PDA

View Full Version : Volumetric lighting issues


wardy150
08-12-2010, 08:19 AM
I've recently been learning about volumetric lighting and using the parti_volume node. I can get it to work fine but I'm looking to find a way of making the rest of the area outside of the light beam to not be affected by it.

Here is a render of my scene, using a spot light with physical light attached and emitting photons for the light beam effect. There is also an area light lighting up the interior. The whole scene is surrounded by a poly cube with a transmat material which the PM node is connected to. GI on.

Now the light beam looks fine, but the rest of the scene is foggy. The area light is having next to no influence.
http://img194.imageshack.us/img194/5206/withouts.jpg

Here's what it looks like with the spot light turned off and the parti_colume cube turned off. This is what I would like the lighting to look like.
http://img830.imageshack.us/img830/687/with.jpg

How can I prevent the volumetric lighting from spreading all this fog into the scene and changing the lighting in the rest of the interior? (Making the volume lighting cube smaller to just encompass the area of the light beam looks odd).

Cheers

InfernalDarkness
08-12-2010, 06:10 PM
Do you mean like this?

http://img20.imageshack.us/img20/9865/screenen.jpg

Screen.

Or like this?

http://img43.imageshack.us/img43/2782/multiplyi.jpg

Multiply.

Hope this helps.

wardy150
08-13-2010, 12:31 AM
Thanks Infernal.

I was hoping to be able to achieve something like the multiplied image but within Maya itself, so as to not lose sharpness by comping the foggy/blurry image over the sharp one. Is there anything that I can possibly do to remove the fogginess or is it just something that is unavoidable with this type of lighting?

http://img834.imageshack.us/img834/6675/strangemuseum2.jpg

InfernalDarkness
08-13-2010, 02:00 AM
I think doing both renders then comping them in post is the way to go, honestly. You'll have full control over each then, and can even erase parts or sections (or create some kind of alpha inside Maya to help) of the volume render...

But short of that, perhaps a fog Light would work better for you? Or maybe even making some kind of different shape for your parti_volume's boundary geometry?

Alternatively, you could toss some "fake" or ambient lights into your volume scene, and set them to not react with the parti_volume. Perhaps some wide-angle spotlights with soft falloff or something in those areas you need more clarity?

wardy150
08-13-2010, 04:19 AM
Thanks again. Had a play around with a fog light and was able to get a similar result with better sharpness/exposure for the rest of the scene but unfortunately the light beam doesn't look nearly as good.
http://img192.imageshack.us/img192/4495/foglight.jpg

Alternatively, you could toss some "fake" or ambient lights into your volume scene, and set them to not react with the parti_volume.
How would I go about setting the light to not be reacted by the parti_volume?

Cheers

CGTalk Moderation
08-13-2010, 04:19 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.