Luis Miguel Royo Perez wrote: > Hi everyone,
Hi Luis-Miguel! > maybe the question is not difficult, but i couldn't find the way to make > null data transparent, i've been reading the documentation, but still i > can't found the answer, if anyone could help me i'll apreciate a lot. > > Just indicate the name of algorythm that makes this and i'll study the > documentation. NULL cells (or call them No Data if you want) are by default "transparent" in GRASS GIS -- since they are empty cells, it is not possible to assign any value, hence it is not possible to assign a "color". Note, all raster operations on a NULL cell, will result always, unless instructed by the user otherwise, in a NULL cell. Check the following page -- search of course for the NULL string, as well as the MASK string which is a powerful concept in GRASS GIS): <http://grass.osgeo.org/grass64/manuals/rasterintro.html> If it is about drawing another map on top of another, then the default behaviour in GRASS 64 is to "erase" the underlying map, no matter if the drawn values are NULL or valid values, unless the user instructs the "-o" flag. See also: <http://grass.osgeo.org/grass64/manuals/d.rast.html>. In GRASS 70, the default drawing behaviour is inverted, i.e. the underlying map's cells are still visible wherever the map that is drawn on top holds NULL cells. The "-n" flag will make the NULL cells opaque. See also: <http://grass.osgeo.org/grass70/manuals/d.rast.html> Can you provide an example which or what is (still) confusing? Best, Nikos
signature.asc
Description: This is a digitally signed message part.
_______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
