Transfer vertex position via UV coordinates

Hammers · April 23, 2018, 9:50am

I just came across this interesting technique to help retopologise complex geometry - in this case cloth from Marvelous Designer.

Especially the step involving transferring vertex 3d position to the low poly flat retopo object via its shared UV coordinates with the hi-poly object was very cool. Using that to basically warp the flat plane to conform with the hi-res cloth.

I was just having a look to see if this would work somehow in Blender - I thought maybe the data transfer modifier might work, but no luck so far.

Has anyone ever done this in Blender? I wonder how hard this would be to create a script for…

SterlingRoth · April 26, 2018, 9:12am

Hm, that is interesting. I know you can get the object space coordinates via the object info node in cycles. You could bake that out and then use the displace modifier to offset the geometry on your low-poly model. On initial testing it seems like there is potential. I think the scripting aspect might be very complicated, especially cutting the topology of your low-poly object to follow the curves of the high-poly object.

Hammers · April 26, 2018, 9:12am

Ah info nodes, that’s an interesting thought, I might have a play with that. As per the example, if the low-poly object were created manually, perhaps the scripting might not be as daunting, and perhaps it could become an extension of the data transfer modifier even.

I speak only with complete ignorance of all things scripting and coding

Hammers · May 1, 2018, 6:16am

OK so I’ve made some progress, but just not quite there. I used a geometry node on my test mesh (left), and baked the emission texture (as 32 bit exr). Then I applied that to my lower res mesh grid with a displacement modifier using RGB to XYZ.

It’s very approximately the same shape but not really as precise as I’d hoped. Does anyone know how this inaccuracy is happening, or how to get a closer result?

Is there possibly a bug in either the geometry node position (seems unlikely…), or the displacment modifier? This is what it looks like from checking rgb values vs vertex positions on the displaced object…

So near I can almost taste it!