
be added to the classification with the <guibutton>Add</guibutton> |
| 476 |
|
button. |
| 477 |
|
</para> |
| 478 |
|
<para> |
| 479 |
|
The order of the groups in the classification is significant |
| 480 |
|
except for the DEFAULT group, which remains at the top. When shapes |
| 481 |
|
are matched against groups the matching begins at the first group |
| 482 |
|
other than the DEFAULT group so that groups higher in the list will |
| 483 |
|
be checked first. Matching for a |
| 484 |
|
given shape will stop at the first group that matches. The user can |
| 485 |
|
use <guibutton>Move Up</guibutton> and <guibutton>Move Down</guibutton> |
| 486 |
|
to change the order of the groups. The DEFAULT group will always |
| 487 |
|
match a shape that hasn't matched another group. |
| 488 |
|
</para> |
| 489 |
|
<para> |
| 490 |
|
The Value column of the classification table is the value that will |
| 491 |
|
be matched when the map is being drawn. The type of data that can |
| 492 |
|
entered into this field depends on the type of data of the |
| 493 |
|
classification field. |
| 494 |
|
</para> |
| 495 |
|
<para> |
| 496 |
|
If the field is of type Text, anything entered |
| 497 |
|
into the field is valid. The text will be compared literally to the |
| 498 |
|
value of the shape attribute, including case sensitivity. |
| 499 |
|
If the type is Integer, then any valid integer may be entered. In |
| 500 |
|
addition, with special syntax, a range of values can be entered. |
| 501 |
|
A range from <varname>start</varname> to <varname>end</varname> |
| 502 |
|
inclusive is specifed like this: <literal>[start;end]</literal>. |
| 503 |
|
The exclusive range is specified like this: |
| 504 |
|
<literal>]start;end[</literal>. Ranges can include infinity like |
| 505 |
|
this: <literal>[-oo;oo]</literal>. Field types can also be of type |
| 506 |
|
Decimal. They represent any rational number and can be used in ranges |
| 507 |
|
as well. |
| 508 |
|
</para> |
| 509 |
|
</section> |
| 510 |
|
|
| 511 |
|
<section><title>Symbols</title> |
| 512 |
|
<para> |
| 513 |
|
Each type of shape has its own type of symbol. Thuban supports three |
| 514 |
|
types of shapes: polygons, lines, and points. Polygons and points have |
| 515 |
|
outline and fill color, while lines have only line color. Each group |
| 516 |
|
has associated symbol properties. To edit the symbol properties for a |
| 517 |
|
group the user can double click on the Symbol column or select a |
| 518 |
|
group and click the <guibutton>Edit Symbol</guibutton> button. |
| 519 |
|
</para> |
| 520 |
|
</section> |
| 521 |
|
|
| 522 |
|
<section><title>Generating Classes</title> |
| 523 |
|
<para> |
| 524 |
|
Creating a classification by hand can be tedious. |
| 525 |
|
Thuban, therefore, provides a means of generating an entire |
| 526 |
|
classification at once while still giving the user control over |
| 527 |
|
how it appears. Clicking <guibutton>Generate Class</guibutton> |
| 528 |
|
opens the <varname>Generate Classification</varname> dialog. |
| 529 |
|
Under the <varname>Generate</varname> pulldown there are at most |
| 530 |
|
three different ways to generate classifications: |
| 531 |
|
Unique Values, Unique Distribution, and Quantiles. Some options |
| 532 |
|
may not be available if they data type for the field does not |
| 533 |
|
support them. For instance, <varname>Unique Distribution</varname> |
| 534 |
|
doesn't make sense for a Text field. |
| 535 |
|
</para> |
| 536 |
|
<para> |
| 537 |
|
For every way of generating a classification, a color scheme must |
| 538 |
|
be selected. Thuban provides several different color schemes that |
| 539 |
|
affect how the group properties change over the classification. |
| 540 |
|
It is also possible to create a custom color scheme. Selecting |
| 541 |
|
this option will display two symbols: the one of the left has the |
| 542 |
|
properties of the first group and the one on the right has the |
| 543 |
|
properties of the last group. Thuban will interpolate between these |
| 544 |
|
two properties to generate the other groups. |
| 545 |
|
</para> |
| 546 |
|
<para> |
| 547 |
|
The Unique Values option lets the user select specific values that |
| 548 |
|
appear in the table. Clicking <guibutton>Retrieve From Table</guibutton> |
| 549 |
|
searches the table for all unique values and displays them in the |
| 550 |
|
list on the left. Items can be selected and moved to the list on the |
| 551 |
|
right. Each list can be sorted or reversed for easier searching. |
| 552 |
|
The classification that is generated will be in the same order as |
| 553 |
|
the list on the right. |
| 554 |
|
</para> |
| 555 |
|
<para> |
| 556 |
|
The Unique Distribution option creates a user specified number of |
| 557 |
|
groups of ranges such that each range covers equal intervals. The |
| 558 |
|
minimum and maximum values can automatically be retrieved from the |
| 559 |
|
table by clicking <guibutton>Retrieve From Table</guibutton>. The |
| 560 |
|
stepping is how large each interval is. Adjusting this value will |
| 561 |
|
automatically recalculate how many groups is appropriate. |
| 562 |
|
</para> |
| 563 |
|
<para> |
| 564 |
|
The Quantiles option generates ranges based on the number items |
| 565 |
|
in the input set. For example, by specifying 5 groups Thuban will |
| 566 |
|
generate groups with appropriate ranges such that 20% of the table |
| 567 |
|
data is in each group. If it is impossible to generate exact |
| 568 |
|
grouping, Thuban will issue a warning but allow the user to continue. |
| 569 |
|
</para> |
| 570 |
|
</section> |
| 571 |
|
</chapter> |
| 572 |
|
|
| 573 |
|
<chapter><title>Projection Management</title> |
| 574 |
|
<para> |
| 575 |
|
Projections control how the geographic data is displayed on the screen. |
| 576 |
|
If multiple layers are loaded into Thuban where the geographic data |
| 577 |
|
is in a different projection system, then the user must tell Thuban |
| 578 |
|
which projection each layer has. The user must also tell Thuban which |
| 579 |
|
projection the map is in. This can be the same as the layers or a different |
| 580 |
|
projection in which case the layers are reprojected into that space. |
| 581 |
|
The map projection can be set using |
| 582 |
|
<menuchoice> |
| 583 |
|
<guimenu>Map</guimenu> |
| 584 |
|
<guimenuitem>Projection</guimenuitem> |
| 585 |
|
</menuchoice> and the layer projection can be set using |
| 586 |
|
<menuchoice> |
| 587 |
|
<guimenu>Layer</guimenu> |
| 588 |
|
<guimenuitem>Projection</guimenuitem> |
| 589 |
|
</menuchoice>. |
| 590 |
|
</para> |
| 591 |
|
<para> |
| 592 |
|
Thuban is distributed with a sample collection of projections. The |
| 593 |
|
user can create new projections and make them available to all |
| 594 |
|
future Thuban sessions. They may also be exported and imported so |
| 595 |
|
that custom projections can be distributed to others. |
| 596 |
|
</para> |
| 597 |
|
<section><title>Selecting a Projection</title> |
| 598 |
|
<para> |
| 599 |
|
The available projections are listed on the left. If the layer |
| 600 |
|
or map already has a projection it will be initially highlighted |
| 601 |
|
and will end with <varname>(current)</varname>. Selecting |
| 602 |
|
<varname>None</varname> will cause Thuban to use the data as |
| 603 |
|
it appears in the source file and will not use a projection. |
| 604 |
|
</para> |
| 605 |
|
</section> |
| 606 |
|
<section><title>Editing a Projection</title> |
| 607 |
|
<para> |
| 608 |
|
Whenever a projection is selected from the list its properties |
| 609 |
|
are displayed on the right. These properties can be changed |
| 610 |
|
and the changes saved to the selected projection using |
| 611 |
|
the <guibutton>Update</guibutton>. Only a projection that comes |
| 612 |
|
from a file can be updated, so if the current layer's projection |
| 613 |
|
is selectd, <guibutton>Update</guibutton> will be disabled. |
| 614 |
|
The <guibutton>Add to List</guibutton> adds the projection to the |
| 615 |
|
list of available projections as a new entry, and thus make it |
| 616 |
|
available to future Thuban sessions. Clicking <guibutton>New</guibutton> |
| 617 |
|
will create an entirely new, empty projection. The |
| 618 |
|
<guibutton>Remove</guibutton> button will permanantly remove a |
| 619 |
|
projection from the list of available projections. |
| 620 |
|
</para> |
| 621 |
|
</section> |
| 622 |
|
<section><title>Importing/Exporting Projections</title> |
| 623 |
|
<para> |
| 624 |
|
The projections that appear in the list of available projections |
| 625 |
|
can be exported to another file that the user chooses. By selecting |
| 626 |
|
one or more projections and clicking <guibutton>Export</guibutton> |
| 627 |
|
the user will be able to select a file to store those projections. |
| 628 |
|
The file can then be distributed to other Thuban users. To import |
| 629 |
|
a projection file the user can click <guibutton>Import</guibutton>. |
| 630 |
|
The imported projections are added to the list and are then available |
| 631 |
|
to the current session and any future Thuban session. |
| 632 |
|
</para> |
| 633 |
|
</section> |
| 634 |
|
</chapter> |
| 635 |
|
|
| 636 |
|
<chapter><title>Table Management</title> |
| 637 |
|
<para> |
| 638 |
|
Thuban distinguishes two different types of tables: Attribute tables |
| 639 |
|
(which belong to a layer) and usual data tables. Both provide in |
| 640 |
|
general the same functionality with the difference that actions on an |
| 641 |
|
attribute table might also effect the map display. |
| 642 |
|
</para> |
| 643 |
|
|
| 644 |
|
<section><title>Table View</title> |
| 645 |
|
<para> |
| 646 |
|
Thuban provides a standard dialog to display table contents, the |
| 647 |
|
Table View. The view falls into five sections: The title, selections, |
| 648 |
|
the table grid, export functions and the status bar. |
| 649 |
|
</para> |
| 650 |
|
<para> |
| 651 |
|
The title bar identifies the table with it's name. |
| 652 |
|
</para> |
| 653 |
|
<para> |
| 654 |
|
The functions box let the user perform simple analysis on the data |
| 655 |
|
based on comparisons: First choice must be a field identifier of the |
| 656 |
|
table, the second choice determines the type of comparison. The third |
| 657 |
|
choice can be either a specific value (interpreted as numerical |
| 658 |
|
or string depending on the type of the first field) or a second field |
| 659 |
|
identifier. Thus you can perform analysis like selecting all |
| 660 |
|
records where "population > 10000" or |
| 661 |
|
"cars_per_habitants < bike_per_habitants" (note that the field names |
| 662 |
|
are only explanatory, the currently considered dbase files allow only |
| 663 |
|
11 character field names). |
| 664 |
|
|
| 665 |
|
Selections can be combined, either by applying a selection only on |
| 666 |
|
a previously selected set of records or by adding the results of a |
| 667 |
|
selection to a previous set. The default is that a selection replaces |
| 668 |
|
earlier results. |
| 669 |
|
</para> |
| 670 |
|
<para> |
| 671 |
|
The table grid shows the contents of the table (a record per column), |
| 672 |
|
with highlighted selection results. Columns and rows can be resized. |
| 673 |
|
</para> |
| 674 |
|
<para> |
| 675 |
|
The contents of a table can be exported into a file, either dbase |
| 676 |
|
format (DBF) or comma seperated values (CSV). The 'Export' button |
| 677 |
|
raises a file dialog to specify a path and file name, the export type |
| 678 |
|
is determined by the file extension (either .dbf or .csv). |
| 679 |
|
|
| 680 |
|
The 'Export Selection' button works similar but exports only the |
| 681 |
|
selected records. |
| 682 |
|
|
| 683 |
|
The 'Close' button closes the table view. In difference to the |
| 684 |
|
menu item 'Close' just the dialog is closed, the table is still loaded |
| 685 |
|
in Thuban. |
| 686 |
|
</para> |
| 687 |
|
<para> |
| 688 |
|
The status bar displays some statistics about the table and optional |
| 689 |
|
selection results. |
| 690 |
|
</para> |
| 691 |
|
</section> |
| 692 |
|
|
| 693 |
|
<section><title>General Functionality (Menu Table)</title> |
| 694 |
|
<para> |
| 695 |
|
The general functions affect all tables open in Thuban. Attribute |
| 696 |
|
tables are considered as here as usual data tables (with the exception |
| 697 |
|
that they cannot be closed). |
| 698 |
|
</para> |
| 699 |
|
<section><title>Open</title> |
| 700 |
|
<para> |
| 701 |
|
The 'Open' item raises a file dialog to let you select a |
| 702 |
|
dbase file from the file system to be loaded into Thuban read-only. |
| 703 |
|
On OK the selected file is loaded and a table view is opened. |
| 704 |
|
</para> |
| 705 |
|
</section> |
| 706 |
|
|
| 707 |
|
<section><title>Close</title> |
| 708 |
|
<para> |
| 709 |
|
The 'Close' item raises a dialog listing the currently open |
| 710 |
|
data tables (loaded via the 'Open' functionality'). You can select |
| 711 |
|
tables which are dereferenced on confirmation. Since tables are |
| 712 |
|
opened read-only the contents of the tables are not affected. |
| 713 |
|
|
| 714 |
|
A still open table view is closed as well. |
| 715 |
|
|
| 716 |
|
Tables used in a join can not be closed. |
| 717 |
|
</para> |
| 718 |
|
</section> |
| 719 |
|
|
| 720 |
|
<section><title>Rename</title> |
| 721 |
|
<para> |
| 722 |
|
Changes the table title. |
| 723 |
|
</para> |
| 724 |
|
</section> |
| 725 |
|
|
| 726 |
|
<section><title>Show</title> |
| 727 |
|
<para> |
| 728 |
|
The 'Show' item raises a list of available tables (explicitly loaded, attribute tables, results of a join). Selected tables are show in |
| 729 |
|
tables views on 'OK'. |
| 730 |
|
</para> |
| 731 |
|
</section> |
| 732 |
|
|
| 733 |
|
<section><title>Join</title> |
| 734 |
|
<para> |
| 735 |
|
The 'Join' item raises a dialog to specify the two tables to be |
| 736 |
|
joined. The join results in a new table named 'Join of "left table" |
| 737 |
|
and "right table"'. |
| 738 |
|
|
| 739 |
|
The dialog let you select the two tables to be joined and the two |
| 740 |
|
fields the join has to be performed on. By default the new |
| 741 |
|
table contains only those records which are mathced by the join. |
| 742 |
|
|
| 743 |
|
If you want to preserve the records of the left table you can perform |
| 744 |
|
an outer join. The fields from the right table for records not |
| 745 |
|
matched by the join are filled with <varname>None</varname> in this |
| 746 |
|
case. |
| 747 |
|
</para> |
| 748 |
|
</section> |
| 749 |
|
|
| 750 |
|
</section> |
| 751 |
|
<section><title>Attribute Tables</title> |
| 752 |
|
<para> |
| 753 |
|
To clearly separate between both types, Thuban provides functionality |
| 754 |
|
regarding the attribute tables under the Layer menu. |
| 755 |
|
</para> |
| 756 |
|
|
| 757 |
|
<section><title>Show Table</title> |
| 758 |
|
<para> |
| 759 |
|
Opens the attribute table of the currently active layer in a table |
| 760 |
|
view. |
| 761 |
|
|
| 762 |
|
In addition to the functionality described above selections |
| 763 |
|
affect also the map display: objects related to selected records |
| 764 |
|
are highlighted. |
| 765 |
|
</para> |
| 766 |
|
</section> |
| 767 |
|
|
| 768 |
|
<section><title>Join Table</title> |
| 769 |
|
<para> |
| 770 |
|
In difference to the join described above the join results not in a |
| 771 |
|
new table. The attribute table of the currently active layer is the |
| 772 |
|
left table and other tables are join to this table. Results of the |
| 773 |
|
join in turn are available for classifications. |
| 774 |
|
|
| 775 |
|
As a consequence of the above the join cannot result in less |
| 776 |
|
records than the source attribute table. You are warned if the |
| 777 |
|
right table does not fulfill this constraint. Use an outer join |
| 778 |
|
in such cases. |
| 779 |
|
</para> |
| 780 |
|
</section> |
| 781 |
|
|
| 782 |
|
<section><title>Unjoin Table</title> |
| 783 |
|
<para> |
| 784 |
|
As said above, a usual table can not be closed while still used in |
| 785 |
|
a join. While the join table resulting from a join of usual tables |
| 786 |
|
can be simply closed (and therewith dereferences the source tables) |
| 787 |
|
this is not possible for attribute tables. |
| 788 |
|
|
| 789 |
|
Hence joins on attribute tables must be solved explicitely. This is |
| 790 |
|
what the 'Unjoin' item is used for: The last join for the currently |
| 791 |
|
active layer is solved. |
| 792 |
|
</para> |
| 793 |
|
</section> |
| 794 |
|
|
| 795 |
|
</section> |
| 796 |
|
</chapter> |
| 797 |
|
|
| 798 |
|
<chapter><title>Trouble Shooting</title> |
| 799 |
|
<para> |
| 800 |
|
</para> |
| 801 |
|
</chapter> |
| 802 |
|
|
| 803 |
|
<appendix><title>Supported Data Sources</title> |
| 804 |
|
<para> |
| 805 |
|
</para> |
| 806 |
|
<variablelist> |
| 807 |
|
<varlistentry> |
| 808 |
|
<term>Shapefile</term> |
| 809 |
|
<listitem><para></para></listitem> |
| 810 |
|
</varlistentry> |
| 811 |
|
|
| 812 |
|
<varlistentry> |
| 813 |
|
<term>DB2 file</term> |
| 814 |
|
<listitem><para></para></listitem> |
| 815 |
|
</varlistentry> |
| 816 |
|
|
| 817 |
|
</variablelist> |
| 818 |
|
</appendix> |
| 819 |
|
|
| 820 |
|
<appendix><title>Supported Projections</title> |
| 821 |
|
<para> |
| 822 |
|
</para> |
| 823 |
|
<variablelist> |
| 824 |
|
<varlistentry> |
| 825 |
|
<term>Geographic</term> |
| 826 |
|
<listitem><para>Geographic</para></listitem> |
| 827 |
|
</varlistentry> |
| 828 |
|
<varlistentry> |
| 829 |
|
<term>Lambert Conic Conformal</term> |
| 830 |
|
<listitem><para>Lambert Conic Conformal</para></listitem> |
| 831 |
|
</varlistentry> |
| 832 |
|
<varlistentry> |
| 833 |
|
<term>Transverse Mercator</term> |
| 834 |
|
<listitem><para>Transverse Mercator</para></listitem> |
| 835 |
|
</varlistentry> |
| 836 |
|
<varlistentry> |
| 837 |
|
<term>Universal Transverse Mercator</term> |
| 838 |
|
<listitem><para>Universal Transverse Mercator</para></listitem> |
| 839 |
|
</varlistentry> |
| 840 |
|
</variablelist> |
| 841 |
|
</appendix> |
| 842 |
|
|
| 843 |
</book> |
</book> |
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Revision Log
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