Image mapping to high-polygon mesh...

Hi,

I need to apply an image texture to a high-polygon mesh with many millions of triangles, derived from a laser scan. How can I accurately map the image to the mesh, given that unwrapping (even when possible at all) just produces a randomly shaped uv map?

Marking seams is difficult too as it would require clicking along the edges of thousands of triangles.

Any pointers?

Thanks

Us the Smart UV Unwrapping first, to a new blank image. Use the desired Image texture as a Stencil Brush in the Texture Paint mode, and paint it onto the new blank image. Without examples and such, we can’t tell what you are up against of the desired output.

You could also retopologize the current mesh with a new, simpler mesh, and bake the details from the high poly to the low poly as normal and bump maps, and there by do a better job of setting seams and lining up your uvs.

Either way, it involves work.

Thanks Craig. I had thought of the retopology method, but had hoped there might be another way to work with the original detailed mesh. Unwrapping is a problem- just seems to be too complex a job, even for Smart unwrap.
Hey ho…

thanks anyway

Maybe use the Shrinkwrap modifier technique for retopo, it might be faster since you have such a dense model to work with

Although it is possible to do, Blender isn’t terribly well suited for this sort of thing.

Smart UV Project is probably the best option but it is quite slow and with dense meshes you will almost certainly end up with overlapping faces in a few places. Good luck trying to find and fix them by hand, although depending on your texture these problem areas may not be that noticeable. With Blender’s automatic UV tools it is also difficult to reliably get large enough island margins to prevent mipmapping problems while packing efficiently enough to retain adequate texture resolution.

Depending on the specific requirements you may be able to use the UV Project modifier and skip unwrapping entirely, however, it has its own set of limitations.

As painful as it can be manual retopo is probably the best general option. If nothing else it allows you to break up the source mesh and work on small sections at one time in order to maintain acceptable viewport performance.

Yes. Remesh or retopo. Laser scans are messy and wasteful in terms of polys. You’ll need a monster computer to paint it. I would never work with a 3d scan. Chaos.

Those very high density triangular meshes remesh and decimate pretty well In my experience (which only extends to a few) Have you tried that?Better to reduce the vert count make all quads and subsurf than to try to unwrap it.

Haven’t seen your mesh but it’s possible to select shortest path by selecting an edge and then select another one further away with ctrl+RMB (also possible in vertex select mode since 2.68a).
By using the edge tagging feature it’s also possible to automatically mark those selected as seams too. It’s the edge select mode dropdown on the tool shelf.

If unwrapping is possible at all (it’ll take a while for sure), UVProject modifier?
It might be worth checking Meshlab though. There is info on that starting from simple “do 1-2-3” and ending with advanced uses (will add a link later if i find it, sry).

Edit: Close enough

Thanks everyone for these suggestions.

Thanks everyone, for these suggestions.