[GRASS-user] landsat and srtm blend

[alrc]

On Tue, 23 Oct 2007 16:29:10 -0700 (PDT), Hamish <hamish_nospam at yahoo.com>
wrote:
> alrc wrote:
> 
>> I try to make simple (in theory) shaded relief based on SRTM data and
> blend
>> it with Landsat7 RGB composite.
>> I have converted SRTM WRS2 (p187r025) tile from LatLong to UTM z34 to
> match
>> my Landsat data. The thing is that the landsat image is somewhat
>> rotated/skewed, which I guess is specific to ETM imagery rather than to
> UTM
>> projection. When I try to combine rasters using r.blend I get an
> misaligned
>> image.
> 
> No idea, other than check that you reprojected the landsat imagery
> correctly.
> How did you do the reprojection or import?
I reprojected only the SRTM tile using:
 gdalwarp -t_srs '+init=EPSG:32634' SRTM_ff03_p187r025.tif srtm_out.tif
where EPSG code 32634 matches the projection in landsat data.
Landsat image was acquired from GLCF site and it wasn't reprojected.

> You are sure that the SRTM is ok?
> Maybe try r.in.wms or r.in.onearth* to load in the landsat data?
I used r.in.gdal for landsat GeoTIFF import and the same for SRTM tif file,
but I can surely try r.in.onearth.

Right now I'm working on r.null and mapcalc but it seem like an overkill.

Regards,

alrc