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Geomorphometry from SRTM: Comparison to NED

Peter L. Guth

Photogrammetric Engineering & Remote Sensing, Mar 2006, 72(3): p.269-277.


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Figure 3.  Map showing the distribution of Elevation-Relief ratio (ELEV_RELF) over the United States , computed with NED.  Fenneman’s physiographic provinces outlined to show the correspondence of this parameter to recognized boundaries.


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Figure 6.  Correlation coefficients of the best fit line for the 4 SRTM data sets compared to NED.  (A) shows 1” NED and all data in the United States, (B) shows 1” NED and only areas with average slope greater than 5%, (C) shows 2”NED and all data in the United States, and (D) shows 2” NED and areas with average slope greater than 5%.  Decimation/thinning of 1” NED created the 2” NED.  Note than restricting the analysis to slopes above 5%, or comparing SRTM to 2” NED, improves the correlations.  These graphs show all 33 parameters listed in Appendix A below; the version in the paper only shows the 12 parameters deemed most important. Note that some of these parameters on the bottom of each figure never show a correlation coefficient above 0.2. 


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Figure 7.  Slopes of the best fit line for the 4 SRTM data sets compared to NED.  (A) shows 1” NED and all data in the United States, (B) shows 1” NED and only areas with average slope greater than 5%, (C) shows 2”NED and all data in the United States, and (D) shows 2” NED and areas with average slope greater than 5%.  Decimation/thinning of 1” NED created the 2” NED. With the exception of the PLANC_STD parameter for the 2” NED, the slopes are everywhere less than 1, meaning that SRTM always computes smaller values of the statistics than NED.  These graphs show all 33 parameters listed in Appendix A below; the version in the paper only shows the 12 parameters deemed most important.


Appendix A.  33 Geomorphometric Parameters

The 12 parameters in bold are those discussed in the printed version of the paper. The others are included in Figures 6 and 7 here.

Additional references for Appendix A.