View Full Version : Volume Caustics

02 February 2005, 09:07 AM
Had anyone any luck on creating volumetric efects with parti_voulme shader?
Or what the hell does that raymarcher voulme shader?

02 February 2005, 03:21 AM
I was just about to start a topic on this because I've been playing around with volume caustics and the parti_volume shader and I have some images and animations to show:

(GI, FG and Caustics)

The same but with thin fog and volume caustics.

Thicker fog.

The volume caustics isn't THAT obvious in those images. The last image with thick fog took 32 minutes to render on my 1.5ghz computer. The thin fog image took much less, and the one without fog was only like 3 minutes or something.

Here's an animation (not of that scene) with really obvious volume caustics:

And here's just an animation of normal caustics with a morphy object and material to see if the caustics would stay sharp, and they did!:

I'll post the scene of the volume caustics animation in a few minutes! It's for Maya 6.5 though. :(

02 February 2005, 03:35 AM
Yes! Finally been waiting for someone to show some Volume Caustic stuff with 6.5, I have been having problems .. I posted here just recently..

So I guess you answered some of my questions. ;) Would love the Maya Scene for this animation!

02 February 2005, 04:16 AM
The Motiondesign tutorial (which is where I first learnt how to do it ages ago) actually has some extra stuff in it that you don't need, and one of the extra things he turns on is what stops it from working in 6 and 6.5. He turns on 'No Globalillum where direct' (or whatever it is) on one of the nodes which is what messes it up. That option means "don't do volume caustics or volume GI where there is direct lighting" (I think!) and so because he has like 3 lights in that scene that light up the whole room with direct light, it doesn't do anything!!

If only I knew that back then I might have thought "hmm he's not as good as I thought" and then I wouldn't have ordered his phantom DVD.

Anyway! A scene is attached. It's not 'quite' as cool as my original one because I used the l_glass shader before, and most people probably don't have that installed. The attached scene uses a dielectric shader instead. The l_glass shader is really very nice (I'm using the version 2 beta) and the scene using it took about 1 - 1.5 minutes a frame to render, whereas the attahced scene takes me 1.5 to 2.5.

The only parameter that affects things on the "photon converter" object is the extinction on the parti_volume_photon. It affects basically how "far" the volume photons will travel before they get used up. All the parametres of the parti_volume on the "volume container" affect the rest.


02 February 2005, 11:11 AM
eea jozvex thanx for the scene, I'll try to look over it in maya 6. I've also looked at that volume caustics tutorial from motiondesign, and yeah, I've opened their scene and when I rendered there was NO volume caustics like in their images. So to make-it work in maya 6 I have to unselect 'no GI where direct' ?

anyway how do you use the raymarcher volume material? cuz it's the only volume-shader I don't know how to use...

02 February 2005, 02:21 PM
Thanks for the scene Jozvex. Nice images. I have also been playing with l_glass and caustics, but have not been happy with the shadows. I have been experimenting with hooking up shadow shaders - not too successful yet - so I was wondering if you had worked out any techniques to get more realistic looking shadows.

02 February 2005, 12:55 AM
Well in my images posted above I used the shadow shader along with the l_glass. It seems that you need to set the Mode of the shader to 1 for it to work, and that you need to set the transparency quite high for it to even start looking transparent.

That actually may not be true anymore in 6.5. I've just been doing it the same way as I did in 6.01. I think the shadow shader makes it look better than just solid shadows, but it still isn't that great. Maybe it would be nice if you could soften the shadow via the shader? I dunno.

The interesting thing I forgot to mention before though, is that in my volume caustics animation shadows aren't even turned on! The volume caustics just creates "shadows" on the walls by itself!!

Dr. Ira Kane
02 February 2005, 01:22 AM
Cool stuff Jozvex !!

08 August 2005, 03:13 PM
I found that motiondesign tutorial a while back but I've since lost the link - please please can someone post it up for me? thanks :D

I found the motiondesign tutorial above but this isn't the one I were thinking of.

the tutorial involved a glass ball and the light rays refracting thru it and bouncing off another surface - really quite powerful stuff - If anyone knows what I'm on about a link would be really cool cheers


08 August 2005, 08:28 PM

08 August 2005, 02:14 AM
Im a total Newbie to Rendering, and Im poor, where can I learn how do make stuff like that?

I assume I would need to use a special shader to make the glass, but the way lights and shadows behave are a total *whoosh (waves hand over head)* to me.

Im not asking for any specifics, just some info to make rendering more realistic.

btw, how long did it take you to render those animations!?! :o

08 August 2005, 07:08 AM
pichu - your on the site to learn all about it mate - you just gotta dig and dig as the questions have been asked before - pick up the manual - try stuff out and play about dude - theres no 'formatCdrive.mel' command on maya's shelves haha :p

08 August 2005, 07:57 AM
btw, how long did it take you to render those animations!?! :o

I have no idea unfortunately because it was quite a while ago that I made them. I'm not really the sort of person to render for 20 hours (or even 2 or 3 usually) just for testing something, so you can assume that it wasn't terribly slow. :thumbsup:

You can download one of the scene files in my post up above and render it yourself if you like! That is if you have Maya 6.5 or later.......and that it's not Maya PLE.

If you need it in PLE format I can knock that up for you I think!


08 August 2005, 11:09 PM
pichu - your on the site to learn all about it mate - you just gotta dig and dig as the questions have been asked before - pick up the manual - try stuff out and play about dude - theres no 'formatCdrive.mel' command on maya's shelves haha :p

Awesome. I have yet to realize the full potential of this site... So many assignments, so little time to sleep.

08 August 2005, 11:18 PM
:applause: unbelievebaaahh!gee, how did you make that?everything i get after 3 hours of trying to set up the parti was a couple of weird messages- i started a thread about that!gee, :buttrock:

08 August 2005, 01:06 AM
:applause: unbelievebaaahh!gee, how did you make that?

2 cups of plain flour
1 1/2 cups of water
1 cup of sugar
2 egg yolks
Mix for a very long time!

Hehe, no I really just used the tutorial from as a starting point, fixed the problem I mentioned a few posts up, and then tweaked it all into those scenes.

By the way, if people think that I suddenly wake up in the morning and go "Volume Caustics today!!" and then create one of those images straight away, it's not true at all. Well, NOW I could do that perhaps, but there are lots of trial and error scenes that I make that end up not working.

I just don't post those ones of course!!

12 December 2005, 05:32 AM
Does anybody know why Jozvex's scene no longer works in Maya 7 ?

[EDIT] Just figured it out. Add a Parti_Volume_Photon shader to the Volume Container SG Phot Volume Shader input.

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