The GRASS tool r.digit provides the user with a way to draw lines, areas, and circles on a monitor screen, and to save these features in a raster map. Lines, areas, and circles are to be drawn using a pointing device (mouse). A mouse button menu indicates the consequences of pressing each mouse button. The user is requested to enter the category number associated with the line, area, or circle subsequently drawn by the user. Lines, areas, and circles are defined by the series of points marked by the user inside the map window. r.digit will close areas when the user has not. By drawing a series of such features, the user can repair maps, identify areas of interest, or simply draw graphics for advertisement. When drawing is completed, a raster map based on the user's instructions is generated. It is available for use as a mask, in analyses, and for display.

The bgcmd option is intended to be used with display (d.*) commands. If several display commands are to be used to render the background they should be separated with the semi-colon ';' character. When run from the command line, these display commands will generally need to be "quoted" as they will contain spaces (see examples).

Digitizing is done in a "polygon" method. Each area is circumscribed completely. Two or more overlapping areas and/or lines might define a single part of a map. Each part of the map, however, is assigned only the LAST area or line which covered it.


Start a monitor and display a raster to help setup and zoom to area of interest

d.mon x0

Digitizing an area based on a existing map; creating a new raster map

r.digit out=name_of_new_raster_map bgcmd="d.rast map=name_of_raster"
  1. Choose to define an area or line, exit, or quit. If you choose to finish (exit) a new map is then created. If you quit, the session exits with nothing created.
  2. If you choose to make an area or line you must identify the category number for that area or line.
  3. Using the mouse trace the line or circumscribe the area; or, finish (go to Step 1).


v.digit, d.graph, d.linegraph, g.region,, r.mapcalc,,


Michael Shapiro, U.S.Army Construction Engineering Research Laboratory

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