topic Re: Issues with DistanceAccumulation in ArcGIS Spatial Analyst Questions

Issues with DistanceAccumulation

TrutzBongartz — Wed, 09 Aug 2023 17:07:15 GMT

I've been working on generating potential areas influenced by lava using the DistanceAccumulation tool in ArcGIS Pro. These maps aim to represent lava flow

For the distance accumulation, I've incorporated several rasters:

A surface raster that provides the topographic context. A cost raster derived from slope, indicating the potential pathways lava might preferentially follow. An aspect raster to provide directionality.

The process has been largely successful, and many maps appear accurate and complete. However, I've encountered an issue with some outputs where the representation seems to be arbitrarily truncated or cut off. Interestingly, a visual inspection of the individual rasters at these truncation points doesn't reveal any anomalies or peculiarities.

Has anyone experienced a similar issue or have insights into what might be causing this truncation?

To fully see the problem, please check the images below.

distance acc raster:

Aspect raster

cost raster and topography

Re: Issues with DistanceAccumulation

DanPatterson — Wed, 09 Aug 2023 17:32:41 GMT

If the rasters used in the analysis are just adjacent and not unioned into one, then the analysis extent can't be set to extend beyond the input raster.

If the rasters are indeed unioned as one, then the analysis extent was not set to the proper extent.

All of this assumes that there isn't a single column of nodata separating the two rasters through which distance accumulation can't cross.

Re: Issues with DistanceAccumulation

TrutzBongartz — Wed, 09 Aug 2023 17:53:36 GMT

Hi DanPatterson, I cant follow your reply.

The DistanceAccumulation tool allows me to input aspect, topography and cost as a seperate raster on the same area. I did this for 1000 locations, it went well 950 times. But on 50 times it resulted in these linear cutoffs. So its obviously a tool error and im asking if someone has a tipp how to prevent these.

Sidenote: If I just cut out a single one of the flawed location it works fine. But if I calculate everything at once it results in these errors.

Re: Issues with DistanceAccumulation

DanPatterson — Wed, 09 Aug 2023 20:22:29 GMT

The tool is erroring on an extent issue then and you should forward some of the failed sample data to Tech Support so that the Spatial Analyst team can investigate.