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View Full Version : Volumetric light settings - I'm lost!



juzliqan
03-30-2004, 10:11 AM
I hope I'm not going over frequent ground - I have tried searching for older posts but found no direct answer to this.

I am using volumetric lights for the first time (well there's a first time for everythign I guess!).

My scene is simple - I want some text to cast a volumetric shadow in a spotlight beam, with the beam visible.

So I use a volumetric light. The text I model by putting an image from Photoshop (of the text) on a rectangular object, and then make the transparency of the object 100% except where the text is.

This all renders fine and dandy with no volumetric light. But turn on volumetric lights and the whole rectangle suddenly becomes visible. I have raytrace shadows and refraction turned on.

I guess there's something I am missing here, but can't work out what?

Regards,

Julian

Mylenium
03-30-2004, 10:23 AM
Well, that's absolutely normal. You should check your surface settings - the map needs not only to go into the transparancy channel but also in the diffuse, specular and glossiness channels as well (also add them to the other channels such as luminosity if need be). The thing is, your object is not "invisible" in the transparent parts. The renderer will still use rays to evaluate its surface properties. In turn this will affect the volumetrics since it changes the sampling where your volumes intersect with polygons. Adding your textures to the other channels will remedy this to a large extent. However, a better solution would be using modeled type (unless of course you need Photoshop's layer efects applied to your letters).

Mylenium

juzliqan
03-30-2004, 01:32 PM
Thanks - at least I know now I'm not being totally stupid!

Fortunately I want flat text with no complex Photoshop effects, so I shall import the text from Illustrator instead.

Regards,

Julian

juzliqan
03-30-2004, 02:24 PM
Great - that's all working fine now. Time for the next question:)

When I render the scene the letters appear with a speckled pattern over them. Now I have a faint memory of something like this once before, but cannot for the life of me recall the details.

Helpful suggestions gratefully received!

Julian