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View Full Version : Unwanted patterning in volumetric lights shooting through transparency holes



AbstractTech3D
07-11-2012, 12:12 AM
Hello

I have a volumetric point light inside a sphere. The sphere is surfaced with an image defining areas of transparency (holes to let the light through). However, I'm getting an unwanted patterning occurring in the resulting beams of light emitting from the sphere. I would have expected to see solid beams of light. (No texture is applied to the volumetric light).

See attached.

Can anyone explain what is happening?

Thanks


Edit:
Have discovered that turning on 'jittered sampling' (volumetric light options) results in a more solid beam, but requires ridiculously high levels of antialiasing to be acceptable.

Further, have tried applying the 2d image texture nodally to the point light volumetric density and luminosity channels. Turning off the sphere gobo. Turning off jittered sampling. Strange results seen in (2nd) image attached.


If anyone has any idea how to get the result I'm after (not the patterned effect), efficiently (not with AA set to 32!) - I'd really like to hear!
Thanks

prometheus
07-16-2012, 03:41 PM
You should repost, your scenefile wasn´t saved properly with name and lws extension.

I could rename and open it, but you have named your light to volumetric dome lights, dome lights can not be volumetric, your light is a point light.

however after those confusing items, the point light doesnt not have the node editor active or setup for the volumetrixs as you have in the scene, so i cant help really.

Michael

Sensei
07-16-2012, 08:05 PM
Turn on Jitter Sampling..

Volumetric handler is receiving ray info- ray origin and ray direction and length (clip near and clip far scalars). To render volumetric light there is made something like

int quality = 100;
for( int i = 0; i < quality; i++ )
{
vector pos = ray_origin + ray_direction * clip_far * i / quality;
// check if 'pos' is in volumetric light or not..
}

so the more quality samples, the better result. But it's like in motion blur. You recall how old post-process motion blur looks like.. ?


If anyone has any idea how to get the result I'm after (not the patterned effect), efficiently (not with AA set to 32!) - I'd really like to hear!

Model light beams by hand? ;)