[GRASS-dev] CELL/FCELL/DCELL [was: Re:
r.mapcal rand() strangeness]
tutey at o2.pl
Sat Mar 1 17:18:15 EST 2008
Glynn Clements pisze:
> Maciej Sieczka wrote:
>> I was going to add this information, but I'm not sure if I understand
>> correctly that GRID3D is always floating point. Raster intro seems to
>> suggest so, but r3.mapcalc suggests the opposite, eg.: "Note: If you
>> calculate with integer numbers, the resulting map will be integer".
>> Please tell me.
> I suspect that's probably an artifact of verbatim copying from the
> r.mapcalc documentation.
> I'm fairly sure that G3D only supports FP.
Can you confirm if double precision only? I guess so by experiments with
r3.mapcalc - eg.:
$ r3.mapcalc 'map=float(1)'
$ r3.info map -t
> Looking at the r3.mapcalc code, the only way that you can get CELL
> values from a 3D grid is if you use the various # operators to perform
> colour lookups.
It still yields double for me:
$ r3.mapcalc 'map_g=g#map'
$ r3.info map_g -t
Can anybody please say what is the official name for GRASS 3d raster
data, which should be used in the raster intro? So far I have found the
$ cd /usr/local/grass-6.3.svn/docs/html$
$ grep -r -i "3d raster" . | wc -l
$ grep -r -i voxel . | wc -l
$grep -r -i g3d . | wc -l
$ grep -r -i GRID3D . | wc -l
$ grep -r -i "3d cell" . | wc -l
"3d cell" (which r3.info uses in it's output too BTW) seems kindoff
strange - 3d rasters are supposed to be only FP data type, whereas in 2D
raster GRASS lingo "CELL" designates the integer data type.
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