Input GIS files inquiry: local vs global projections


This is a kind of GIS inquiry, but I am a beginner so I would appreciate a comment.
Regarding the input GIS files, they are not in the same coordinate reference system, since e.g. the bathymetry, AOI, geomorphology files are 'more locally projected’ for better detail, but the landmass polygon (has to cover a much larger area) or the global continental shelf file (borrowed it from the Grand Bahamas example) are apparently projected in other CRS. The CRS reprojections through GIS software is possible so the files could be in the same CRS but may cause considerable distortions.
Probably it is quite fundamental for more experienced GIS users, but I need to know how crucial is the fact described regarding InVEST model results specifically, and I am interested in any suggestions on the proper file preparation. (Is it mandatory the input files to be in the same CRS? and if so is it preferable to be a world/European one than a local UTM zone?)

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@byron , you’re right that these details matter. Some InVEST models handle things differently, but in general, a model will either A) require all the inputs to be in the same projected coordinate system, or B) use the coordinate system of one specific input and project all the others to match it during the model’s execution.

The Coastal Vulnerability model does the latter. It uses the CRS from Area of Interest and projects the other datasets to that system as-needed. And it even does smart things like first clipping a layer using it’s native CRS, and then projecting it the AOI CRS. So it handles the case where an input, like the WaveWatch3, landmass, etc, has a global extent and therefore the entire layer cannot be directly projected to the local CRS.

It’s never a bad idea to have all your data in the same CRS before running any invest model, but in the case of Coastal Vulnerability, just be sure you don’t clip any of the global layers directly to the AOI. A buffer around the AOI is needed for many of the layers to have complete coverage for wind & wave calculations, habitat searches, etc. The model will handle all of this for you so it’s perfectly fine to feed in global layers.

Thank you for the answer Dave.

So it does not really matter if the world or european projected files are pre-reprojected and saved in AOI CRS through GIS software, or feed them straight away in the model, they’ll be handled anyways… cool!

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