Photoscan to Zbrush: Can't create subdivisions

kboruff

Hello,

So I've been getting great results from Photoscan and exporting an OBJ for Zbrush. I'm trying to take the mesh, create UVs in UV Master, send the UV mapped OBJ, get Photoscan to kick out a nice texture, then kick it all back to Zbrush for additional painting and model tweaks. Everything works well, but I've hit a hitch I'm hoping I can work out that is resulting in lower poly models.

Photoscan kicka out a really high quality and polygon count mesh. I take that into Zbrush and if I try to use UV Master the system dies when I hit Unwrap because I've got an insane number of polygons. I tried reconstruct subdiv to get a nice lower level, but the system doesn't create a lower level. I've gone into the geometry palette and made sure to hit merge triangles to quads, close holes, and finally fix mesh and check mesh and it still won't create subdivision levels. I have to use Decimnation master, remesher, or another polygon limiting tool I can't rememeber the name of now to get the poly count down. The low poly mesh now works in UV Master and it's happy to go back to Photoscan for texturing. My issue is that the lower poly mesh has lost a lot of detail.

So, is there a way to make subdivisions from a high polygon mode to alllow for the displacement workflow? If not, is there an alternate means to capture the high res models displacement map and apply it to a lower res model?

Thanks,
Kris

MichaelF

I would try this:
In zbrush, duplicate the mesh, zRemesh it to a some what low count. Uv master, subdivide, project details from the original mesh and export. Now you have a high mesh with the details, subdivision levels and uv's
hope it helps.

gnoop

I just use Photoscan own  mozaik UVs to build textures . Do 16k textures there. Then bring it to Zbrush and do reprojecting to a remeshed mesh with proper UV.  

kboruff

Thanks Michaelf, that seems to have worked fine.

Thanks, Gnoop. I tried that but it caused some issues with texture blurring in the later steps.

My workflow ended up looking like this:

Photoscan to ZBrush Workflow

1. Export model to .obj

(.FBX export with textures works until the end when the textures appear to blur, so I just start with OBJ for cleaning the GEO before worrying about textures)

2. Duplicate Mesh

3. Close Holes

4. Fix any floating ugly bits that were missed in Photoscan's point cloud and trim to what you want here. I trim the model here as well because if you wait it will cause weird issues during projection.

5. Duplicate Mesh

6. zRemesh to lower polycount

7. Setup Polygroups if needed

8. UV Master with Polygroups on

9. Subdivide a few times

10. Project All to bring the original model's details into the current Subtool using the ProjectionShell option to Bubble out the subtool past the higher subdivison mesh

If the details aren't coming through well, undo the project all, subdivide another level and try again. I'm noticing roughly a subdiv level of a million less polygons than the Photoscan import seems to pick up enough details.

11. Export the OBJ of the model at the lowest polycount (In my testing, it appears the higher polycount model takes longer to process withough adding texture detail. Does anyone else have an opinion on this?)

12. Import back into Photoscan, making sure the model is importing into the correct spot

13. Process a new texture with keep UVW's selected. I'm trying to find out if higher res 16k textures really pull more information from photo sources or if Photoscan is just scaling from a set resolution. 16384 is 16k 4096 is 4k

14. Export a .FBX from Photoscan

15. Import .FBX to ZBrush

16. Switch to the Projected UVW correct subtool, not the just imported .FBX

17. Go to the highest Subdivision, select the texture, select the texture imported with the FBX

(I've found that just exporting a texture and importing the texture has alightment issues as doe just using the texture from the FBX. The textures imported with the FBX seem to be aligned properly. I'm not sure why. If anyone has any ideas please let me know.)
Straight texture import:


FBX imported texture:

18. Paint the Texture, clone over any gaps or alignment issues, add any surface sculpting that is missing, smooth any errant polys, sculpt displacement textures

DISPLACEMENT STEPS

19. Go to Highest Subdivide

20. Clone Texture

21. Select texture on left

22. Click Make Alpha

23. Select alpha in Displacement Map on right

24. Click Create Disp Map

25. Go to lowest Subdiv and turn on Displacement and experiment with the levels to see what looks best