[GRASSLIST:7170] crop of raster - once again

Axel Orth axel_orth at gmx.de
Wed Jun 15 09:57:33 EDT 2005

I had some success with cropping my raster maps with borders of 
municipalities (available as vector - converted to raster) and thought I 
figured out how it works.

But now I try do do the same with some other data and strange things happen:

import raster map "MAP" - import vector "V" - do raster conversation 
with vector and get the raster map "V_rast"
set the region: g.region rast=V_rast zoom=V_rast
create the mask: g.copy V_rast,MASK
create new map based on the existing map while only the area of the mask 
is taken into consideration: r.mapcalc MAP_crop=MAP

Problem: the resulting map MAP_crop is just a colored rectangle - the 
size of the rectangle is equal to the bounding box of V_rast

By chance I made some errors and somehow got the result i wanted:
instead of the r.mapcalc command shown above I did:

MAP_crop=MAP end -> syntax error
r.mapcalc MAP_crop=MAP

MAP looks now exactly the way I wanted. When I leave GRASS, start again 
then MAP looks like I had when imported it.

I have no clue what's this is all about and hope someone has a idea.


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