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I am using ArcMap 10.2.2, and I need to aggregate categorical data from 30m up to 90m and 900m resolution for species distribution modeling. The algorithms available in resample (nearest neighbor, bilear, etc.) are not appropriate for my purposes, and the Aggregate tool does not have a "majority" option. Thus, I think I have to use the Block Statistics tool. However, I am getting a strange, recurrent error where some cells in the output raster show up as noData. Has anyone else seen this problem? I got the same effects when working with both fgdb rasters and geotiffs. The same apparently random cells show up as noData over multiple runs. The input data does not have any noData cells in the areas where I'm seeing the problem.

As a work around, I can do this in R using the aggregate function in the raster package. Their algorithm is inexplicably slow, though, and it's more convenient for me to work in Arc if possible. Here are the messages from the results panel, just in case they're helpful.

Messages

Executing: BlockStatistics NLCD_2011_WV_WGS_1984.tif C:\Users\mosteele\Desktop\aggregation_test\NLCD_2011_WV_90m_ArcMap_version2.tif "Rectangle 3 3 CELL" MAJORITY DATA

Start Time: Thu Jun 25 11:45:37 2015

Succeeded at Thu Jun 25 11:45:40 2015 (Elapsed Time: 2.46 seconds)

Input: Input

Output (noData in red):

output


Upon further inspection, I realized that the nodata cells only occurred where there was a tie for majority. I contacted an Esri support person who told me that this is the expected behavior.

I can understand why the algorithm was created like this, but I'd argue that it would be much more useful to have two options - one that would set ties to nodata and one that would, say, break ties randomly. I needed the output surface for species distribution modeling and a version with a bunch of nodata is useless to me. I'm also unsatisfied with Esri's other methods of resampling categorical data, such as the majority option in the Resample tool or resizing by snapping, as they drop a lot of information from the original raster by looking only at a limited window around the centroid of the new cell.

Fortunately, I was able to create the surfaces I needed using R - specifically, the aggregate tool in the raster library.

closed as off-topic by PolyGeo Aug 18 '16 at 8:01

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This problem cannot or can no longer be reproduced. Changes to the system or to the asker's circumstances may have rendered the question obsolete, or the question does not include a procedure to enable potential answerers to reproduce the same symptoms. Such questions are off-topic as they are unlikely to help future readers, but editing them to include more details can lead to re-opening." – PolyGeo
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  • What happens when you do not have majority? when the count between the different categories are even? It might be that those nodata cells are the ones with no majority category. Check the underlying data at the location of these 'random' no data cells. – yanes Oct 13 '15 at 21:40