NAME
r.prominence - calculates local prominence statistic.
(GRASS Raster Program)
DESCRIPTION
r.prominence computes a local (neighborhood) statistic that indicates
by how much a cell differs from the n cells surrounding it. In the
case of an elevation raster, this can be taken as the "prominence" of a location
in relation to its neighborhood. There is a growing body of literature on
the topic of topographic prominence in fields such as physical geography
and archaology. The statistic implemented in r.prominence is relatively
simple. The prominence "P" for a cell "i" is calculated as:
P=value(i)/avg
Where avg is the average value of the cells in the neighborhood of i.
USAGE DETAILS
Flags:
- -a
- Calculates "absolute" prominence. Negative output values will shifted into the positive range.
This leads to features with great negative difference from their surroundings (such as a deep canyon) to be marked as "positively prominent".
- -r
- Use a square instead of a circular neighborhood approximation. This will
result in faster computation but will give less accurate results.
- -q
- Disable progress display.
Parameters:
- input=name
- Name of a raster input map; usually an elevation map.
- radius=value
- Radius of neighborhood to use for computation,
expressed in number of cells. The larger, the more processing time will be needed.
This parameter reflects the scale-dependency of the statistic: Larger radii will
accentuate features that are prominent over a larger area, whereas smaller radii will
also accentuate those features that only stick out in their immediate neighborhood.
NOTES
Computation of the prominence statistic can be time-consuming, especially for
raster maps with many cells and for large neighborhoods.
The prominence statistic is fully subject to the "modifiable areal unit" (MAU) effect.
Towards the edges of the input raster, results will get unreliable. Therefore, make sure to allow
for sufficient buffer space (the size of radius=) in the input raster around all locations of interest.
You can use r.normalize to normalize prominence computations for different input maps and make them comparable.
SEE ALSO
Wikipedia article: Topographic prominence
Llobera, M. 2001. Building Past Landscape Perception With GIS: Understanding Topographic
Prominence. Journal of Archaeological Science 28:1005-1014.
AUTHOR
Benjamin Ducke, for Oxford Archaeology (http://oadigital.net)