topic Re: Zonal Statistics Table_Data reduced in ArcGIS Spatial Analyst Questions

Zonal Statistics Table_Data reduced

BenMayala — Tue, 11 Oct 2011 15:20:04 GMT

Hi

I???m using Zonal Statistics as a Table in ArcGIS 10 to get Min, Max and Mean values.

My Input or feature zone data is a country shapefile with a certain number of provinces
The input value raster is an image with the same extent (country shape)

What I need is to have values in all provinces, but I???m getting an output table with less number of provinces (for example the number decreased to 90, from 140)
I can???t figure out what could be the problem, why it doesn???t consider the other provinces.

Thanks

Ben

Re: Zonal Statistics Table_Data reduced

LornaMurison — Tue, 11 Oct 2011 18:32:41 GMT

How big are your provinces, and what is the resolution of the grid?
Sometimes if there are only a few grid cells underlying the polygon, then it will be ignored.

If that is the problem, here is one potential work-around.
http://resources.arcgis.com/gallery/file/geoprocessing/details?entryID=EDC215BC-1422-2418-3467-416ECAC40414

Re: Zonal Statistics Table_Data reduced

JeffreySwain — Wed, 12 Oct 2011 10:30:23 GMT

I would consider the cell size of the raster and the rasterized version of the polygons. For the zone to be recognized, the centroid of the raster needs to fall within the area identified as a zone. If you are lacking the information, I would consider resampling the input raster to a finer spatial resolution or smaller cell size and it may help with the correct number of zones being returned.