I have to analyze 8 raster layers, 5 of them are 0.5 degree resolution and the other three are 0.05 degree resolution.

Firstly, should I resample the 5 to finer resolution (0.05 degree) and if possible how to do this.

Secondly, if it is better to resample the 3 to the resolution of the others (0.5), what tool do I use to do this without changing the values of the raster. The 3 fine resolution rasters are livestock count data.

I am using ArcGIS Desktop 10.2.

  • Thanks to both Martin and GianlucaF. I used the aggregate tool to match the resolution of the livestock data to that of the other rasters (0.05 to 0.5 degree cell size). I noticed that the output rasters had cell size of 0.500001, so I used the resample tool with nearest neighbour technique to get this to 0.5 cell size. – veesilouette Dec 1 '14 at 14:27

To downscale to a finer resolution you can change the environmental settings to 0.05 and divide the rasters by ten, just check that your rasters are floating and not integers. On the second case you can use the Aggregate tool, that sums the pixels using a ten factor.

  • thank you so much GianlucaF. Do I just use the aggregate tool on each raster? I have decided to reduce the resolution of the finer data. And please what are the settings I should use in the aggregate tool interface, like what method do I choose for the livestock data (they are counts of the animals/grid cell). – veesilouette Dec 1 '14 at 13:43
  • Thanks again. I used the aggregate tool with cell factor of 10. But checking the output cell size is 0.5000001. How do I make it just 0.5 – veesilouette Dec 1 '14 at 14:13

Resampling a raster to a finer resolution is basically the same as making up data. If you do, you imply that you have more detail than you actually have.

To expand on @GianlucaF's answer, there's a tool called Resample that you can use to change your high-res rasters to match the 0.5 degree ones. There are a number of different techniques to resample. Bilinear interpolation is probably easiest if you have numbers, but try other methods as well. That'll give you mean values of your original cells.

  • Okay so it would be better to just resample to match the coarser resolution. But to do this do I simply use the aggregate tool on 3 of my livestock rasters? and what resample techniques is best for them (livestock count). Thanks alot – veesilouette Dec 1 '14 at 13:41
  • You can use the Aggregate tool, with the SUM aggregation type. Look here for further reference help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//… – Gianluca Franceschini Dec 1 '14 at 13:48
  • One more question before I close this, to my understanding the aggregate tool using SUM will add up the values of the merged cells from the input raster. Using a cell factor of 10 will multiply the cell size from 0.05 to 0.5 right? – veesilouette Dec 1 '14 at 13:56

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