Zonal Statistics not working for a subset of polygons

[DanielBigelow1]

I have a sample of 531 polygons (taxlots). I am trying to attribute the mean value of a precipitation raster to each polygon in my shapefile. However, when I run the Zonal Statistics as Table tool, I am only getting the desired values for 468 of the 531 polygons. The problem persists if I use Zonal Statistics (not as Table) instead. One thing I've noticed is that the polygons for which I am not getting values tend to be small (i.e. less than a half-acre). Has anyone else encountered this problem before? Namely, is there a threshold polygon size for Zonal Statistics, below which the tool will not work?

I know that as a workaround I could convert the precipitation raster to a polygon and then clip and intersect it with my taxlots, but I don't want to go that route if it's not absolutely necessary. Any help would be greatly appreciated. Thanks!

[curtvprice]

If the extent of a polygon approaches the raster resolution on your precipitation raster, you are going only pick up a few (or no) cells for each tax parcel polygon.

Have you tried setting the environment Raster > Cell Size to be a smaller value than the resolution of your precip raster?

[MarkBoucher]

Also, make sure your processing extent includes both datasets. I've had the processing extent reset to a smaller extent based on a dataset I used in previous processes.

[EricRice]

Your polygons are converted to raster internally at the same resolution of the value raster. Here is the documentation for the tool. Zonal Statistics as Table

Relevant parts:

If the zone input is a feature dataset with relatively small features, keep in mind that the resolution of the information needs to be appropriate relative to the resolution of the value raster. If the areas of single features are similar to or smaller than the area of single cells in the value raster, in the feature-to-raster conversion some of these zones may not be represented.

To demonstrate this, try converting the feature dataset to a raster with the appropriate feature-to-raster conversion tool and specify the resolution to be that of the Value raster. The result from this conversion will give an indication about what the default output of the zonal operation will be.

If you have fewer results in the output than you may have expected, you need to determine an appropriate raster resolution that will represent the detail of your feature input, and use this resolution as the Cell Size of the Raster Analysis Settings of the Environment.

Best,
Eric

[DanielBigelow1]

Thank you. I manually set the cell size to the arbitrarily small value of "2" and it now works. Just as a note, setting the cell size to the minimum of the inputs did not alleviate the problem. Thanks again for the help.