UPPER COLCA ARCHAEOLOGICAL RESEARCH PROJECT
Arequipa, Peru

DEM COMPARISON

DEM data acquired from space- borne remote sensing platforms are becoming available for most of the planet surface. This study compares the vertical accuracy of this data with GPS derived data.

Ground control points collected using a Trimble Geoexplorer II GPS and then these data were differentially corrected using Pathfinder Office 2.90 with the AREQ IGS base station (100 km away) yielding a vertical accuracy estimated by the Trimble software to be ~3m (see table, col B). 

The ASTER DEM data was corrected using these exact GPS values by JPL, this is an "absolute" as opposed to "relative" (uncorrected) ASTER DEM.

Click to see table and graph showing divergence in elevation values between GPS, ASTER, and SRTM90.

In general the SRTM data has values significantly lower than either the GPS or the ASTER DEM.

We await improvements to the processing of SRTM as this coarse data is first generation release had a lot of speckling errors as well. 

N.T.

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