I am using ArcGIS for a geology mapping project. I've mapped 500+ features as polygons using a basemap of a planet's surface. I want to get information regarding the "darkness," that is, the greyscale values (0-255) of the pixels contained within the polygons. Ideally I want the descriptive statistics of all the pixels (mean, mode, variance, etc.) contained within the bounds of the polygon.

Does such a tool exist in ArcToolbox, or has anyone ever heard of a plug-in for such a thing?

  • The Zonal Statistics tool will do some of what you want, it requires a Spatial Analyst license though. – Dan C Feb 14 '17 at 17:42
  • How can I get a Spatial Analyst license? Is it something I can purchase? – Jessica Feb 14 '17 at 17:45
  • I would imagine that the Graduate school you are studying at should have these extensions. Check your toolbox and try to select the tools in the Spatial Analyst tool. Then let us know if you can or not. – whyzar Feb 14 '17 at 17:47
  • If you don't have access to a Spatial Analyst license, QGIS (which is totally free) also has a Zonal Statistics feature available. – Dan C Feb 14 '17 at 17:50

Zonal Statistics as Table is the ArcGIS tool you will need. You can use polygons or raster data as your zones.

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In answer to the commented question on 'How can I get a Spatial Analyst license?' you do the following:

  • Open ArcGIS Desktop
  • Under the Customize tab, choose Extensions...
  • down the checkmarked list, you will see Spatial Analyst
  • check the box to enable the extension

Of course, once the extension is enabled, go review the Zonal Statistics feature as described by others in the above comments and go here to review the online documentation on this feature.

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