Importing ASCII DEM's to your GIS

ArcView/ArcINFO: The first six (GRASS) header lines (Newark East) will look like this:

     north: 4400273
     south: 4386353
     east: 446481
     west: 435621
     rows: 464
     cols: 362
Use any plain text editor (e.g. vi, Notepad, not MS-Word!) to convert these to ArcView/ArcINFO ASCII grid header format:
     xllcorner 435621
     yllcorner 4386353
     nrows 464
     ncols 362
     cellsize 30
     nodata_value 0
Here you specify just the X and Y lower-left corners (the West and South edges). Note that GRASS prior to version 5.0 doesn't distinguish between zero and missing data, but ArcINFO and ArcView do. If you are running ArcINFO under UNIX, you can download Jian Chen's grass2grid UNIX shell script which will do the header conversion automatically. Then in ArcINFO, use the ASCIIGRID module. In ArcView, with the Spatial Analyst extension loaded and an active View, use File--Import Data Source (ASCII Raster) to import the grid to ArcView.

GRASS: These are GRASS ASCII export files, and should re-import to GRASS directly with the r.in.ascii module.

IDRISI: Move or copy the DEM file into the IDRISI data environment directory. Then use File--Import--Software Specific Formats--GRASSIDR.

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