wxGUI Vector Digitizer
The vector digitizer
is a wxGUI
component intended for interactive editing and digitizing vector maps
vector editing GRASS capabilities).
Note that only vector maps stored or generated in the current
mapset can be opened for editing.
The digitizer allows editing of 2D vector features (points, lines,
centroids, boundaries, and areas).
Vector features can be selected by mouse (bounding box or simply by
mouse click, see select threshold
in Settings→General→Select threshold), or by query
(eg. by line length, see Settings→Query Tool).
The vector digitizer can be launched from Map Display toolbar by selecting
"Digitize" from Tools
combobox. Vector map is
selectable for editing from Digitizer toolbar ("Select vector
map" combobox, note that only vector maps from the current layer
tree in Layer Manager are listed).
The vector digitizer can alternatively be activated from the contextual
menu in the Layer Manager by selecting "Start editing" on selected vector
map in the layer tree, or directly from the Layer Manager
The vector digitizer also can also be launched from the command line as a
stand-alone application g.gui.vdigit
A new vector map can be easily created from the 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 the digitizer toolbar also allows easily switching between
vector maps to be edited.
An existing vector map selected in the digitizer toolbar in the
"Select vector map" combobox. This map is then opened for editing
and added to the current layer tree in the Layer Manager
"Select vector map" combobox in the digitizer toolbar also allows
to easily switch between vector maps to be edited.
In order to digitize from a raster map, simply load the map into the
using the Layer Manager
. Then start digitizing,
see below for details.
The vector digitizer allows you to select a "background" vector map.
Loading it within the digitizer is different from simply loading it via
since direct interaction with single vector features
then becomes possible.
Vector features may be copied from the background map by "Copy features from
(background) vector map" tool from the "Additional tools" of the
Newly digitized vector features are snapped in the given threshold to the features
from the background map.
Digitize new point
- Add new point to vector map and optionally define its
Digitize new line
- Add new line to vector map and optionally define its
Digitize new boundary
- Add new boundary to vector map and optionally define its
Digitize new centroid
- Add new centroid to vector map and optionally define its
Digitize new area
- Add new area (closed boundary and one centroid inside) to vector
map and optionally define its attributes.
- Move selected vertex of linear feature. Thus shape of linear
feature is changed.
- Add new vertex to selected linear feature (shape not
- Remove selected vertex from linear feature. Thus shape of selected
feature can be changed.
- Edit selected linear feature, add new segments or remove
existing segments of linear feature.
- Move selected vector features. Selection can be done by mouse or
- Delete selected vector features (point, line, centroid, or
boundary). Selection can be done by mouse or by query.
- Delete selected vector areas. Selection can be done by mouse
or by query.
- Display categories of selected vector feature. Category settings
can be modified, new layer/category pairs added or already defined pairs
- 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
- Break selected lines/boundaries at intersection
given vector line or boundary into two lines on given position
(based on v.clean,
- Connect two selected lines/boundaries
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) vector 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
- Feature type conversion
Change feature type of selected
geometry features. Points are converted to centroids,
centroids to points, lines to boundaries and boundaries to
- 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
- Snap selected lines/boundaries (only to nodes)
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
- Split line/boundary
Split selected line or boundary on
- 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 previous operations.
- Redo previous operations.
- Digitizer settings.
Quit digitizing tool
- Changes in vector map can be optionally discarded when
digitizing session is quited.
- Mouse button functions:
- Left - select or deselect features
- Control+Left - cancel action or undo vertex when digitizing lines
- Right - confirm action
Dead (deleted) features are only marked as 'dead' in the geometry file
but remain there and occupy space. Any vector module
used afterwards on this vector map which really reads and writes
vector geometry (so not g.copy)
will write 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, the changes are
automatically saved. Broken topology can be repaired by running
GRASS GIS uses a topological vector format, meaning that a common boundary of
two polygons is only stored once. When digitizing polygons it is thus important
to be able to only draw each boundary once. When drawing a polygon adjacent to an
existing polygon, one has to first split the existing boundary at the points where
the new boundary will be attached. Snapping should be set to ensure that the new
boundaries are automatically attached to the chosen points.
See also the WxGUI Vector Digitizer Wiki page
Martin Landa, FBK-irst (2007-2008), Trento, Italy, and Czech Technical
University in Prague, Czech Republic
Available at: wxGUI Vector Digitizer source code (history)
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GRASS Development Team,
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