I have a polygon featureclass that I am trying to convert to raster format at a low bit depth (i.e. <8 bit unsigned). The FC contains 50,000 polygons which have five values: 1,3,5,7,9. I have set the value field to record the previously described values. I have also tried adding a field populated with 1's and setting the Value Field to that. The output raster is an 8-bit unsigned raster dataset with a NoData value of 255 every time. I have tried changing the Environment setting > Raster Storage > NoData to every one of the options from NONE to PROMOTION. I have even tried entering "0" as a NoData value in the environment setting. I am pretty sure the tool does not honor that Environment setting.

How can I control the bit depth of the Polygon to Raster output? Preferably I would like a 1, 2 or 4 bit raster output. Work-arounds welcome too.

Edit: Unfortunately, Copy Raster is not an option because the Polygon to Raster conversion is an intermediate step in a larger processing workflow. Creating a new raster dataset would only add more time to the workflow.

  • 1
    have you investigated using the the numpy array functions from the da module on your raster to change the bit depth? Since it is an intermediate step, all of this could be done in memory, given enough RAM.
    – Paul
    Jul 3, 2014 at 18:08
  • @Paul That is a really good idea that I have not investigated.
    – Aaron
    Jul 3, 2014 at 18:10
  • Let me know if you find anything out. I'm toying with vectorizing rasters with numpy arrays and I'd be curious how the inverse works.
    – Paul
    Jul 3, 2014 at 18:15

2 Answers 2


Looking at the help for this tool, bit depth is not an environment setting accessible to this tool. You can use the Copy Raster tool to change bit depth of an existing raster.

  • Thanks Hornbydd. I'm aware of Copy Raster, although it is not an option in my processing workflow as it would add more processing time.
    – Aaron
    Dec 14, 2013 at 18:12

After much research into the subject and even a discussion with ESRI support staff, I am afraid to report that there is no out-of-the-box solution for controlling bit-depth using the ArcGIS Polygon to Raster tool. However, Erdas Imagine has the functionality in the Vector to Raster tool and provides complete control over the output bit depth.

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  • Looks like the same is true for arcpy's NumPyArrayToRaster method. Sep 29, 2015 at 22:02

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