Hi,
Not sure if this is very critical, but I have noticed a problem with
r.shaded.relief. If the region is set to 10m and then a shaded rel. map is
produced from a 30m input data, a corrupt map is produced.
example with spearfish data:
# set region, and force 10m resolution
g.region rast=elevation.10m -p
# compute shaded rel. map from 30m res data:
# see image [1]
r.shaded.relief map=elevation.dem shade=shade
# compute shaded rel. map from 10m res data:
# see image [2]
r.shaded.relief map=elevation.10m shade=shade --o
1. http://169.237.35.250/~dylan/temp/bad_shade.png
2. http://169.237.35.250/~dylan/temp/good_shade.png
This was done with today's SVN.
--
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341
Not sure if this is very critical, but I have noticed a problem with
r.shaded.relief. If the region is set to 10m and then a shaded rel. map is
produced from a 30m input data, a corrupt map is produced.
example with spearfish data:
# set region, and force 10m resolution
g.region rast=elevation.10m -p
I assume you meant g.region rast=elevation.10m res=10 -ap ?
# compute shaded rel. map from 30m res data:
# see image [1]
r.shaded.relief map=elevation.dem shade=shade
I can't reproduce this. I can produce a Moire-patterned shaded-relief map,
since I didn't resample the 30m data to 10m:
ftp://gsca.nrcan.gc.ca/outgoing/Patton
The command-line I used:
g.region rast=elevation.dem res=10 -ap
projection: 1 (UTM)
zone: 13
datum: nad27
ellipsoid: clark66
north: 4928000
south: 4914020
west: 590010
east: 609000
nsres: 10
ewres: 10
rows: 1398
cols: 1899
cells: 2654802
r.shaded.relief map=elevation.dem shadedmap=elevation.dem.shade.10m
Try r.resample first?
~ Eric.
Patton, Eric wrote:
>Not sure if this is very critical, but I have noticed a problem with
>r.shaded.relief. If the region is set to 10m and then a shaded rel. map is
>produced from a 30m input data, a corrupt map is produced.
>
>example with spearfish data:
>
># set region, and force 10m resolution
>g.region rast=elevation.10m -p
I assume you meant g.region rast=elevation.10m res=10 -ap ?
># compute shaded rel. map from 30m res data:
># see image [1]
>r.shaded.relief map=elevation.dem shade=shade
I can't reproduce this. I can produce a Moire-patterned shaded-relief map,
since I didn't resample the 30m data to 10m:
Try r.resample first?
r.resample won't help. That uses libgis' built-in nearest-neighbour
resampling, so you will get exactly the same result as with using the
lower resolution map.
Using r.resamp.interp with method=bilinear or method=bicubic should
eliminate the problems with generating slope and aspect maps.
--
Glynn Clements <glynn@gclements.plus.com>
