Scattering.. how to enable ?

[tekano]

thanks for this plugin it has opened up a world of potential and able to circumnavigate Omniverse because of this !

so my issue, Apparently in UE 4/5 there is a Volumetric Advanced Material Output Expression which controls things like phaseG and multiscattering contribution when combined with Volume Cloud Components and sky atmosphere etc. Is there a way to hook this with the current setup or on a VDB actor shader? Ive tried assigning the Fog Shader to the VDB but this scattering Output Expression panel has no effect so far. (it does on the BG sky volume cloud systems though, still digging through the various setups) will try the Path tracing option as well. worst comes to the worst I could bake the scattering into a VDB field from houdini and use like the blackbody setup or similar to get the scattering, but ideally we can use the atmospheric scattering built in.

[thilamb]

Thanks for the kind words !

The Volumetric Advanced Material Output Expression is only used for the brilliant Unreal Volumetric Cloud system.

There is currently no way to exploit this output expression in a VDB actor, but I recently showed how to convert any VDB into a Texture3D https://twitter.com/LambertTibo/status/1511078345425014787

And then how to use a 3D texture with the volumetric cloud system (you don't need the plugin to do this) https://twitter.com/JangaFX/status/1517168910021316608

Let me know if this helps ! Thanks

[tekano]

ah perfect that indeed helps clear up details and had assumed as much so thanks for confirming.. the UE4 Volumetric cloud system is kind of internal format that can also be written to via that 2d slice mosaic image style from Houdini also so was considering that next, pretty handy can just right click and do it directly from the VDB! Whilst it does not support volume cloud sequences like your VDB plugin does (GREAT!) , the multi-scattering for cloud atmosphere rendering more than makes up for this, if they look good I can handle single frames

It was the stringing together of different Volumetric Cloud systems from different sky libraries and sources which was confusing inside of UE5 that will have to study a bit more from the 2nd example. It explains and helps with stringing together say all the 'hero clouds' which is super helpful though.

but now what is unclear is how to add them with a different BG set of clouds from another plugin with its own volumetric Cloud system that already covers the sky as its either one or the other currently not both together with the example above. The volume cloud docs mention some details about masking but its vague and inconclusive and leads to some BP painting system.

Am assuming again there can be only one Volumetric Cloud System at once and I have to figure out how to combine 3D textures from previous BG sky systems with these new recently converted from VDB 'Hero' clouds as demonstrated in the 2nd example above.

this already helps considerably thank you!

[thilamb]

You are right, there can only be one volumetric cloud displayed in a level.

To support both "generic" clouds AND our provided hero cloud example, you simply need to merge those two materials. Copy nodes from the first material into the second, merge everything with a "Max" node at the end, and voila !

Have fun