Hi Xiaodong, On Sun, Dec 11, 2011 at 2:22 PM, Xiaodong Zhang <[email protected]> wrote: > I'm wondering if someone has done something like this and would like to > share the experience. Say, I have an image, e.g. NDVI, and a shapefile > define one or more areas (polygons) with the image. How to calculate the > statistics for each area, for example, the mean value of NDVI within each > polygon.
You'll see this operation referred to as "zonal statistics". GDAL has no utilities to do this directly but there are several open source implementations that do: - QGIS has a "Zonal Statistics" plugin - GRASS has this capability in the r.statistics module - R has a zonal() function - starspan is a GDAL-based application specifically for zonal stats. Any of the above might suite your needs depending on your desired workflow and programming environment. Good luck, -- ·´¯`·.¸. , . .·´¯`·.. ><((((º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º> "The best way to predict the future is to invent it." -- Alan Kay Matthew T. Perry http://www.perrygeo.net http://viedevelo.wordpress.com _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
