[Gdal-dev] Different UTM Zones...
tylermitchell at shaw.ca
Sat Aug 7 23:35:51 EDT 2004
On August 7, 2004 06:48 pm, StefanReisser at t-online.de wrote:
Hi Stefan - lots of questions! That's good :)
> I have a huge GeoTiff image and I want to extract that part, that
> perfectly matches a specific DEM file.
> It's easy, as long as both the image and the DEM use the same projection
> and geographic coordinate system.
> However, if the UTM zones are different, or the geographic coordinate
> system is different, how can I compute the raster coordinates
> of the DEM inside the GeoTiff image?
> How can I convert coordinates between different UTM zones and
> furthermore, how can I convert between Lat/Long and UTM coordinates?
A Proj4 utility called cs2cs (coordinate system 2 coordinate system) will
probably do the trick for you, unless you want to actually reproject your
Get the extent of the DEM and put the pair of coordinates (one x y pair per
line) into a text file. Then run cs2cs with a few options to have those
coordinates reprojected and printed to your screen.
Contents of utm.txt (easting, northing)
Project from one UTM zone to another:
> cs2cs +proj=utm +zone=10 +to +proj=utm +zone=11 utm.txt
4649861.81 414740.36 0.00 (0.00 is elevation which I left blank)
To project from UTM to lat/long:
> cs2cs +proj=utm +zone=10 +ellps=GRS80 +to +proj=latlong utm.txt
123d41'33.592"W 49d39'1.696"N 0.000
If your file has y then x (as opposed to x then y which is default) add the
option "-r" to the command.
So using cs2cs you should be able to get the projwin coordinates you need to
use gdal_translate to cut out a piece of an image you are interested in.
> gdal_translate -projwin <upper left x> <upper left y> <lower right x>< lower
right y> image1.tif clipped.tif
Will clip the area you want.
You could then, optionally reproject from one coordinate system to another
Let us know if you need more help using these utilities.
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