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(Displaced?) Geometry randomly missing on Render to Disk

PostPosted: Sat Apr 13, 2019 6:04 pm
by cliffkm
I've built a scene and set it up to render several frame ranges. The first few frames will usually look fine so I let it go. However usually at some point in the frame range some of the geometry will disappear and sort of create a hole through the scene (see pictures). I have had renders complete without issue but then the next one will get it, so it's kind of random but it is more common than not unfortunately. Once it appears it doesn't go away on successive frames, even with Full Reload on.

It only seems to happen to geometry with displacement but I'm not certain that is the issue. It also only seems to happen on to Render to Disk. I've been unable to reproduce it in the IPR. I suspect this is a bug but I'm fairly new to Houdini and Octane so it could be user error.

Does anyone have any idea how to fix this?

Here are things I've tried to fix it:
- Switch the displacement texture
- Change various displacement settings
- Toggle Update/Reload in the ROP
- Multiple ROP renders, node by node/frame by frame (attempting to force a fresh load)

My system:
1x 2080ti
1x 1080
Nvidia drivers are 419.67
Octane is 2018.1.0.7
Houdini is 17.5.173

I'd be happy to give more details if needed or send the project. I didn't attach it because it's somewhat large.



Re: (Displaced?) Geometry randomly missing on Render to Disk

PostPosted: Sat Apr 13, 2019 9:16 pm
by cliffkm
I saw that there were some new Nvidia drivers released the other day so I'm trying 425.31.

Re: (Displaced?) Geometry randomly missing on Render to Disk

PostPosted: Sat Apr 13, 2019 10:03 pm
by cliffkm
Updating drivers did not resolve the issue.

Re: (Displaced?) Geometry randomly missing on Render to Disk

PostPosted: Sun Apr 14, 2019 5:45 pm
by juanjgon

The problem can be that at some point the object mesh topology changes between two frames, and the plugin can't update the mesh deformations or compute the motion blur. Can you please try to render the scene configuring the ROP node in "Full Scene Reload" mode? This problem should be reported in the Octane log, if you enable it in the plugin options panel.

In any case, if you can't resolve this issue and if you can send me the scene, I could take a look at it to check what could be the problem.


Re: (Displaced?) Geometry randomly missing on Render to Disk

PostPosted: Sun Apr 14, 2019 9:40 pm
by cliffkm
Hi Juanjo,

Thanks for the suggestions.

I had already tried running the render with Full Scene Reload on and was still getting this issue. I went ahead and did it again with debug logging. After the problem occurred I looked at the log and noticed some errors.

I get this one a few times: [materials] --------- Material SHOP node "" not found

If I'm not mistaken this is because Octane prefers the material to be set on the geometry node. I was setting it using material nodes in several places (especially around the danishes/tray). Everything was rendering fine in the IPR so I figured it wasn't an issue. I went ahead and tried to clean these up by exporting items and merging them into their own geometry nodes.

I was mostly able to get rid of the material nodes but one piece of geometry (the jam on the danishes) would not render from it's own geometry node and I have no idea why. Other than that I'm still getting that error from what I believe to be my lights which have no material set.

The other error I get is: [rt vop] ------------ The Octane node has not been found in the linked node

I have no idea what this means or what I'd need to do to resolve it.

Regardless, after cleaning up the material assignment I'm running the render again and so far the issue hasn't occurred. I'll report back once it finishes or if the issue comes back.

Re: (Displaced?) Geometry randomly missing on Render to Disk

PostPosted: Tue Apr 16, 2019 5:05 pm
by cliffkm
Okay, so it did eventually finish and the problem didn't occur again. Unless I accidentally fixed it some other way, switching from material node assignment to geometry assignment did the trick.

I did get several seg faults and crashes during the render, mostly between frames. I'm not sure if this was Houdini or Octane causing the crashes. I didn't see anything new or interesting in the octane logs. And, while they're annoying, it was infrequent enough that I could just pick up where it left off.