View Full Version : Transparency reflection blow out

11-25-2010, 06:34 AM
Im rendering a product shot which has a glass cylindrical element. I need about 30% reflectivity on the glass however when I increase the transparency of the glass the surface begins to really burn out, does any body have any fixes for this please.

I have no diffuse or any other attributes selected on the glass - simply reflectivity and transparency.

Im rendering full Monte carlo using Fprime.



11-25-2010, 11:14 PM
What is it reflecting? If it is luminous polys, they can be lowered.

11-25-2010, 11:16 PM
Lowering radiosity may help as well.

11-26-2010, 07:42 PM
Sounds like whatever is behind the glass is bright. The reflection will add to whatever is behind it. If that's not it, post an image -

11-27-2010, 05:10 AM
It's a lot easier to use the dielectric material for glass surfaces

11-27-2010, 07:09 AM
Actually diffuse should be very low if not off, it still has an effect even if it's not being used much. the golden rule about 'reflection' is that is:

Reflection + Diffuse ≤ 100%

Because diffuse IS a form of reflection, so surfaces can't (normally) reflect more than 100% of the light they recieve!

It's simple to do glass properly... As below.. If you want absorption, like dielectric does, it's probably simpler to add dielectric, though quite possible to do! :) (or you could just use colour filter which works nicely too!).

Glass will always look wrong if you don't have a gradient (Fresnel) falloff, and just use a flat value.. Add reflection/refraction blur to taste.