Specular Reflection/ MR FG image lit scene

[jeremybirn]

Specular highlights are only a fake, blurred reflection of a light source. If your image is your lightsource, that's what you should reflect (or a modified version of it.) If the reflections are too sharp, then reflect a blurred version of the map, or use DGS for a soft raytraced reflection (slower but gives soft occlusion of the refleciton too...) If you want to cheat in darker areas and higher contrast around the highlights, then adjust the levels in the image that's refected. In real life, the only "specular highlights" you get on a surface are where it reflects something bright.

-j

[RichSuchy]

Originally posted by jeremybirn
Specular highlights are only a fake, blurred reflection of a light source. If your image is your lightsource, that's what you should reflect (or a modified version of it.) If the reflections are too sharp, then reflect a blurred version of the map, or use DGS for a soft raytraced reflection (slower but gives soft occlusion of the refleciton too...) If you want to cheat in darker areas and higher contrast around the highlights, then adjust the levels in the image that's refected. In real life, the only "specular highlights" you get on a surface are where it reflects something bright.

-j

I already blurred the image, so I guess my image needs a higher bandwidth. Perhapse I can use a ramp to determine what gets reflected, Ill have to think on that.

But your idea of taking reflected image and processing it for the reflection is a good one. I really wanted an all around solution for any scene I happen to put the character in, but I guess I'll have to use whatever cheat I can figure out. Its prtetty work intensive to derive a reflection map for every scene to handle specular highlights.

I wonder if it would work better with sub-pixel displacement than a bump map.


Im beginning to wonder if I am better off lighting a scene as I once did and then using a low level of FG to enhanse the realness.
I guess I'll have to do some more testing.

[Tigerdog]

Hi, I also am having VERY simular problems. I can get a resonable specular reflect using a blurred verson of the light source in the enviroment slot and uping the reflection of the object a tad.

My problem is when i have other objects in my scene because they are reflected unblurred but i cant just exclude there reflections either because they need to be reflected other wise i will get specular highlights through walls and other objects which should be bloking these highlights.

[Andrew W]

In the excellent "Production Ready Global Illumination" paper at Siggraph 2001 ILM described a piece of RenderMan code that they used to boost the dynamic range of regular 8-bit photos of cgrome balls. I think you may find it advantageous to do something similar. I reckon a ramp with some greater than 1 values for the big hits should work.

I would also suggest rendering a seperate reflection pass (ie chrome pass) and add the reflections in the composite. That way you get much more control of the gamma, tint etc of the reflections.

A

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