Houdini Vray Pyro Bounding box shadow

[lear_lilko]

Hi,
I'm using Houdini Indie with Vray 6 RTX with a 4080.
Pyro Solver->Pyro Bake Volume->Pack->Material Node (Vray Volume Grid Shader)

Hi, I'm having is weird thing happen.
The pyro container box seems to be casting a shadow after rendering between 6 and 9 frames. (See black line in lower left corner). If I interrupt the renders and re-render the frame it's gone (See line is gone in left image after stop and start). If it let it go, eventually the whole frame is dark like a heavy overcast square (see second attached screen capture).
I have shadows turned off on the smoke because I thought that was the problem. I tried brute force GI.
Anyone had this happen?

[tsvetomira.girginova]

Dear lear_lilko, hello.

Could you please paste here the information from V-Ray > About V-Ray?
There is a Copy to Clipboard option.

In addition, what Houdini version you are using and on what OS?

Since you are posting this in V-Ray GPU forum section, is the issue not visible if you perform a CPU rendering?

Waiting for your answer.

Best regards,
TS

[lear_lilko]

About Vray -
V-Ray for Houdini hash:20a9711 from 12 Dec 2022 21:57
V-Ray Core 6.00.21 [cf284949] from 10 Dec 2022

Using Houdini Indie 19.5.605-Py3.9 on Windows 11, i9 with 4080GPU 128GB system ram


I set CPU to render now to see if problem occurs, but it may be some time to render 8 frames. GPU is 100+x faster. Yes, GPU is <1 min per frame. CPU is 20min per frame. So It may be several hours before I know. I will post back then. Thanks for your help.

[tsvetomira.girginova]

Thanks!

I totally understand, but will be beneficial to isolate is it a GPU issue or not.
Will also advice to use our latest stable builds, available here: https://nightlies.chaos.com/main#/vr...e/6.0/20230506

Please confirm are you seeing the builds in the added above link or should I request access for you.

[lear_lilko]

Hi,
It rendered perfectly with CPU. No shadow issue.

[lear_lilko]

Just FYI, the problem is consistent across files.
This is a completely different project with a flame, Same thing. After a bunch of frames the pyro box starts casting a dark shadow. Stopping the render and re-rendering the frame gets rid of it for about 10 frames.

I was hoping maybe this happened to other people and it would be a setting or easy fix. But I guess not?

[lear_lilko]

Hi, Solved.

I bypassed the PyroBakeVolume node and it works fine now.
Looks like it only needs the pack node. One of those Houdini Gotchas.

With the PyroBakeVolume node on, the volume just build it up frame after frame almost like trails until it got dense enough to cast a shadow which just got darker and darker.
you can actually see the effect. I though maybe that was just my substeps but no, it's the volume building up frame after frame.

So this is solved. thanks.