Hi all -

I'm working on a photogrammetry/LiDAR project and I'm trying to retopologize the model but preserve the basic textures. I've been using the Labs UV Transfer node but I've noticed that node transfers the texture and the UV. But since I'm retopologizing I really just want to project the texture from the scanned model over to the retopo'd model.

Am I over complicating things? Is there a simpler way to achieve this?

Thanks,

Paul

you probably don't want to transfer uvs from photogrametry model

I believe it's more common to create clean uvs on your retopo mesh and just bake the textures or colors from photogrametry

Understood, however I've never before baked anything in Houdini, so I'm not sure where to begin. I'm stuck in my old Softimage brain thinking of using GATOR to transfer things over.

Paul Griswold
Understood, however I've never before baked anything in Houdini, so I'm not sure where to begin. I'm stuck in my old Softimage brain thinking of using GATOR to transfer things over.

You wouldn't be able to use gator for that either
Transferring uvs without introducing seams is not possible for geometries that don't share the same geo seams
Which autouv'd lidar geo with retopo model most likely don't

Regardless, for baking textures between objects you can use
Bake Texture ROP
Or
Labs Maps Baker SOP
Or
Labs Simple Baker SOP

Not transferring UVs. Transferring textures from a scanned object with auto-created UVs from Reality Capture to a retopo'd model with a clean UV set.

We did 22 scans with a Trimble SX-10 and about 3000-3500 photos with Apriltags in them to build out this model and now I need to cut it up into manageable chunks, retopologize and transfer the textures to do a final paint on them.

I think I have it solved now. I chop out sections, build a clean version. Then split the graph where on one side I use UV transfer to get the texture from the scan to the clean version. For the other part of the graph I do a UV unwrap on the clean version (no texture on it). Then I put the clean uv untextured into the first port on the Labs maps baker and the uv transferred version on the 2nd port on the baker and bake the diffuse only from the transferred version to the clean uv version.

This could be the most convoluted way to go, but it seems to work:

Paul Griswold
Not transferring UVs.

Right, for baking there is no uv transfer necessary (I just wanted to clarify that gator wouldn't be useful either as it was for attribute transfer like uv, not for texture transfer like baking)

For baking you just need 2 geos with their own uvs
And it would bake texture for one by sampling the texture of another using ray hits or closest surface etc,

So in your example just bake from your original meshed scan, you don't need to use uvtransfer to the box
Maps Baker uses ray hits or nearest surface (if chosen) to get the location on hi res geo to sample texture from so it doesnt have to be the same topology

Honestly I tried that method and just kept getting a solid white surface. That's why I went the way I did.

There`s no texture input on the labs map baker so how can i tell it what textures to reproject ?

NicTanghe
There`s no texture input on the labs map baker so how can i tell it what textures to reproject ?

it extracts them from the shaders
if you look at the help for the node it outlines the steps, one of them is use Labs QuickMaterial to assign the shaders