Product vs Interior mode changes refraction

[zachraven]

Hi everyone,
I am using a dielectric material that is "back painted" (think of a glass whiteboard, white paint on the back surface of the glass). Since its dielectric and I have physical lights, im using caustics so the light penetrates the glass. My issue is product mode renders correctly, but is SLOW. (1.1 frames/sec). Interior mode is WAY faster (24FPS), but interior mode seems to change the refraction of my glass. See the screenshots I've attached. Unfortunately I can't show the whole image due to NDA. Any ideas on what I can do to use interior mode since its massively faster?

[mattjgerard]

no answer, but since I learned about diaelectrics and indoor modes, my rendering is not the bottleneck in my production process anymore. There are some things to watch out for (like this, which I haven't run into yet) but there are usually workarounds, i just don't know about this one!

[Will Gibbons]

Hi everyone,
I am using a dielectric material that is "back painted" (think of a glass whiteboard, white paint on the back surface of the glass). Since its dielectric and I have physical lights, im using caustics so the light penetrates the glass. My issue is product mode renders correctly, but is SLOW. (1.1 frames/sec). Interior mode is WAY faster (24FPS), but interior mode seems to change the refraction of my glass. See the screenshots I've attached. Unfortunately I can't show the whole image due to NDA. Any ideas on what I can do to use interior mode since its massively faster?

Just a shot in the dark here, but I'd use the plastic and glass materials instead of advanced and dielectric (maybe they're less common materials that are causing the discrepancy).

I'd apply the image as a label to the back of the glass (planar mapping) and set the depth to something like .2mm (just so it only shows on the back of the glass). See if caustics are 100% necessary, they may or may not be. Maybe interior mode will work. If not, go product mode with denoising. Or try GPU mode. And that dispersion you have in there is likely not necessary and that slows things down a ton.

[zachraven]

Thanks will! I'll give your suggestions a try. Interesting to hear about dispersion slowing things down, I'll remove that also since it doesn't seem to make a visual difference.