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So this seems to be an issue because I've seen several questions concerning errors when merging or mosaicking rasters in r, including mine. Sometimes I have no issues merging rasters and others I get the follwing.

Error in compareRaster(x, extent = FALSE, rowcol = FALSE, orig = TRUE,  : different origin

I'm confused because I can go into ArcMap and do the same thing with no issues or I can figure out the differences in tolerance Raster merge attempt, different origin error and set the tolerance accordingly to overcome the error.

So if ArcMap ignores it completely and I can just overcome the error by changing the tolerance what is the purpose of the tolerance at all? Are there any negative effects from increasing the tolerance or can I just put it at the maximum and ignore it altogether?

I couldn't find anything referring directly to what the purpose of the tolerance is and why it is important.

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You cannot simply merge rasters if they do not align. That is, if they have a different resolution and/or a different origin. I believe ArcMap automatically resamples the data to help you out. Well intended, I am sure, but it can also be a recipe sloppy data processing pipelines and for not spotting errors.

In some cases, the differences are very small, perhaps rounding errors that could be ignored. The tolerance setting allows you to define what is small.

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  • But what are the effects of changing tolerance? Say I use a tolerance of 0.5 when merging 100 non-overlapping rasters over the whole Southwest United states? What are the negative effects?
    – Mike D
    Oct 14, 2021 at 16:12

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