Raster aggregate values - Revision history

⚠️DylanBeaudette: added some details regarding r.resamp.stats

2010-08-26T15:49:18Z

added some details regarding r.resamp.stats

← Older revision		Revision as of 15:49, 26 August 2010
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	* Run {{cmd\|v.rast.stats}} to calculate stats for each grid box, and upload to that area's attribute table.		* Run {{cmd\|v.rast.stats}} to calculate stats for each grid box, and upload to that area's attribute table.

			'''A:''' Another approach using {{cmd\|r.resamp.stats}}:
			* Generate a region that defines the required grid topology: extent, cell size, origin
			* Zoom to that region, and set the resolution accordingly
			* Aggregate slope values within each of the cells defined by this new region using {{cmd\|r.resamp.stats}}
			* The resulting raster will contain aggregate values of the input raster, using the new grid topology
			* Optionally vectorize with {{cmd\|r.to.vect}}


	~~''Perhaps a similar thing could be done using {{cmd\|r.resamp.stats}}?''~~

	[[category: FAQ]]		[[category: FAQ]]

⚠️HamishBowman: or r.resamp.stats

2010-08-26T09:46:29Z

or r.resamp.stats

← Older revision		Revision as of 09:46, 26 August 2010
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	* Draw a 1 km x 1 km grid ({{cmd\|d.grid}}), and overlay the {{cmd\|v.mkgrid}} vector map (area fill = none, or only display boundary features, colored red or so) just to verify where it will be and what it will look like.		* Draw a 1 km x 1 km grid ({{cmd\|d.grid}}), and overlay the {{cmd\|v.mkgrid}} vector map (area fill = none, or only display boundary features, colored red or so) just to verify where it will be and what it will look like.
	* Run {{cmd\|v.rast.stats}} to calculate stats for each grid box, and upload to that area's attribute table.		* Run {{cmd\|v.rast.stats}} to calculate stats for each grid box, and upload to that area's attribute table.



			''Perhaps a similar thing could be done using {{cmd\|r.resamp.stats}}?''

	[[category: FAQ]]		[[category: FAQ]]

Neteler: new, based on Hamish's notes

2010-08-26T08:48:35Z

new, based on Hamish's notes

New page

'''Q:''' How can I calculate the average map values by spatial unit (grid)? For example, I would like to calculate the average slope by square kilometer for a given area.

'''A:''' Procedure outline:

* Make a slope map from the DEM with {{cmd|r.slope.aspect}} at the same resolution and bounds as the DEM. (run 'g.region rast=dem' first)
* Make the grid with {{cmd|v.mkgrid}}, with box=1000,1000 (assuming the location is meters-based)
* Draw a 1 km x 1 km grid ({{cmd|d.grid}}), and overlay the {{cmd|v.mkgrid}} vector map (area fill = none, or only display boundary features, colored red or so) just to verify where it will be and what it will look like.
* Run {{cmd|v.rast.stats}} to calculate stats for each grid box, and upload to that area's attribute table.

[[category: FAQ]]