[GRASSLIST:426] RE: Maximum number of colors in rasters

Hamish,

Thanks for the info.

Wild guess as to why you are asking this:
your output looks like it has like 256 contoured bands when you think it
should be (perceivably) continuous. try this:

r.mapcalc 'elev_int=int(elev)'
r.colors elev_int rast=elev # maybe redundant
d.rast elev_int

[mult the DCELL map by 10000 before int() if decimal places are
significant]

For some reason I don't understand, floating point maps don't do smooth
color transitions. On the other hand I have used this "feature" on
occasion to enhance a raster map hardcopy (sometimes you want the subtle
contour lines).

Yes, this was the issue that a colleague was having. I was at a loss to
explain why it seemed there were explicit breaks occurring in the bathymetry
data.

I tried to document this ~1-2 years ago I think. If interested search
through the mailing list archive or the bug tracker for the post.
commonly seen: scale a lat/lon SRTM map to 1:1:1 XYZ for NVIZ by
dividing elev map by 60*1852. set some colors with r.colors and then d.rast

both

original CELL and new DCELL maps.

Great, thanks, I'll pore through the archives for this thread; this stuff is
good to know.

Cheers,

~ Eric.