TOPIC:

This Tech Tip discusses an error that can be encountered when trying to import a DEM in GeoTIFF format that uses the UTM coordinate system.

DISCUSSION:

In RiverTools 2.4 and 3.0, attempts to import certain GeoTIFF DEMs that use UTM coordinates (via File > Import DEM > GeoTIFF) will result in the following error dialog:

The error message refers to a GeoTIFF tag called ProjLinearUnitsGeoKey. This error message is the result of a bug that will be addressed in Service Pack 2 for RiverTools 3.0. GeoTIFF DEMs created by ENVI are among those than can trigger this message. The bug results from the fact that there are several different ways that the same georeferencing information can be encoded in GeoTIFF tags and different programs use different methods.

Note that ASTER (Advanced Spaceborne Thermal Emission and Reflectance Radiometer) DEMs, created from stereo images acquired by NASA's Terra satellite, are released in both GeoTIFF and HDF file formats. ASTER DEMs in GeoTIFF format can easily be imported into RiverTools 3.0.

If you have any additional questions or comments, please contact Rivix Technical Support for assistance.

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