Optimize UV map after removing geometry

Question

I have a model created via photogrametry. I removed lots of unuseful geometry, but the UV map stays the same, taking a lot of space containing non useful data. I need to optimize the model for the smallest possible size.

Is there a way to optimize the materials so they're only made of the remaining part of the geometry?

Thanks for your help

Answer 1

I never did this in Blender, but the way should be like this:

1.) Make a copy (not instance) of your mesh

2.) Reunwrap the copy(its probably easier if you turn off the textured mode while doing that)

3.) Bake the texture from the old model to the new one. I googled this here hope its still valid / useful

Answer 2

I think a workflow I use can be helpfull for you too. I use 3d scanners instead of photogrammetry, but it can be applicable for photogrammetry and blender. I cannot show my projects due to NDI but what I get from 3d scanner is something like this: https://www.artec3d.com/3d-models/borderlands-cosplayer

This will be the "High-poly mesh".

Then I optimize the scan in Artec Studio to reduse the number of polygons - the result mesh is still messy, but can be processed in software like Blender of 3ds max without putting my PC on fire. However It's still too messy to make a good UV map, so next step is retopology. There are two ways - change existing topology manually or create the new topology above the old one, like in all retopology tutorials. However, I'm too lazy, so I prefer the 1st way if possible. Then I unwrap the result mesh. This is "low-poly mesh" - It doesn't have to vave as less polygons as possible (Actually this depends on what are you going to do with a final model) - but simple enough to make a proper UVs and comfort workflow. Then I bake the color map (that one with messy UVs) and normal map from high poly to low poly. To get more detailed normal map I use as high poly mesh as possible. I use Substance Painter for baking, but you can use blender, if it works good with high poly.