Aggregate (Spatial Analyst) outputs the same values whatever statistic is requested

DavidKidd2 — Tue, 05 Mar 2019 12:08:58 GMT

I am experiencing a problem using the Aggregate (Spatial Analyst) tool in both ArcGIS Desktop 10.6.1 and ArcPro 2.2.1 to calculate statistics for generalised raster cells.

I have a 1km resolution DEM from which I want to calculate the MAXIMUM cell value within the cells of a 5km raster. The origins of both rasters are the same.

My simple test data set (in Aggregate.gdb) is a 5x5 1km2 elevation grid (ScotDEMCellAOI) with values as follows:

OBJECTID	Value	Count
1	456	1	456
2	459	1	459
3	460	1	460
4	466	1	466
5	488	1	488
6	489	1	489
7	496	1	496
8	499	1	499
9	500	1	500
10	501	1	501
11	507	1	507
12	511	1	511
13	513	2	1026
14	521	1	521
15	522	1	522
16	538	1	538
17	541	1	541
18	544	1	544
19	546	1	546
20	576	1	576
21	580	1	580
22	598	1	598
23	599	1	599
24	600	1	600

		Max	600
		Mean	520.92

ScotDEMCellAOI

I wish to aggregate these cells to the coincident 5*5 km cell (CellAOI5km).

I populate the Aggregate (Spatial Analyst) as follows:

The output is a single 5*5 cell with the value 496?

I get the same output when I try and calculate other statistics?

Am I doing something wrong?

Re: Aggregate (Spatial Analyst) outputs the same values whatever statistic is requested

JuanLaguna — Tue, 12 Mar 2019 02:24:51 GMT

Hi David.

It looks like you set the Cell Factor to 1 and the Environment Cell Size to 5000 (m).

I think if you try setting the Cell Factor to 5, and leaving the Environment Cell Size to the default (or 1000m), you should get the results you're expecting.

The intention of the tool is to produce a coarser (reduced resolution) version of the input raster, with the multiplier specified by the Cell Factor. In the scenario described above, the input is essentially being resampled to the 5000 m resolution first, before any statistical option is applied.

Hopefully this resolves your issue.

Cheers,

Juan Laguna

Spatial Analyst Team, Esri

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Aggregate (Spatial Analyst) outputs the same values whatever statistic is requested

Re: Aggregate (Spatial Analyst) outputs the same values whatever statistic is requested