VDB From Houdini Into Modo

[Mnoloconic]

Hi guys,

For days I've been hunting around the web and following tutorials with no luck what so ever. Modo crashes whenever I import a vdb from Houdini using the V-Ray Volume Grid. I read about changing the Houdini .env file and I tried that by opening up the .env file and typing a line with HOUDINI13_VOLUME_COMPATIBILITY 1. I then exported the vdb following a few tutorials to verify the process. I was wondering if anyone could shine some light on this. Cheers

[vladimir.nedev]

Can you send me that VDB file, so I can check where it crashes ?

Greetings,
Vladimir Nedev

[Mnoloconic]

Well it?s any I load from Houdini. I will send you something tonight . Thanks vlad.

[Mnoloconic]

I emailed you the vdb Vlad. It actually seems to work in modo and modo renderer. Its when I use the volume grid it crashes. As soon as I navigate.

[Mnoloconic]

Im desperate to get this to work. While waiting for the feedback from the vdb I sent you I tried something else. I export the clouds as a geo obj from houdini and followed the v-ray modo volume documentation but all I get is this smudge looking clouds and a weird shadow across the right side of the render of the clouds as you can see in my screen grab. I'm trying to get the broken up wispy effect I attached the image of but no luck. Played with all the noise adjustments in the beacon noise and I even tried procedural marble and played with those settings. Im at a lose really.
This is all just a test because knowing I can use the volumetric and settings will help me in future projects. Your guidance is always appreciated Vlad. cheers.

[vladimir.nedev]

Modo crashes whenever I import a vdb from Houdini using the V-Ray Volume Grid.

No problem with your .vdb for me. I am on Windows 7. It opens with our Volume Grid and MODO's VDBVoxel. See screenshot.
You reported on the MODO forums that it crashes with MODO's VDBVoxel too, right ?
In that case it might be a macOS issue with the OpenVDB library, that both we and MODO use.
Or it could be an OpenGL issue.

If you can start MODO from the command line with the following flag "-dboff:crashreport", instead of sending a crash report to The Foundry, when MODO crashes, macOS will open its own crash dialog, which contains the stack trace for the crash.
If you post that here, I can tell you where the crash is, which could help in solving it.
Boyan will test it on our macOS machine next week.

Played with all the noise adjustments in the beacon noise

To make the clouds more transparent, either increase the Fog Distance in the V-Ray Environment Fog, or decrease Color 2 in the Bercon noise texture.
Also, enable Scatter GI in the V-Ray Environment Fog.

Boyan made some pretty cool looking clouds a while ago, maybe he can share.

and a weird shadow across the right side of the render of the clouds

I don't know what that might be.

Greetings,
Vladimir Nedev

[Mnoloconic]

Hi Vlad, Thanks for the guidance. I copied the text from the crash report and attached it. The VDB works fine in Modo and the Modo renderer. It crashes in V-Ray when using the volume grid.

[vladimir.nedev]

Yes, indeed, it's the OpenGL preview that crashes. Can you try updating your graphics driver ?

Greetings,
Vladimir Nedev

[Mnoloconic]

Ok Vlad,

I made sure my drivers were up to date, which they were. I unplugged my external Cintiq and my egpu and tried to just use my MacBook Pro. It crashed.
Then I loaded in the vdb through modo's schematic via the volume and vdbvoxel nodes and then did a render in modo preview. Everything was ok.
Then I turned off the visibility of both the volume and vdbvoxel in the item list, added a v-ray volume grid and loaded the vdb. It was fine and I was able to navigate and render.

I connected my setup with egpu, and tried again with the same procedure and it worked So for me I have to load it through modo with the volume and vdbvoxel item first, then I can hide them and do the v-ray process. Thank for all your help

[vladimir.nedev]

I don't think loading through MODO's VDBVoxel is what fixed it.

More likely disconnecting and then reconnecting the external GPU somehow fixed the issue.
Maybe my DrawArrays call (it's in the crash report) was somehow going out to the wrong GPU and causing the crash in the GPU drivers that you see.
To be honest, I have no idea how to fix something like this or whether it's fixable on our side at all.

Greetings,
Vladimir Nedev

[Mnoloconic]

Nope, its doing it again. It was working great last night Ive got in touch with the guys who made my egpu to see if there is something I can do with how my connection are set up. Maybe boyan might throw in his few cents within the week.

[boyan]

Hey, Greg.

Thank you for the feedback. It seems problem has appeared within MODO 11++ releases. I think the problem is correlated somehow with OpenGL because crash happens when volume grid visibility is enabled.

I will log the behavior to our system. Meanwhile, a nice and fast workaround for the non-animated scene is to use "Freeze Mesh" command with Modo VDB, and next V-Ray Environment Fog with Gizmo.

I will try to add and some enhancements for cloud rendering as well. Maybe tomorrow.

Cheers,

[Mnoloconic]

Ah great to at least know its not my machine. Thanks Boyan

[Mnoloconic]

Hi Boyan, any luck with some enhancements for the cloud rendering? PS will I be able to use the various parts of a vdb, i.e. fire, smoke if I freeze it? Thank you for all you're troubles.

[vladimir.nedev]

PS will I be able to use the various parts of a vdb, i.e. fire, smoke if I freeze it?

No, you won't.

You could try disabling the OpenGL preview (before loading the VDB) to avoid the crash.
Not sure if that will help.


Greetings,
Vladimir Nedev