I've imported an obj file of Comet 67P here (newly released) and found it has over 4 million polygons. I'd like to reduce that number, but using somewhat "scientific" method/strategy using an algorithm I understand. For example - I would want to avoid alter heights or shadow positions, volume, etc.
So instead of "Just use decimate", could I have a strategy, or some ideas how to approach creating an algorithm which reduces the polygons - by a factor of say between 2 and 10, which maintains peaks, valleys, volume, etc. Maybe something like a "it's pretty flat around here" detector?
Note - monkey added for scale reference.