do resolution changes effectively average data ?

Malcolm Williamson malcolm at
Wed Jan 18 12:42:42 EST 1995

> Hello,
> 	In grass, if you have a 10 metre grid resolution raster data layer and
> you go from 10 metre resolotion to 100 metre resolution using g.region, and then
> perform an operation on that raster data layer; -  does the opertion occur on an
> averaged value from all original 10 metre grid cells in order to produce the new
> 100 metre grid raster - or does the operation occur only on the top left 10
> metre grid cell value within the new 100 metre grid? Or does something else
> happen?
> 	Cheers, Al.
GRASS resamples based on the value of the center cell. If there is no center
cell (as in your example), it would take the value of the upper-left cell
out of the center four, *not* the upper-left cell of the 10 x 10 block.

Not a great explanation; I hope it makes sense!
Malcolm D. Williamson - GIS Specialist           E-mail: malcolm at
Center for Advanced Spatial Technologies      Telephone: (501) 575-6159
Ozark Rm. 12                                        Fax: (501) 575-5218 
University of Arkansas              
Fayetteville, AR 72701

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