I'm using ArcGIS.
I have a historical map from 1884. It has bathymetry information which I would like to compare to modern bathymetry models with as much accuracy as possible. I don't know what projection to use to retain the best accuracy for comparison.
I've tried georeferencing it once using a WGS_84 projection, and again using a NAD_83 projection for that zone (since this is a small area).Naturally, the map warps differently depending on which projection I've used.
A problem with this map as well, is that I can't space the GCPs very evenly across the raster because the entire bottom half of the map is water. So while I can get the top half georeferenced to fit nicely (using the roads, lighthouses and even some natural features), I'm afraid the bathymetry information will be incorrectly distorted. That's why I really want to choose the best projection.
Which one do you think I should use?
Do you have any ideas on how I can keep this most accurate?