Elevation-Slope Plot

Option on Analyze menu calculates statistics for the current data set, and then displays several graphs. The program does an automatic assignment to about 100 elevation bins; the exact number depends on the elevation range and each bin having the same size.

Control graphs drawn.

Slope frequency: slope value in percent versus number of points. Because of the quantized nature of slope values because most DEMs record elevation only to the nearest meter, these plots may not be comparable for DEMs at different data spacing.  You can also get a slope histogram by Creating a  derivative grid
Slope vs elevation: elevation versus average slope, as in Moore and Mark (1993). This diagrams shows where generally steep and generally flat areas occur in terms of elevation. 

The computer also plots the standard deviation for slope in each elevation bin, showing the relative variability of slope at different elevations. The thin green and blue lines show one standard deviation above and below the average elevations.

This diagram shows slope in percent.

Slope vs elevation: same diagram as above, but with slope in degrees.
Cumulative slope: slope value in percent versus cumulative percent gentler on a normal probability axis; this avoids many of the problems with quantized slopes that are present in the slope frequency plot.
Aspect Distribution (Rose diagram):
Elevation distribution:
  • Slope method: 8 neighbors (even)
  • DS_30M
  • Max slope: 345.95% 73.9
  • Average slope: 27.29% 15.3
  • Standard deviation: 23.36 (%)
  • RMS 35.93 (%)
Text results.

 


Last revision 2/11/2010