View Full Version : Why Specular does not appears in my Radiosity scenes?

Amilton Diesel
09 September 2003, 03:56 AM
Hi everybody! that's my first post and my first question:

I know that Radiosity in Max 5 still have problems but i think is very weird that this render do not show the simple specular efect. In my scenes all the materials looks extremely difuse and the specular efect only apears when i put photometric lights close to the objects. I have trying other shaders but the result still bad.

Any help is welcome.

09 September 2003, 09:09 AM
IIRC this is a limitiation of the radiosity algorigthm itself. I don't know much about radiosity in 3ds, but if you can, add a few spotlights where necessary that affect only specular but not diffuse light.

09 September 2003, 03:52 PM
A good mix of the regular max lights and the photometrics can provide new look and better detail in your lighting solution.

Amilton Diesel
09 September 2003, 06:27 PM
Thank you all:applause: It was very usefull

09 September 2003, 09:44 PM
i would render a second pass with just to get good specularity, i could change lights positions to improve the look.
this pass doesnt use any radiosity /GI/FG, just pure black shaders and lights. then you could compose the 2 passes together and control the speculars(highlights) in the way you want.

10 October 2003, 06:50 PM
cause in real life there are no speculars and radiosity imitates real life. speculars in real life are reflections of bright light sources so you have to turn reflections on. it might help to create a sphere around your scene that only shows up in the reflections. on this sphere you shoud place a surface shader or whatever it is called in max that has a texture that all your objects will reflect.

Amilton Diesel
10 October 2003, 07:01 PM
Thanks, the standard lights with only specular already solved the problem. Radiosity ilumination and standard light together can produce good results really.

10 October 2003, 06:35 AM
Specular highlights occur when you have a small intense source of light bouncing off a surface and striking the camera. Radiosity is not a direct source of light, rather it is a very broad diffused light coming from just about any direction. Radiosity will not cause specular highlights unless it is in a very small focused area.

My description is not entirely accurate, but hopefully it gives you an idea. A flashlight will cause a specular highlight provided the surface is reflective enough, but the sky won't cause it because it is far too large and diffused.

Hope that clarifies things a bit. If you think your scene should have highlights, maybe what you're looking for is called caustics. When an intense light (like the kind that cause specular highlighting) bounces off a surface, it can strike another and cause a highlight there as well. That, in the CG world, is known as caustics. If your renderer supports that, then turn it on and you may see the results you're looking for.

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