volume grid / VDB geometry transparency issue

[squintnic]

hello
I have got a problem here with using an empty volume grid (y value 0.01 in smoke graph) to make depth haze alongside some VDB clouds loaded into volume grids and when I introduce geometry I get weird cut outs. I have transparency on 1000 and ray depth on 10.
using vray NEXT

any ideas here?

image attached

[squintnic]

I tried with Env Fog and it solved the weird cut out issue but does not seem to occulude the back left cloud in fog properly? Any ideas?

[squintnic]

It works in volumetric geometry mode for the clouds but is so so so slow its not viable for me and needed to increase transperancy to like 4000 ...

[squintnic]

this was stopped after 7hrs while I was away from computer at 1280 x 720...looks correct but that render time is insane...
32 core threadripper

[georgi.zhekov]

Hmm, this sounds like quite a lot. Can you send over the scene so we can profile it?

Thank you,

[squintnic]

Hmm, this sounds like quite a lot. Can you send over the scene so we can profile it?

Thank you,

Yep cool here it is - https://www.dropbox.com/s/ulrwngauy0..._test.rar?dl=0
Just need to relink the cloud VDB with the volume grid

[georgi.zhekov]

In your scene you're using Phoenix FD along with Volume Grid and that's why you need to use Volumetric Geometry mode.

If you stick to only Volume Grid or only Phoenix nodes you can render only in Volumetric mode which should be quite a lot faster.

Note that if you do need render elements you will have to use Volumetric Geomery mode unfortunately.

[squintnic]

Thanks Georgi - to confirm you cannot have a scene that uses a combination of Phoenix and Volume Grids in volumetric mode? Ill test again today and see if I can get it rendering quicker.

[georgi.zhekov]

Yes, mixing Volume Grid and Phoenix FD requires Volumetric Geometry mode.

[squintnic]

Yes, mixing Volume Grid and Phoenix FD requires Volumetric Geometry mode.

Thanks Georgi
It was faster with Volume Grids only - this frame was 1.5hrs on 32 core threadripper...still not great but acceptable...

however I have a new issue now with the volumetric light
As you can see the vray plane lights are showing through the geometry in the volume light casting up when they are occuluded by geometry. it only happens when the clouds are turned on its ok with volume grid haze only. i tried upping the transperancy levels as i thought it could be this but the scene gets an unhandled exception when its at 100

any ideas what this would be?

[squintnic]

I'm getting undhandled exceptions on this when trying to render at 1920 x 1080 at production settings.

The VDBs arent that big (500mb) and there is only one of them instanced around 12 times but the memory use is insane (but still fits within my 128gb - leveling out at about 90gb)
is this expected behaviour? Seems to be the combinations of Volume Grid fog and Volume Grid VDBs that are doing weird things

Im hoping to get this on render farm by tomorrow night to render over weekend!

[georgi.zhekov]

Hey,

Can you try running the scene with the latest V-Ray version? Yesterday we have released an update.

If the issues are still reproducible, please send over the scene as I couldn't reproduce them both in here.

Thank you,

[squintnic]

I cant upgrade the entire farm, will take a while to get the IT systems to upgrade it. Sending over another project with the same issues....

[squintnic]

Ok here is another one with this issue....

I have phoenix smoke sims loaded into Volume Grids but they seem to reveal lights behind occluded objects. This is a new scene has no overall haze like the last one either...stuck for ideas Am I doing something stupid here? Have tried on 2 computers, one older dual xeon and this newer threaddripper using Vray Next update 1.1

There are 2 cameras in this file both doing the same thing, you need to relink that .AUR file into the grid. Can anyone else reproduce it or have trouble with these?

Scene files (should be uploaded in 15 mins)

https://www.dropbox.com/s/n1u1iukzbc...olume.rar?dl=0


resetting the renderer doenst fix it, nor does upping transperancy levels to 5000
interestingly when i switch to GPU it works, but is super slow (2 x 2080 using NVLINK) and I only have a CPU farm to render this one....

[squintnic]

Here is another issue with the older scene (that i still cant resolve...) This has the lights not being occuled by geometry issue but also has an issue with opacity maps which leads me to think its a transparency or ray depth issue of some kind...this render was on 10000 levels of transperancy and still not working (edit and 100,000)

The lights on the buildings are planes with a Vraylight mat with opacity on it - the planes are set to not cast shadows and not affect reflection and are also excluded from the main key light and render fine with just the haze. When you turn the clouds on the building light planes go black and the light sources become visible again...

its driving me bloody crazy, this whole job has loads of smoke and haze and lights