Dear list,
I’m trying to read in a greyscale georefrenced TIF file. I have successfully read in georeferenced color TIF files and sliced them into smaller sections, but I am having a great deal of trouble with this greyscale image.
First off I realized after playing with it that the greyscale required using d.rast while the color needed d.rgb… So far ok…
The color file was in lat/long so I read it into a lat/long location. The greyscale seems to be UTM, so I tried both UTM and XY locations. Both work for reading in and doing a d.rast and writing the file out as a PNG, but I can’t seem to slice the files up into smaller chunks.
When I first read in the file, I call :
r.in.gdal –o –e input=/Volumes/Recent/SB/p663east.tif output=temp
g.region –p gives me :
GRASS 6.0.0 (LocationText):~ > g.region -p
projection: 0 (x,y)
zone: 0
north: 3821818.5
south: 3806127.5
west: 251135.5
east: 276337.5
nsres: 1
ewres: 1
rows: 15691
cols: 25202
d.mon start=PNG
d.rast –o map=temp
d.mon stop=PNG
And I get a nice grainy map of my original tif file
Then I try
g.region n=3815204.19 s=3812771.11 w=235544.84 e=238598.83
GRASS 6.0.0 (LocationText):~ > g.region -p
projection: 0 (x,y)
zone: 0
north: 3815204.19
south: 3812771.11
west: 235544.84
east: 238598.83
nsres: 0.09999918
ewres: 0.09999967
rows: 24331
cols: 30540
d.mon start=PNG
d.rast –o map=temp
d.mon stop=PNG
And now I get a nice black image for a PNG file…
Same thing happens in the UTM location…
I’m stumped.
Thanks for your patience…
- sharyn