[GRASSLIST:4008] setting NULL value in raster maps

[Thomas Dewez]

Dear list,

I could not seem to find this question answered in the documentation nor on
the archives. I would like to interpolated a DEM from a raster image, which
actually is a post-processed photogrammetric DEM exctracted with Orthomax
(for those of you who are curious). I imported it in Grass5pre3 running on
Cygwin as a raw binary file.

The image contains irregularly spaced pixels with either a correct Z value
or a NULL value (-9999). I am confused as to the procedure to follow. Do I
need to transform the raster to a site map? How do I tell the interpolation
s.surf.tps that it should only consider NOT(-9999) values?
I had a go using the r.null command but I would like to check that my input
map really contains NULL databefore proceeding. In clear how does one report
the content of an image indicating the presence of NULL (r.info keeps
telling me that min=-9999 even after r.null command).

Does this make any sense?
Thanks for your help

Thomas

_________________________________
Thomas Dewez

PhD research student
Dept Geography & E.S.
Brunel University
Uxbridge, UB8-3PH, Mddx
United Kingdom