Using subtle glossy relections to imitate BRDF

[Burnsyman9000]

Just thought I'd throw this out there, but lately I've been finding that adding subtle glossy (blurred) reflections to all materials in a scene, even masonry, asphalt, grass etc, seems to give a little extra realism to the final rendering. I guess this makes sense when you think about how materials actually reflect light (ie. think of BRDF in Maxwell), no materials are completely diffuse or completely specular but are always some combination of both, even very matte materials. Am I on the wrong track here or has anyone else played with this?

[joconnell]

Nope, you're totally right - nearly any material has some kind of specularity, it just depends on how much of a difference it makes and whether it's worth the render time.

[dimo]

Hi,

yes you are right. Chris Nichols shows this on his Gnomon exterior DVD, too. He adds a small amount of glossiness to the materials. He also explains why this is a good idea and has some good examples. After all a phong "highlight" is just a cheap fake of a glossy reflection of the light source. That's the reason why the highlight and the glossines is connected in the VRay Material.

Best Regards,

Dieter

[Clifton Santiago]

I put a bit of fresnel glossy reflection on almost every surface. I use either interpolation or store glossies in LC to compensate for increased rendertime. I learned this trick from Chris Nichol's gnomon DVD as well.

[Burnsyman9000]

Cool, thanks for the feedback, so fresnel glossies eh? I wasn't sure if it made sense to use fresnel or not on mattish materials like wood and masonry, any thoughts on this? I guess I'll experiment with both. Does anyone know if fresnel relections render slower than non-fresnel reflections. One more question: If I use the LC to store glossy rays, will I get noisy looking reflections with low LC subdivs (500 for example)?

[Clifton Santiago]

I don't think fresnel has any effect on render times. I choose to use that instead of putting a fallof map in the reflection slot. I don't know about the low LC subdivs. I assume the material subdivs would be the important thing.