regarding volumetric/halo light affects

Hey everyone,

I have a few questions about volumetric lights in blender.

How do I get volumetrics to go away where light is occluded? - There must be a way to do this but I checked the manual and can’t figure it out myself. I want the volumetric light to be occluded by geometry like a shadow map. Right now its just blasting ghostliness everywhere despite whatever shadow setting I have.

How do I have parallel casting volumetrics? What I mean by that is I want my volumetrics to be parallel (like godrays from the sun). I realize the only light capable of volumetrics is the spotlight, but is there a trick to getting some parallel volumetric effects (not diverging from one point).

Any help would be much appreciated.

-Thanks so much.

for your second point
i guess you could add a plane with holes right under the spotlight
that would generates several rays instead of one

hope it helps

thanks for the reply Ricky. However that is not what I mean. I did a poor job of explaining what I meant. I’ve attached a picture that will hopefully clarify my question.

Once I figure out how to occlude volumetrics in the first place (since currently if i place a plane the fog goes strait through it) I want to have parallel shadows, like in diagram i made.


you mean like this see pic

now what about the fog do you stillneed it

you may have to set up 2 spots not certain here what ;s the final goal and look you want
or play with the beam angle to get it very large may be !

or second pic with control over the way the spotlight shoots light with plane
see pic 2
hope it helps

your shadows are still diverging heavily though. Not on the box but on the door way. My goal is sunlight. The sun casts parallel shadows because its extremely far and is larger than earth. If sunlight were to try to be reproduced in a CG scene with diverging shadows it would look slightly unnatural. I’m beginning to get frustrated with the volumetric light. It finally seems I finally got the fog to be occluded by objects, but now suddenly for some reason its not casting shadows. When I fool with setting the responses I’m getting with the light are seeming utterly arbitrary.

have you tried with yafaray
might get lucky
it has more powerfull rendering!

hope it helps

increase samples for it to pass through things and have the halo occluded.

I’m beginning to get frustrated with the volumetric light.

That is because it is not really a volumetric light. I have pretty much given up on Blender lighting (AO is nice), but I still can not find an external renderer that supports volumetric light. Lux does not (funny that a light accurate renderer cannot do beams of light), Yafaray is probably my next exploration. There is a lot of heavy development going on with Mosaic and Aqsis that could pan out when it settles down.

there is only one way but not certain how to do it in blender!

set a spot light at the focus of parabola 3D and let it shine toward the parabola to create
parallele light rays from the parabola soruce

but this is indirect lighting and cannot be done in blender!

onyl yafaray might be able to do this to get your parallel rays of light ?
but i never tried that before

i’v rarely seen this sort of effect with light !

now i in blender you can change the path of light rays with a lens so may be this could help do what you want ?

hope it helps

Well thanks everyone for your responses. I’m giving up though. Ricky that sounds really complicated haha. The “sun” light type obviously casts parallel shadows in blender, but I can’t do “halo” with it. But then again it seems I can’t do halo with a spot light either so whatever :). Nothing is working for me right now. Even the “mist” functions is not working correctly. No matter what i set the values to its blasting my entire scene with a uniform fog everywhere. It only happens in the scene I want to use it in though… if I try it in a fresh new scene it works perfect. I think my scene is just getting jacked up by something. I’m going to have to composite all this stuff in.