Obj export does not show the mesh in zbrush

Started by Tokmyra, October 05, 2021, 12:10:10 pm

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Tokmyra

I'm having an issue showing the mesh in zbrush after a render export of an obj file.  It says the points and polygons are there but there not visible at all.  I tried all kinds of stuff in zbrush to get it to show with no luck.  That will be one of the biggest things I need.  I really don't want to go back to vue because I like how Terragen does most of its terrains.  I tried flipping faces and everything else.  I got nothing to work.  I looked through the forums and didn't see anything on it.

Thanks

digitalguru

I don't use Zbrush, but it may be the exported obj has many duplicated vertices and Zbrush can't handle it.

Try to delete the duplicated vertices in a DCC like Maya or 3ds Max - Meshlab is also good for this and is free.

If you exported the obj in a render with multiple threads you will also have duplicate faces you will have to delete.

Zbrush may also not like meshes without UVs, so it could be an idea to select that option in the Micro exporter also.

Tokmyra

I took it in to Houdini and I could see the mesh.  As a test I only made it 65k micro polygons.  Even after cleaning it still was not visible.  I also tried to use an FBX and it had the same issue.  zbrush can handle billions of points, so double facing should not be an issue.  So I did an extrusion in Houdini and the extrusion worked accept for the original mesh. It still didn't show.  I asked a friend of mine to check it out in Maya and he could not see it either.  I've tried it on 2 differnt computers.  Not counting the friend of mine.  It's almost like all the points are invalid.  Tomarrow I will double check the double faces, and duplicate verticals.  If anyone else that uses zbrish figure this out, please let me know.

Thanks

Dune

Did you try Dynamesh? With enough resolution that would probably eliminate all double faces, as it's a quite rough method of remeshing. Any UV will be gone, however.

Hannes

Or maybe try to load it into Pose Ray. If it's visible, go to Groups, hit "recalculate normals" and resave it. No idea, if this works, but since Pose Ray is free, it's worth a try.

digitalguru

How big is the mesh? If you can, post it somewhere and I can take a look.

digitalguru

October 06, 2021, 08:29:18 am #6 Last Edit: October 06, 2021, 08:41:45 am by digitalguru
Quote from: Tokmyra on October 05, 2021, 08:04:12 pm
Quote from: Tokmyra on October 05, 2021, 08:04:12 pmI asked a friend of mine to check it out in Maya and he could not see it either.
That seems odd, If you can, post the Terragen file that created it and I can take a look.

Or if the mesh is not too big, post that.

Also, you could try exporting the terrain as an .exr displacement map and bring it into Zbrush that way, Depending on how you generated the terrain, there are various ways to do that. I can post an example scene if you want to go that route.

WAS

October 06, 2021, 12:31:49 pm #7 Last Edit: October 06, 2021, 12:57:20 pm by WAS
Follow these directions to clean-up TG objects: https://planetside.co.uk/forums/index.php/topic,29061.msg286624.html#msg286624

Last step allows you to decimate the object to a desired range that still holds most the detail, but won't kill renderers. 3rd step works best with small holes, tears will just have their borders cleaned.

Example: This very high definition Mars is from Terragen, cleaned up in Meshlab. The original mesh was almost 3gb I believe. It's now 1.5gb.

Screenshot_84.jpg MarsHiPolyObject.jpg

The real killer is your system. I only have a Ryzen 2600 and 32gb of RAM. To handle this model, I actually had to install Razer Game Booster, and launch Gamer Desktop where it suspended almost all Windows services, including Windows Desktop Manager leaving only MeshLab as the only thing visible. Otherwise I kept crashing with filters. This took Windows nearly 8gb of allocated RAM down to 1.8gb, and also kept CPU pretty much completely idle save for MeshLab.

Tokmyra

@WAS 

I will try that in Houdini, I followed the blender post and I can do it just as easy.  I would think if your doing an object export.  The object would be more solid.  That is a lot of work to just use the mesh.  I am going to try the .exr file as well.  Thanks all for all of your help.

WAS

October 06, 2021, 03:08:51 pm #9 Last Edit: October 06, 2021, 03:20:35 pm by WAS
Quote from: Tokmyra on October 06, 2021, 01:59:10 pm@WAS

I will try that in Houdini, I followed the blender post and I can do it just as easy.  I would think if your doing an object export.  The object would be more solid.  That is a lot of work to just use the mesh.  I am going to try the .exr file as well.  Thanks all for all of your help.

The object being exported is being exported from the buffer so to speak, so it's only exporting what the renderer can see and calculates within Terragen.

PS Matt is working on this aspect of TG, and at some point we will have better object exporting, including textures.

digitalguru

Quote from: WAS on October 06, 2021, 03:08:51 pmThe object being exported is being exported from the buffer so to speak, so it's only exporting what the renderer can see and calculates within Terragen.
To add to Was' comment, if you export the terrain from the same camera you use to view the terrain (i.e. a perspective camera), you'll get holes where the camera doesn't see the terrain.

If you create a new camera (and a new render node to handle the export) make it Orthographic and point it down over the terrain - you'll get a terrain with no missing sections in it.

Dune

Quote from: digitalguru on October 06, 2021, 03:53:34 pmif you export the terrain from the same camera you use to view the terrain (i.e. a perspective camera), you'll get holes where the camera doesn't see the terrain.
But if you then import that 'holed' terrain object and render, it shouldn't make any difference in the image. But it will save render time. A bonus, especially with reflections,  much small displacements, and PT.

WAS

Quote from: Dune on October 07, 2021, 02:05:39 am
Quote from: digitalguru on October 06, 2021, 03:53:34 pmif you export the terrain from the same camera you use to view the terrain (i.e. a perspective camera), you'll get holes where the camera doesn't see the terrain.
But if you then import that 'holed' terrain object and render, it shouldn't make any difference in the image. But it will save render time. A bonus, especially with reflections,  much small displacements, and PT.
That assumes you're rendering from the same perspective somewhere else, and not just using TG as a working camera. Additionally, never noticed much difference in render time between perspective and orthographic when everything is turned off and set up for a export. A perspective object is basically useless for anything other than the perspective. And for something you may use somewhere else, even later down the road and want to redo, you can't just change the perspective, it's a destructive "format" which doesn't make sense in todays art world of preserving things to do differently.

Dune

No, that's right of course. But if you just want to speed up PT render time for that one particular view, it's a method. But only if it's really worthwhile, because making such an object also takes time. I probably won't us it very often.