vbd export to ue5

[gao_jian111]

I can't wait to try the new vbd export feature, but when I import the output vbd into ue5 something strange happens. It looks like the exported vbd has no height, the cloud disappears when the camera is level or above the vbd cloud, it seems that the cloud is projected on a plane and can only be seen at a certain angle. I see that the vbd rendered by Kevin Kipper is completely correct. Where am I going wrong?

[gao_jian111]

I lost my original forum account password. I temporarily apply for this temporary account to log in, but it has 1 more than the original account.

[Ariel DK]

I'm really interested in this issue. I personally never tried Vdb export before but im planning to do it in the future, let us know if you find a solution, and hope you can get your old account back

[Kevin Kipper]

Hi gao_jian111,

I'll take a look at what you've described as soon as possible. 

Here's a few things I had to do in UE5 when importing the Terragen VDB asset, to get it to look correct.  Also make sure you're using the VDBResearchActor.

Unreal Engine 5 (Z up)
Requires Sparse Volumetrics, using OpenVDB and NanoVDB plugin and uses a VdbResearchActor as holder for VDB
VdbResearchActor's Rotation X = -90 degrees
VdbResearchActor's Rotation Z = 90 degrees
VdbResearchActor's Scale X = -1
Cinematic Camera Actor Location X = Terragen camera's Position Z *-1
Cinematic Camera Actor Location Y = Terragen camera's Position X
Cinematic Camera Actor Locatrion Z = Terragen camera's Position Y
Cinematic Camera Actor Rotoation Y = Terragen camera's Rotation X
Cinematic Camera Actor Rotation Z = (Terragen camera's Rotation Y * -1) + 180 degrees

[WAS]

Heh, I've seen this issue baked into full on AAA games. Clouds look fine at ground level, but up on a mountain, and you can see they're very thin layers in the sky.

[RogueNZ]

Question, does it have to be using a VDBResearchActor (now called VDBPrincipledActor)? My engine crashes when I try to use this, I'm guessing because I don't have a ray trace enabled card?

Edit: Ok I actually think it was a problem with my VDB export, as I was able to load and render an example VDB provided by Matt a few years ago... back to the drawing board

[Kevin Kipper]

Hi RogueNZ,

Is the engine crashing when you're loading the VDB into UE5 or when you're assigning it to the actor?

I've encountered crashes when I've tried to create a volume texture from the vdb that's successfully loaded into UE5 and believe that is due to a size limitation, something like 2500 x 2500 in two of the axis.  I'm not adept enough with UE5 yet to know all its particulars.

I used the VDBResearchActor because it was recommended when using path tracing.

I'll check to see if there's an update to the Sparse Volumetric plugin.  Thanks!

[pokoy]

@ OP - Can you test how the VDB imports when you move the cloud to 0/0/0 so it is not far away from the origi? Do you see any difference  other than the cloud is in a different position? Does the cloud look correct then?