Multi-Scale Topographic Position Index (TPI)
- Author: O.Conrad (c) 2016
- Menu: Terrain Analysis | Morphometry
Description
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
- toposcale.aml script by N.Zimmermann
- Guisan, A., Weiss, S.B., Weiss, A.D. (1999): GLM versus CCA spatial modeling of plant species distribution. Plant Ecology 143: 107-122.
- Weiss, A.D. (2000): Topographic Position and Landforms Analysis. Poster http://www.jennessent.com/downloads/tpi-poster-tnc_18x22.pdf.
- Wilson, J.P. & Gallant, J.C. (2000): Primary Topographic Attributes. In: Wilson, J.P. & Gallant, J.C. [Eds.]: Terrain Analysis: Principles and Applications, John Wiley & Sons, p.51-85.
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | Elevation | grid, input | DEM | - | - |
| Output | Topographic Position Index | grid, output | TPI | - | - |
| Options | Grid System | grid system | PARAMETERS_GRID_SYSTEM | - | - |
| Minimum Scale | integer number | SCALE_MIN | kernel radius in cells | Minimum: 1
Default: 1 |
| Maximum Scale | integer number | SCALE_MAX | kernel radius in cells | Minimum: 1
Default: 8 |
| Number of Scales | integer number | SCALE_NUM | - | Minimum: 2
Default: 3 |
| Update | boolean, GUI | UPDATE | update view for each integration step | Default: 0 |
Command Line
Usage: saga_cmd ta_morphometry 28 [-DEM ] [-TPI ] [-SCALE_MIN ] [-SCALE_MAX ] [-SCALE_NUM ]
-DEM: Elevation
grid, input
-TPI: Topographic Position Index
grid, output
-SCALE_MIN: Minimum Scale
integer number
Minimum: 1
Default: 1
-SCALE_MAX: Maximum Scale
integer number
Minimum: 1
Default: 8
-SCALE_NUM: Number of Scales
integer number
Minimum: 2
Default: 3