1

I am using the Zonal Statistics as Table tool in ArcMap 10.1 to compute the sum of raster cell values (brown scale in below image) in a given set of polygons (red in below image).

Image of what the data looks like

For an unknown reason, the output table is not including all the levels of the polygon file I am trying to get information about. I tried on a smaller set of polygons (as these polygons are buffers) and did not have the same problem. I have indeed asked the Zonal Statistics tool to ignore 'Nodata' (as shown in blue), so I am not sure why this is happening. Suggestions?

Improve this question
2
  • Can you clarify by what you mean by "the output table is not including all the levels of the polygon file"?
    – Fezter ♦
    Mar 14, 2016 at 22:48
  • 1
    If buffers overlap Zonal Statistics is not going to work at all, because ArcGIS converts polygons to raster first. Search this site for Zonal Statistics with overlaps, e.g gis.stackexchange.com/questions/141758/…
    – FelixIP
    Mar 15, 2016 at 0:00

1 Answer 1

Reset to default
2

The standard Zonal Statistics as Table tool does not support overlapping features. This may seem like a bug, but it's a symptom of the fact that Spatial Analyst rasterizes the any vector zone data before processing. Even without overlapping rasters, I tend to run Polygon to Raster myself ahead of time so I can better control cell sizes and snap rasters of the zone data.

Fortunately for you, there is an easy workaround! The Spatial Analyst Supplemental Tools, created by Esri, includes something called Zonal Statistics As Table 2. As described in the blog post:

The Zonal Statistics as Table 2 tool calculates statistics using the values of a raster within zones and reports the results to a table. This new version offers an improvement over the original Zonal Statistics as Table geoprocessing tool by fully handling overlapping polygons in feature zone input.

You should be able to use this toolbox to perform your desired analysis. I haven't used that toolbox in a year or two, so please report back if you have any compatibility issues with Arc 10.3 or 10.4.

Improve this answer
4
  • Great! Thanks for the quick response. This worked great on my version of ArcMap 10.1. Having read the recent comments on the link you provided me with (arcgis.com/home/item.html?id=3528bd72847c439f88190a137a1d0e67) the only thing I'm worried about is if this tool actually calculating all pixels within the polygons or only a portion of them. Thoughts?
    – Dalal_EL_Hanna
    Mar 15, 2016 at 13:33
  • 1
    @Dalal_EL_Hanna If you want confirm, do a spot check compare the results of a few non-overlappping polygons with the regular Zonal Statistics as Table tool to what you get from the supplemental tools.
    – dmahr
    Mar 15, 2016 at 22:53
  • I re created my series of buffers using the <Multiple Ring Buffer> tool as to get all my buffers into the same file. Then, I attempted to use the Zonal Statistics As Table 2 tool to get information on the polygon file with multiple buffers a few times, and everytime, the output does not include all of the objects. Any ideas why this is happenning? I dont think its strictly an overlap problem, as the yielded results (objects it gets results for) are different from the regular Zonal Statistics tool.
    – Dalal_EL_Hanna
    Mar 23, 2016 at 19:58
  • The Zonal Statistics as Table 2 tool is unfortunately not working. A recent comment on the arc blog (arcgis.com/home/item.html?id=3528bd72847c439f88190a137a1d0e67) suggests to edit the Python Code, thoughts on this?
    – Dalal_EL_Hanna
    Apr 18, 2016 at 17:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.