Percent elevation range (PER) is a measure of local topographic position (LTP). It expresses the vertical position for a digital elevation model (DEM) grid cell (z0) as the percentage of the elevation range within the neighbourhood filter window, such that:

> PER = z0 / (zmax - zmin) x 100

where z0 is the elevation of the window's center grid cell, zmax is the maximum neighbouring elevation, and zmin is the minimum neighbouring elevation.

Neighbourhood size, or filter size, is specified in the x and y dimensions using the `filterx` and `filtery`flags. These dimensions should be odd, positive integer values (e.g. 3, 5, 7, 9, etc.).

Compared with `ElevPercentile` and `DevFromMeanElev`, PER is a less robust measure of LTP that is susceptible to outliers in neighbouring elevations (e.g. the presence of off-terrain objects in the DEM).

## References

Newman, D. R., Lindsay, J. B., and Cockburn, J. M. H. (2018). Evaluating metrics of local topographic position for multiscale geomorphometric analysis. Geomorphology, 312, 40-50.

## See Also

`ElevPercentile`, `DevFromMeanElev`, `DiffFromMeanElev`, relative_topographic_position

## Function Signature

`def percent_elev_range(self, dem: Raster, filter_size_x: int = 11, filter_size_y: int = 11) -> Raster: ...`

## Project Links

WbW Homepage User Manual Support WbW