I have some pixi dust that flys next to a wall. I want the glow from the dust to illuminate the wall. So i guess i need the particles to emit light? How should I go about doing that?

-jon

Hey,

Actually they showed exactly that at the Houdini Meeting. It was awesome. It has to do with a new feature in Houdini and I can not remember if it was scatter or something else. Maybe someone with a better memory can fill in the details. But they illuminated a turtle that way and it did look like pixie dust. Yes it was particles.

Cheers,
Nate Nesler

Hmmmm, i don't remember the turtle from the meeting. You referring to the SSS example of the Budha?

I have been thinking over my question a bit more…..i think it basically comes down to any object that is emitting light. Doesn't have to be specifically for particles, but rather for an object to emit light, as it will be instanced over the particles eventually. It sounds like a shader problem. For example in Lightwave, you can have an object use its luminance channel to emit light when it is coupled with radiosity. I am sure there is something similar to this in Houdini?

-jon

You are looking for the ability to do light instancing. This existed in Houdini6 and is very useful.

Any surface can emit light but that requires the global illumination features in Houdini have to be used. There are tutorials and videos describing both of these features here:
http://sidefx.vislab.usyd.edu.au/houdini_video/by_topic/rendering/index.html
[sidefx.vislab.usyd.edu.au]
Look for Light instancing video and Global Illumination - Irradiance video.

In Houdini7 you can use point clouds to render particles as lights even more efficiently than doing the standard light instancing techniques and is a variant of the light instancing technique described above.

Hey,

Yeah thats it thanks jeff I could not remember. No this was a turtle with the Point Cloud I am not talking about the SSS with the Budha model although that was very cool and we are looking at implementing it along with Houdini escape in Visualization for Architecture once some more contracts come in.

Cheers,
Nate Nesler

MatrixNAN
Hey,

Yeah thats it thanks jeff I could not remember. No this was a turtle with the Point Cloud I am not talking about the SSS with the Budha model although that was very cool and we are looking at implementing it along with Houdini escape in Visualization for Architecture once some more contracts come in.

Cheers,
Nate Nesler

You guys shuld visit od [odforce.net]
There you will find a submission by Mark Elendt in the “Rendering” forum under the topic “PCPack : subsurface, ambient occlusion, etc”. This is a bundle of point-cloud related shaders, which includes an SSS shader (“sfsss.vfl”), a “point cloud as light sources” example (“pcplastic.vfl” – which I imagine is what they used for this turtle demo you talk about), and an example of using point clouds for ambient occlusion (“fastgi.vfl”).
You can also check out an alternative SSS implementation using point clouds in the “Scripting” forum under the topic “Subsurface Scattering Using Point Clouds” (why is that under “Scripting”?…. my fault…don't ask)

Cheers!

just letting everyone know that I just moved Mario's topic “Subsurface Scattering Using Point Clouds” to the rendering forum of od so that the topics would be all together…

Aahh; thanks Arctor!