Create warning for interpolation from geodata

[krober10nd]

• Altering user geodata may have been downsampled to fit in RAM and it's best to probably just interpolate directly from the DEM.

m = interp(m,'DEM.nc'); 

[HamishB]

just to note, I tried changing the hardcoded AVAILABLE_MEMORY=4 GB size in geodata.m to 100 GB on our big-memory workstation but was still getting downsampling stride messages. Maybe that was just because the DEM is much finer resolution than the minimum element size; is it supposed to be like that?

[krober10nd]

yes. If the DEM is much finer than the minimum element size, then there's little point in reading in everything. I guess we could put some more advanced up and down sampling methods.

[krober10nd]

Just to note: I would strongly recommend not interpolating from the geodata object and instead using the original NetCDF file with msh.interp.

Building a mesh from a geodata object is fine, but interpolation is more critical to get right and sensitive to downsampling.