GRASS GIS Manual: wxGUI.Vector_Digitizer

## NAME

wxGUI.Vector_Digitizer

## DESCRIPTION

The vector digitizer is a wxGUI component intended for interactive editing vector maps (see v.edit for non-interactive vector editing GRASS capabilities).

The digitizer supports editing of 2D vector features (points, lines, centroids, boundaries, and area). 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->General->Select threshold' value).

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.

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.

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.

### DIGITIZER TOOLBAR

Digitize new point
  Add new point to vector map and optionally define its attributes.
Digitize new line
  Add new line to vector map and optionally define its attributes.
Digitize new boundary
  Add new boundary to vector map and optionally define its attributes.
Digitize new centroid
  Add new centroid to vector map and optionally define its attributes.
Digitize new area
  Add new area (closed boundary and one centroid inside) to vector map and optionally define its attributes.
Move vertex
  Move selected vertex of linear feature. Thus shape of linear feature is changed.
Add vertex
  Add new vertex to selected linear feature (shape not changed).
Remove vertex
  Remove selected vertex from linear feature. Thus shape of selected feature can be changed.
Edit line/boundary
  Edit selected linear feature, add new segments or remove existing segments of linear feature.
Move feature(s)
  Move selected vector features. Selection can be done by mouse or by query.
Delete feature(s)
  Delete selected vector features (point, line, centroid, or boundary). Selection can be done by mouse or by query.
Display/update categories
  Display categories of selected vector feature. Category settings can be modified, new layer/category pairs added or already defined pairs removed.
Display/update attributes
  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)".
Additional tools
  - Break selected lines/boundaries at intersection
    Split given vector line or boundary into two lines on given position (based on v.clean, `tool=break`).
  - Connect two selected lines/boundaries
    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.
  - Copy categories
    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.
  - Copy features from (background) map
    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.
  - Copy attributes
    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.
  - Feature type conversion
    Change feature type of selected geometry features. Points are converted to centroids, centroids to points, lines to boundaries and boundaries to lines.
  - Flip selected lines/boundaries
    Flip direction of selected linear features (lines or boundaries).
  - Merge selected lines/boundaries
    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 v.build.polylines.
  - Snap selected lines/boundaries (only to nodes)
    Snap vector features in given threshold. See also module v.clean. Note that this tool supports only snapping to nodes. Snapping to vector features from background vector map is not currently supported.
  - Split line/boundary
    Split selected line or boundary on given position.
  - Query tool
    Select vector features by defining a threshold for min/max length value (linear features or dangles).
  - Z-bulk labeling of 3D lines
    Assign z coordinate values to 3D vector lines in bounding box. This is useful for labeling contour lines.
Undo
  Undo previous operations.
Settings
  Dialog for vector digitizer settings.
Quit digitizing tool
  Changes in vector map can be optionally discarded when digitizing session is quited.

## NOTES

Mouse button Functions:
Left - select/deselect features
Control+Left - cancel action/undo vertex
Right - confirm action

Dead (deleted) 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 g.copy) will writes only features which are 'alive'.

Added or modified vector features are snapped to existing vector features (Settings→General→Snapping). To disable snapping set the snapping threshold to '0'.

If the digitizer crashes for some reason you can repair the vector map which was left open with the v.build module.

## REFERENCE

- GRASS Vedit Library

## SEE ALSO

wxGUI
wxGUI components

v.edit, v.category, v.build

See also the wiki page including video tutorials.

## AUTHOR

Martin Landa, FBK-irst (2007-2008), Trento, Italy, and Czech Technical University in Prague, Czech Republic

$Date: 2013-02-15 14:04:18 -0800 (Fri, 15 Feb 2013) $

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