Topographic position#

Algorithm ID: hedgetools:topographicposition

This tool is based on GRASS GIS’s Geomorphons. For more details, you can consult the tool’s help page: r.geomorphon.

The algorithm assigns to each hedge the main topographic position it occupies. Geomorphon detects 10 categories: Flat, Peak, Ridge, Shoulder, Spur, Slope, Hollow, Footslope, Valley, Pit.

Note

It is recommended not to use a DTM with very high resolution, as it may create numerous small topographic variations, introducing noise in the results.

Note

Since hedges can traverse multiple topographic forms, it is recommended to split them first using the Split by Interval algorithm.

Parameters#

Label	Name	Type	Description
Input polygon layer	`INPUT`	[vector: polygon]	Polygon vector layer representing the hedges.
Input elevation raster (DTM)	`RASTER`	[raster]	Digital Terrain Model describing the ground elevation without obstacles.
Elevation band	`BAND`	[raster band] Default: 1	Elevation band of the DTM raster in case of multiband.
Search radius (meters)	`SEARCH`	[numeric: double] Default: 100.0	Maximum distance around each cell used by the geomorphon algorithm to define the surrounding topography.
Skip radius (meters)	`SKIP`	[numeric: double] Default: 50.0	Distance used by the topography algorithm to ignore small irregularities when constructing topographic forms.
Kernel size (pixels)	`KERNEL_SIZE`	[numeric: integer] Default: 7	Kernel size of the median filter applied after geomorphon analysis to smooth local variations. Must be odd. Larger kernels remove more noise.
Output topographic position layer	`OUTPUT`	[vector: polygon] Default: `[Create temporary layer]`	Output polygon vector layer.

Outputs#

Label	Name	Type	Description
Output topographic position layer	`OUTPUT`	[vector: polygon]	Polygon vector layer with a new field `topo_position` indicating the main topographic position of hedges.