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Export With UV Mapping


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I'm a NURBS modeler.  I am a complete noob when it comes to meshes.  


This is my existing workflow:

--Model in Rhino

--Bring obj file into 3DCoat for voxelizing.

----fix boolean issues with voxel volumes

----smooth all to relax sharp edges giving them a slight bevel


Works great.  I'm trying to take my Maxwell renders to the next level by adding microscopic scratches in high polished areas.  I'm going to set the roughness to a texture map that contains faint scratches.  The problem is I can't get the UV map to export from 3D Coat.  Here's the problem:



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The way you are doing things currently you are exporting two entirely unrelated meshes.

The first one is a low poly version of the object in the Voxel workspace, derived through manual or automatic meshing operation (Autopo or manual Retopo).

If you are exporting this mesh you'll get the UV's you had assigned to that mesh. Note that there's no scale issue - 3DCoat and Maxwell simply use Checker patterns of different size.


When you choose the second export option 3DC exports the surface mesh (it at least in Voxel mode equals the Rhino render mesh) of the object int the Voxel room.

As the surface mesh may be very dense you may reduce its resolution with a slider. The result however will always be a triangulated mesh without UV's. This second exporter may get

used for 3D printing or for shuffling Hi Res geo over to other digital sculpting apps.


What you rather should do is an Auto Retopology with higher polycount target or manually create a denser retopo mesh. You can also use the subdivide function inside Retopo room.

Then you'll get the HiRes version which will export with UV's.


Maxwell V3 will allow you to import the low polygon cages and to subdivide them at rendertime. This however will - as is - only work with geometry as simple as your sample, for anything

more complex one needed textures which re-inject the detail of the original voxel-object at rendertime (displacement/normal maps). One can create these with 3DC too.

Edited by polyxo
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I realized they were separate meshes, but I thought for sure the UV map was applied, or would be applied in the voxel room's case, to the object at export.  


I don't think a low poly workflow would work for me.  For example, I can grow a model @ .0127mm layer height with a 10 to 15 MB mesh.  But in Maxwell, I have to use a 75 to 100MB mesh or else I get a stair step/jagged look in all of my light line reflections.  I can have hundreds of .5mm x .5mm cylinders and lips around stones that would make retopo next to impossible.  I even have to be very careful smoothing a mesh in 3DC that I don't cause a pilot hole for a stone to smooth too much, causing the metal to intersect with a gemstone.  That would ruin the render.


So how does one create a very simply UV map for a high poly object that is ring shaped.  I just wanted my scratches not to have a seam that's rather apparent with box style uv maps.

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No, models inside the Voxel room and its Surface sub-workspace don't have UV's and they also don't inherit those from anywhere else in the program.

Transfering UV's from one mesh to another generally is possible, but only  among meshes with exactly the same topology. Re-using the UV-layout

you created on the quad mesh in the UV-workspace on a decimated triangulated mesh is technically absolutely impossible.


I'm a technical modeller too, so I can understand that you would like to avoid a Low Poly workflow. I don't think though that shading quality could be an

issue - a proper quadmesh should always shade better than all meshes Rhino can create. But remeshing is of course a lot more effort, especially with myriads of parts

and you're neither exporting to a Game Engine nor using the Paint room to create bespoke textures. As Maxwell (which I also use) can handle high polycounts well

one can try a high res workflow.


UV-mapping dense and irregular triangulated meshes from the Voxel room however is by no means as elegant and quick to do as with Low Poly meshes and it's

not exactly a "featured" workflow – most users of this program will have a hard time to understand why on earth you would want to do such...


So here it goes:

Do your thing in Voxel or surface mode, then either export the current object or the whole scene from the file menu. Decimate the level you consider acceptable and

save as .obj without any maps. Re-import this decimated mesh into the UV-Room and create your seams. The UV Path tool will be you lifesaver for this work. Unwrap

(this will be considerably slower now), apply the UV-map and export the model out.

Edited by polyxo
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