SAGA-GIS Tool Library Documentation (v7.8.2)

Tool Multi-Scale Topographic Position Index (TPI)

Topographic Position Index (TPI) calculation as proposed by Guisan et al. (1999).

This implementation calculates the TPI for different scales and integrates these into one single grid. The hierarchical integration is achieved by starting with the standardized TPI values of the largest scale, then adding standardized values from smaller scales where the (absolute) values from the smaller scale exceed those from the larger scale. This integration scheme has been proposed by N. Zimmermann.


References


Parameters

 NameTypeIdentifierDescriptionConstraints
InputElevationGrid, inputDEM--
OutputTopographic Position IndexGrid, outputTPI--
OptionsGrid SystemGrid systemPARAMETERS_GRID_SYSTEM--
Minimum ScaleIntegerSCALE_MINkernel radius in cellsMinimum: 1
Default: 1
Maximum ScaleIntegerSCALE_MAXkernel radius in cellsMinimum: 1
Default: 8
Number of ScalesIntegerSCALE_NUM-Minimum: 2
Default: 3
UpdateBoolean, GUIUPDATEupdate view for each integration stepDefault: 0

Command-line

Usage: saga_cmd ta_morphometry 28 [-DEM <str>] [-TPI <str>] [-SCALE_MIN <num>] [-SCALE_MAX <num>] [-SCALE_NUM <num>]
  -DEM:<str>      	Elevation
	Grid, input
  -TPI:<str>      	Topographic Position Index
	Grid, output
  -SCALE_MIN:<num>	Minimum Scale
	Integer
	Minimum: 1
	Default: 1
  -SCALE_MAX:<num>	Maximum Scale
	Integer
	Minimum: 1
	Default: 8
  -SCALE_NUM:<num>	Number of Scales
	Integer
	Minimum: 2
	Default: 3