g.gui.vdigit(1grass) GRASS GIS User's Manual g.gui.vdigit(1grass)
NAME
g.gui.vdigit - Interactive editing and digitization of vector maps.
KEYWORDS
general, GUI, vector, editing, digitizer
SYNOPSIS
g.gui.vdigit
g.gui.vdigit --help
g.gui.vdigit [-c] map=name [--help] [--verbose] [--quiet] [--ui]
Flags:
-c
Create new vector map if doesn’t exist
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog
Parameters:
map=name [required]
Name of vector map to edit
Or data source for direct OGR access
DESCRIPTION
The vector digitizer is a wxGUI component intended for interactive
editing and digitizing vector maps (see v.edit for non-interactive vec-
tor 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, cen-
troids, boundaries, and areas).
Vector features can be selected by mouse (bounding box or simply by
mouse click, see select threshold in Settings→General→Select thresh-
old), or by query (eg. by line length, see Settings→Query Tool).
STARTING THE DIGITIZER
The vector digitizer can be launched from Map Display toolbar by se-
lecting "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 Man-
ager toolbar . The vector digitizer also can also be launched from the
command line as a stand-alone application g.gui.vdigit.
CREATING A NEW VECTOR MAP
A new vector map can be easily created from the digitizer toolbar by
selecting "New vector map" in "Select vector map" combobox. A new vec-
tor 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.
EDITING AN EXISTING VECTOR MAP
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. This "Select vector map"
combobox in the digitizer toolbar also allows to easily switch between
vector maps to be edited.
USING A RASTER BACKGROUND MAP
In order to digitize from a raster map, simply load the map into the
Map Display using the Layer Manager. Then start digitizing, see below
for details.
USING A VECTOR BACKGROUND MAP
The vector digitizer allows you to select a "background" vector map.
Loading it within the digitizer is different from simply loading it via
Layer Manager 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
digitizer toolbar. Newly digitized vector features are snapped in the
given threshold to the features from the background map.
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 at-
tributes.
Digitize new centroid
Add new centroid to vector map and optionally define its at-
tributes.
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 fea-
ture 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 bound-
ary). Selection can be done by mouse or by query.
Delete areas(s)
Delete selected vector areas. 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 cate-
gory settings). Attributes can be also modified. Same functional-
ity 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 po-
sition (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 nec-
essary 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 vec-
tor 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 back-
ground vector map has been selected from the Layer Manager,
copy features from background vector map, not from the cur-
rently 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 bound-
aries and boundaries to lines.
• Flip selected lines/boundaries
Flip direction of selected linear features (lines or bound-
aries).
• 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 sec-
ond line from two selected lines is in opposite direction to
the first, it will be flipped. See also module v.build.poly-
lines.
• 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.
Redo
Redo previous operations.
Settings
Digitizer settings.
Quit digitizing tool
Changes in vector map can be optionally discarded when digitizing
session is quited.
NOTES
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 fea-
tures (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 v.build.
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.
REFERENCES
• GRASS Vedit Library
• Vector Database Management (Wiki page)
SEE ALSO
wxGUI
wxGUI components
v.edit, v.category, v.build, wxGUI.rdigit
See also the WxGUI Vector Digitizer Wiki page including video tutori-
als.
AUTHOR
Martin Landa, FBK-irst (2007-2008), Trento, Italy, and Czech Technical
University in Prague, Czech Republic
SOURCE CODE
Available at: wxGUI Vector Digitizer source code (history)
Accessed: unknown
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GRASS 7.8.7 g.gui.vdigit(1grass)
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