Since you’re looking down for 3D Mapping, don’t need ND Filter do you ?
You shouldn’t usually need an ND filter. If it is a bright day and you’re mapping something like snow it could help.
Will having an ND4 from PolarPro affect the results of the photogrammetry in any way?
It shouldn’t have too much affect, but if you have issues with exposure for some reason it could help.
There should be almost no reason to use an ND filter for mapping. An ND filter slows the shutter speed of the camera down by reducing the amount of light available to the sensor. This is helpful for video work, enabling you to match the shutter speed to double the frame rate you are shooting in, ie: 50fps = 100 shutter speed. Use a clear filter for protection of your lens - that’s about all you should need here.