Corona Volume grid problems...

[JoachimArt]

Hi, I'm trying to make some clouds you fly through using the volume grid. But I encounter 2 problems.
WHen flying through a box grid, once I reach a certain point inside the cloud just disappear. As if it only renders it in a certain distance. Also if I am slightly inside and move the camera so it should go out at the top, it disappear before its outside the camera angle.

2nd problem is that I cannot move two volume grids inside eachother, they will cause artifacts, you see the boundingbox in the render, so each volume grid cannot touch eachother.

Anyway to avoid these problems, especially the sudden disappearance!

[pokoy]

You've spotted the two limitations of current VDB implementation. Unfortunately there are no workarounds yet, I hope it'll be solved.

[JoachimArt]

OMG! that makes it pretty useless :(

[JoachimArt]

You've spotted the two limitations of current VDB implementation. Unfortunately there are no workarounds yet, I hope it'll be solved.

I assume the same applies to the CoronaVolume Inside volume material as well then?  Do you know?

[maru]

Check out our volume limitations page: https://coronarenderer.freshdesk.com/support/solutions/articles/12000040687
We really hope to have those things fixed asap, but they are super complex.

One workaround for the camera-inside-volume is to place a sphere/cube around the camera and use it as a boolean cutout.

[JoachimArt]

thanks!

I can understand the VDB implementation is super complex :) But I've had such amazing results with it, and suddenly when starting animating I noticed this, which just gave me a taste of amazing and then completely debunked the experience :(

How do I treat the sphere as a bolean cutout for the VDB ? (could you explain please ? ) Is it possible for it to fade away the VDB gradually as you get closer?
Nonetheless using large cloud clusters would then never work am I right? because that means the entire cluster would disappear?

[pokoy]

Mary, I'm not sure the boolean trick works with VDB volumes... it's the common workaround for volume meshes, but not for VDB afaik. I hope I'm wrong, though.

[JoachimArt]

Mary, I'm not sure the boolean trick works with VDB volumes... it's the common workaround for volume meshes, but not for VDB afaik. I hope I'm wrong, though.

If any of you could explain how to do the boolean trick I would be very interested to hear. Even if it only works for the CoronaVolumes, I'd be interested because also corona volumes aren't exactly reliable when moving the camera through it or adding meshes on top of eachother. (they seem to suffer from many similar symptoms even though VDB have bigger more obvious problems.)  Also adding a VDB inside a coronaVolume causes a lot of issues.

It would gave been an awesome feat (!) if both CoronaVolumes And VDB volume grids would just seamlessly work no matter how you mixed and matched and overlapped. That should really be one of the plans for the upcoming release or the next, if v3 on is about to enter final release. Because it's such an integral part of the renderer and with full freedom you can do amazing stuff with a lot more control, if you don't have to try to avoid artifacts like this.

[Njen]

I've done this quite successfully here:
https://forum.corona-renderer.com/index.php?topic=20183.msg128657#msg128657

It's quite simple, make sure you have a water-tight geo, then simply boolean a very small sphere at the pivot point of the camera.

For extra points, keep it as a live compound object, then wire the translation parameters of the sphere compound subobject to the translation of the camera, and it then all works automatically for an animated camera.

[JoachimArt]

I've done this quite successfully here:
https://forum.corona-renderer.com/index.php?topic=20183.msg128657#msg128657

It's quite simple, make sure you have a water-tight geo, then simply boolean a very small sphere at the pivot point of the camera.

For extra points, keep it as a live compound object, then wire the translation parameters of the sphere compound subobject to the translation of the camera, and it then all works automatically for an animated camera.

Those images from your movie looks really great!

Thanks for the tip. that's a very useful one for VolumeMaterials.  But, if this is the technique Maru suggested I dont see how it would work with VDB Volume Grids, since they aren't meshes and can't be booleaned the same way. Care to elaborate Maru?

[PROH]

I believe Maru responded to your question about Corona Volume Mtl. AFAIK this can't be done with VDB.

[JoachimArt]

For extra points, keep it as a live compound object, then wire the translation parameters of the sphere compound subobject to the translation of the camera, and it then all works automatically for an animated camera.

How exactly can you link a booleaned operand to a camera? I'm not able to either link or position constraint the operands to anything.

[PROH]

You can't link the sphere (Boolean operand) to the camera, and personally I never made the "wire-thing" work. But you can animate the sphere and link the camera to it.

[Njen]

You can't link the sphere (Boolean operand) to the camera, and personally I never made the "wire-thing" work. But you can animate the sphere and link the camera to it.

For extra points, keep it as a live compound object, then wire the translation parameters of the sphere compound subobject to the translation of the camera, and it then all works automatically for an animated camera.

How exactly can you link a booleaned operand to a camera? I'm not able to either link or position constraint the operands to anything.

I never said link. But you certainly can wire the translation of a compound subobject to any other object's translation. Just right click on the boolean compound object, then choose 'Wire Parameters', then go to 'Object (Boolean) [or 'ProBoolean] and find the transform for the correct subobject.

I do it all the time and it works perfectly.