Geografic-Information-System/gui/wxpython/docs/wxGUI.Vector_Digitizer.html

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<h2>DESCRIPTION</h2>

The <b>Vector digitizer</b> is
a <em><a href="wxGUI.html">wxGUI</a></em> component intended for
interactive editing vector maps
(see <em><a href="v.edit.html">v.edit</a></em> for non-interactive
vector editing GRASS capabilities).

<p>
Currently, only 2D vector features (points, lines, centroids and
boundaries) can be edited.

Vector features can be selected using mouse or by query (e.g. minimal
vector line length). Vector features can be selected by bounding box
or simply by mouse click (based on 'Settings-&gt;General-&gt;Select
threshold' value).

<p>
Vector digitizer can be activated from Main toolbar in Map Display by
selecting "Digitize" from "Tools" combobox. Vector map to be edited
can be afterwards selected from digitizer toolbar ("Select vector map"
combobox, note that only vector maps from the current layer tree in Layer
Manager are available).

Vector digitizer can be alternatively also activated from contextual
menu in Layer Manager by selecting "Start editing" on selected vector
map in the layer tree.

<p>
New vector map can be easily created from digitizer toolbar by
selecting "New vector map" in "Select vector map" combobox. A new
vector map is created, added to the current layer tree in Layer
Manager and opened for editing. "Select vector map" combobox in
digitizer toolbar also allows switching easily between vector maps to be
edited.
<p>
The wxGUI vector digitizer draws all maps in the Layer Manager in the Map 
Display window; in addition, the digitizer also recognizes a special 
"background" vector map. This map is selected from the Layer Manager by 
right-clicking on the map and selecting "Use as Background Map" from the
contextual menu. The features of the background map may then be copied into
the currently edited vector map using the "Copy features from (background) 
vector map" button in the "Additional Tools" menu on the Digitzer Toolbar.

<h3>DIGITIZER TOOLBAR</h3>

<center>
<br><img src="wxGUI_vector_digitizer_toolbar.jpg" border="1"><br><br>
</center>

<dl>
  <dt><img src="icons/point-create.png">&nbsp;
    <em>Digitize new point</em></dt>
  <dd>Add new point to vector map and optionally define its
    attributes.</dd>
  
  <dt><img src="icons/line-create.png">&nbsp;
    <em>Digitize new line</em></dt>
  <dd>Add new line to vector map and optionally define its
    attributes.</dd>

  <dt><img src="icons/polygon-create.png">&nbsp;
    <em>Digitize new boundary</em></dt>
  <dd>Add new boundary to vector map and optionally define its
    attributes.</dd>
  
  <dt><img src="icons/centroid-create.png">&nbsp;
    <em>Digitize new centroid</em></dt>
  <dd>Add new centroid to vector map and optionally define its
    attributes.</dd>
  
  <dt><img src="icons/vertex-move.png">&nbsp;
    <em>Move vertex</em></dt>
  <dd>Move selected vertex of linear feature. Thus shape of linear
    feature is changed.</dd>

  <dt><img src="icons/vertex-create.png">&nbsp;
    <em>Add vertex</em></dt>
  <dd>Add new vertex to selected linear feature (shape not
    changed).</dd>

  <dt><img src="icons/vertex-delete.png">&nbsp;
    <em>Remove vertex</em></dt>
  <dd>Remove selected vertex from linear feature. Thus shape of selected
  feature can be changed.</dd>

  <dt><img src="icons/line-split.png">&nbsp;
    <em>Split line/boundary</em></dt>
  <dd>Split selected linear feature on given position to separate
  vector features.</dd>

  <dt><img src="icons/line-edit.png">&nbsp;
    <em>Edit line/boundary</em></dt>
  <dd>Edit selected linear feature, add new segments or remove
  existing segments of linear feature.</dd>

  <dt><img src="icons/line-move.png">&nbsp;
    <em>Move feature(s)</em></dt>
  <dd>Move selected vector features. Selection can be done by mouse or
    by query.</dd>

  <dt><img src="icons/line-delete.png">&nbsp;
    <em>Delete feature(s)</em></dt>
  <dd>Delete selected vector features. Selection can be done by mouse
  or by query.</dd>

  <dt><img src="icons/cats-display.png">&nbsp;
    <em>Display/update categories</em></dt>
  <dd>Display categories of selected vector feature. Category settings
  can be modified, new layer/category pairs added or already defined pairs
  removed.</dd>

  <dt><img src="icons/cats-copy.png">&nbsp;
    <em>Copy categories / Duplicate attributes</em></dt>
  <dd><ul>
      <li>Copy category settings of selected vector feature to other
	vector features. Layer/category pairs of source vector features are
	appended to the target feature category settings. Existing
	layer/category pairs are not removed from category settings of the
	target features.</li>
      <li>Duplicate attributes settings of selected vector feature to
	other vector features. New category(ies) is appended to the
	target feature category settings and attributes duplicated
	based on category settings of source vector features. Existing
	layer/category pairs are not removed from category settings of
	the target features.</li>
    </ul>
  </dd>

  <dt><img src="icons/attributes-display.png">&nbsp;
    <em>Display/update attributes</em></dt>
  <dd>Display attributes of selected vector feature (based on its
    category settings).  Attributes can be also modified. Same
    functionality is accessible from Main toolbar "Query vector map
    (editable mode)".</dd>

  <dt><img src="icons/tools.png">&nbsp;
    <em>Additional tools</em></dt>
  <dd>
    <ul>
      <li>Copy features from (background) map<br> Make identical copy of
	selected vector features. If a background vector map has been 
	selected from the Layer Manager, copy features from background 
	vector map, not from the currently modified vector map.</li>
      <li>Flip selected lines/boundaries<br> Flip direction of
	selected linear features (lines or boundaries).</li>
      <li>Merge selected lines/boundaries<br> Merge (at least two)
	selected vector lines or boundaries. The geometry of the
	merged vector lines can be changed. If the second line from
	two selected lines is in opposite direction to the first, it
	will be flipped. See also
	module <em><a href="v.build.polylines.html">v.build.polylines</a></em>.</li>
      <li>Break selected lines/boundaries at intersection<br> Split
	given vector line or boundary into two lines on given position
	(based on <em><a href="v.clean.html">v.clean</a></em>,
	tool=break).</li>
      <li>Snap selected lines/boundaries (only to nodes)<br> Snap
	vector features in given threshold. See also
	module <em><a href="v.clean.html">v.clean</a></em>. Note that
	this tool supports only snapping to nodes. Snapping to vector
	features from background vector map is not currently
	supported.</li>
      <li>Connect two selected lines/boundaries<br> Connect selected
	lines or boundaries, the first given line is connected to the
	second one. The second line is broken if necessary on each intersection.
	The lines are connected only if distance between them is not greater
	than snapping threshold value.</li>
      <li>Query tool<br>Select vector features by defining a threshold for
        min/max length value (linear features or dangles).</li>
      <li>Z-bulk labeling of 3D lines<br> Assign z coordinate values to 3D
	vector lines in bounding box. This is useful for labeling contour lines.</li>
      <li>Feature type conversion<br> Change feature type of selected
	geometry features. Points are converted to centroids,
	centroids to points, lines to boundaries and boundaries to
	lines.</li>
    </ul>
  </dd>

  <dt><img src="icons/undo.png">&nbsp;
    <em>Undo</em></dt>
  <dd>Undo previous operations.</dd>

  <dt><img src="icons/settings.png">&nbsp;
    <em>Settings</em></dt>
  <dd>Dialog for vector digitizer settings.</dd>

  <dt><img src="icons/quit.png">&nbsp;
    <em>Quit digitizing tool</em></dt>
  <dd>Changes in vector map can be optionally discarded when
  digitizing session is quited.</dd>

</dl>

<h2>NOTES</h2>

<dl><dt><b>Mouse button Functions:</b><dd>
	<dt><i>Left</i>   - select/deselect features</dt>
	<dt><i>Control+Left</i> - cancel action/undo vertex</dt>
	<dt><i>Right</i>  - confirm action</dt>
</dl>

<p>
<i>Dead (deleted)</i> are internally only marked in the geometry file
as 'dead' but it remains there and occupies space. Any vector module
used afterwards on this vector map which really reads and writes
vector geometry (so not <em><a href="g.copy.html">g.copy</a></em>)
will writes only features which are 'alive'.

<p>
<i>Added or modified</i> vector features are <i>snapped</i> to
existing vector features ('Settings-&gt;General-&gt;Snapping', nodes or vertices)
based on 'Settings-&gt;General-&gt;Snapping threshold' value. To
disable snapping set the snapping threshold to '0'.

<p>
If the digitizer crashes for some reason you can repair the vector map
which was left open with
the <em><a href="v.build.html">v.build</a></em> module.

<h2>SEE ALSO</h2>

<em>
  <a href="wxGUI.html">wxGUI</a>
</em>

<p>
Other wxGUI components:<br>
<em>
  <a href="wxGUI.Attribute_Table_Manager.html">Attribute Table Manager</a><br>
  <a href="wxGUI.Nviz.html">3D Viewer</a><br>
  <a href="wxGUI.Modeler.html">Graphical Modeler</a><br>
  <a href="wxGUI.GCP_Manager.html">Manage Ground Control Points</a><br>
  <a href="wxGUI.PsMap.html">Cartographic Composer</a><br>
</em>

<p>
<em>
<a href="v.edit.html">v.edit</a>,
<a href="v.category.html">v.category</a>
</em>

<p>
See also <a href="http://grass.osgeo.org/wiki/WxGUI_Vector_Digitizer">wiki</a> page.

<h2>AUTHORS</h2>

<a href="http://geo.fsv.cvut.cz/gwiki/Landa">Martin
Landa</a>, <a href="http://www.fbk.eu">FBK-irst</a> (2007-2008),
Trento, Italy, and <a href="http://www.cvut.cz">Czech Technical
University in Prague</a>, Czech Republic<br>

<p>
<i>$Date$</i>