Implement Topographic Position Index as a tool or toolset in Spatial Analyst tools.

03-31-2010 10:09 AM
Status: Open
Labels (1)
Esri Regular Contributor

I'd like and easy way to classify the landscape into both slope position (i.e. ridge top, valley bottom, mid-slope, etc.) and landform category (i.e. steep narrow canyons, gentle valleys, plains, open slopes, mesas, etc.).  There is an ArcView 3 script that helps me do this, but I'd prefer to stay in ArcGIS.  The script is here:

This extension calculates Topographic Position Index (TPI) grids from elevation grids, and provides a simple and repeatable method to classify the landscape into slope position and landform category using the TPI values. This extension also provides additional functions to standardize and classify grids, and to generate grid and neighborhood statistics.

There is an ArcGIS version of TPI...
We also support a variant of the TPI in the Benthic Terrain Modler (BTM), which can be used to classify terrestrial systems along with benthic ones:
Esri could add this as a function to a mosaic dataset or raster.   I found a site with 12 different types of ways to do ruggedness.   I have tested TPI and it's easily put in as a function you can build. 


I saw this download has other functions in it, TPI (Topographic Position Index - algorithm increasingly used to measure topographic slope positions and to automate landform classifications), TWI (Topographic Wetness Index - also known as the Compound Topographic Index - CTI ), Elevation Void Fill, and two types of TRI. Be sure to use the 32 Bit Float as output for the TPI, otherwise the default is just 0 and 1 image. TWI: