[balt]

Hi all,

I'm assigning a volumetric tag to the null object (I'm in Cinema 4D) and when I do that, the fire preview shows volumetrics as expected. When I render the same view however, I get bands of black, (as if looking through window blinds) rendering in front of the scene, at SL 3, the entire screen is black. From SL 1-2, I can still see that it is the correct scene that's being rendered behind the encroaching black slits. Bizarre. Anyone else see this behaviour?

Edit: I should add I leave all settings on default, and use a "constant" field type with density 1.

Cheers

- Balt

[Mihai]

What kind of material do you have applied to it? Second, please do a test by opening the resulting MXS the plugin creates in Studio and render from there to see if you still get the bands.

[balt]

Hi,

Thanks for taking the time to respond. I'm not a 3D pro, so this may well be due to problems with my scene or my understanding of how things are meant to work. I've created a test scene in C4D, download from here: http://www.inside.net/VolumetricTest.zip

The null object has no material assigned, only the Maxwell Volumetric tag is set.

The expected outcome is to see a cube of light fog encompassing the central cube in the image. Do you agree with that?

The actual outcomes are:

- Rendering in fire in C4D produces a dark cloud (not a white cloud).
- Rendering straight to Maxwell from C4D renders just a completely black screen.
- Exporting to Studio renders a dark cube in Fire (same as in the C4D fire), but just all black in Maxwell render (same as when rendering out of C4D).

Deleting the null object in studio and adding a volumetric there (Create extension object -> Maxwell Volumetric) and moving it into the area where the old one was:
- renders dark cube in fire as above
- renders the black blind effect in Maxwell render, i.e. blinds to SL ~3, then completely black.

(now here's the fun one):
- resizing the volumetric then makes it render the cloud in white as expected.
- sending it to maxwell render from there still produces just a black screen.

Can you reproduce this behaviour?

Thanks

- Balt

[balt]

I also just found out that by changing the order in the scene tree, the fog renders dark again. Then go and click on the materials in the scene (not doing anything with them, just clicking on them in the Materials list) and the fog turns white again… Strange things happening!

Cheers

- Balt

[JDHill]

The expected outcome is to see a cube of light fog encompassing the central cube in the image. Do you agree with that?

Not really; Maxwell falls back to using a default MXM, but I've generally seen extensions (i.e. grass, volumetric, etc) not use that and render with "no material" instead, which I do not think is a stable rendering state. So please assign a material, even if it is just whatever gets created when you initially create a new one, and see if that helps. You need a material anyway, if you want to be able to control how the volumetric looks.

[balt]

Ah! Adding a material to the null object (and the volumetric tag) appears to solve this problem.

Cheers

- Balt

[shen.de]

one question from me... i can render volumentrics wihtout material. a material doesnt seem to change anything. smoke material on a cube does.

but beside that when I add volumentrics tag on a null object it doesn't show the boarders of it in the viewport unlike it does for sea or render-region f.e.

anyone experienced that , too?

[JDHill]

Does it do that even with the simplest example (just one null with a default Volumetric tag), or just with particular models? The only ways I know to stop the Volumetric tag drawing its representation are:

• 1. By disabling View Settings > Filter > Null.
  2. By using Field Type > Particle, and not assigning a valid particle file.

[shen.de]

you were right JD. null was set to invisible. shame on me ^^

[JDHill]

No worries, I prefer false alarms to bugs. :)

[3dtrialpractice]

so this is specifically related to cinema4d ?

[JDHill]

Yes and no -- the general advice to make sure and apply a material to a volumetric is not plugin-specific.