For raster overlays, what is essential for both rasters involved?

In raster overlays, it is crucial that both rasters are in the same coordinate system to ensure accurate alignment and combination of the data. A coordinate system defines how the two-dimensional, projected map in GIS correlates to real locations on the Earth. If the rasters are in different coordinate systems, they will not align correctly during the overlay process, leading to inaccuracies in the resultant data analysis and mapping.

While resolution, color scheme, and geographic projection are important considerations in raster data management and visualization, they do not fundamentally affect the ability to overlay raster datasets as much as the coordinate system does. If the rasters are not in the same coordinate system, the overlay process will likely produce misleading results, regardless of how similar the other attributes may be.