xenial (1) wxGUI.vdigit.1grass.gz

wxGUI Vector Digitizer

DESCRIPTION

       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 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).

   STARTING THE DIGITIZER
       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.

   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 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.

   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 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.

             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 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.

             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     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 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

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

AUTHOR

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

       $Date: 2015-08-03 14:54:05 +0200 (Mon, 03 Aug 2015) $

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       © 2003-2016 GRASS Development Team, GRASS GIS 7.0.3 Reference Manual