Notice to YSPilots/YSFLIGHT

Notice to YSPilots/YSFLIGHT
Legacy Pack available under the YSFLIGHT category.
Any individual requests for a model must be made to my email address, see bottom of the page..

Sunday, 12 March 2017

QGIS TPI Based Landform Classification Style

In SAGA GIS (and by extension - QGIS) there is a tool called Topographic Position Index.
It is a tool that assigns an index value based upon the land form feature - ridges and peaks are assigned positive values, and valleys are assigned negative values.

In addition to this tool - there is a TPI based landform classification - which takes that Position index, and classifies the landscape into different land forms, such as:

  • Canyons, deeply incised streams,
  • Mid-slope drainage, shallow valleys
  • Upland drainage, headwaters
  • U-shaped valleys
  • Plains
  • Open slopes
  • upper slopes/messas
  • local ridges/hills in valleys
  • midslope ridges, small hills in plains
  • Mountain tops and high ridges

Basically, I've created a QGIS style based upon the map used in the poster by A. Weiss.
3D plot over OS Terrain 50
© Crown Copyright and Database Right (2017). Ordnance Survey

Map view of TPI Landform Classification based on OS Terrain 50

The TPI Based Landform Classification is useful for determining the landform characteristics for a given area - and by classifying them into set categories, one can compare landforms in different areas. 

To use the tool you need a DEM, and QGIS. 
The tool is located in the Processing Toolbox under SAGA>Terrain Analysis - Morphology > TPI based landform classification