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wxGUI Vector Digitizer


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

       Note that only vector maps stored or generated in the current mapset  can  be  opened  for

       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 toolbar .  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.  This "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 Map Display 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  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

             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

             Edit line/boundary
           Edit selected linear feature, add new segments or remove existing segments  of  linear

             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.

             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 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) 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 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

           ·   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 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

       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.


           ·   GRASS Vedit Library

           ·   Vector Database Management (Wiki page)


       wxGUI components

        v.edit, v.category,

       See also the WxGUI Vector Digitizer Wiki page including video tutorials.


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

       $Date: 2015-08-03 14:53:38 +0200 (Mon, 03 Aug 2015) $


       Available at: wxGUI Vector Digitizer source code (history)

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