If you find this document usefull, please consider ordering a printed hardcopy!

7 Digitizing raster data

GRASS offers the possibility to digitize points, lines and areas based on raster via the module r.digit. Thereby, each feature can be assigned with a category value and a label:

r.digit
Please choose one of the following
   A define an area
   C define a circle
   L define a line
   Q quit (and create map)

In this way it is very simple to create masks - but not necessarily precise.