Clear plastics don't let diffuse colors through...sometimes

[Peter H]

I have a question about clear plastic materials. The situation is when a clear plastic part covers other parts. With global illumination and caustics turned off, only specular colors (not diffuse) show through the transparent plastic. If I use glass instead of plastic, I don't have this problem.

Maybe most importantly, this only occurs if the clear plastic part 'caps' the other part, so it happens in image 2 but not image 3.

I'll attach images.

Image 1: model with both clear parts set to 'glass refractive white'
Image 2: model with both clear parts set to 'clear shiny plastic white'
Image 3: same as 2, but with the cap turned off.

I see this in both ks6 & 7.

[Esben Oxholm]

Hi!

I think it has to do with the number of ray bounces in the lighting settings tab.

Take a look at this video at 10.00. Might help:
https://youtu.be/txUNf71D2Ic?t=10m1s


Cheers,

[Peter H]

Thanks, but I have tried that. In the images I attached, I set ray bounces to 26 (I don't see any change above 2, but I set it to 26 just to see.)

[Peter H]

I'm trying to attach a .bip or .ksp, but neither will upload, despite being less than 50000kb.

[Peter H]

Here is a screen capture of my lighting page. (I wouldn't actually render with these settings - I just turned them up to crazy high numbers to see if it made a difference with this problem.)

[Robb63]

Did you try checking the "Global Illumination" checkbox in your "lighting" tab?

[Peter H]

Yes, I know that I can get a good image by turning on either caustics or global illumination, but I'm trying to report a bug that happens when those options are not turned on.

And, practically, I was recently asked to render something using someone else's ksp but with my geometry so that all of our products would look similar in terms of lighting, etc, and mine were the only ones that were affected by this bug. Everyone else was not about to re-render with those work-arounds, and so that was an issue for me.

[Robb63]

I believe that you have always had to have Global Illumination turned on to make "Transparent Plastics" work correctly? I don't know that it's a bug per se.

[Peter H]

Why should plastics require that setting, but not glass? And why does it work if the clear plastic doesn't enclose the other parts? Maybe it's only a bug in my head - that's always a possibility.

[Will Gibbons]

How is your geometry modeled? Solid, or surface? Is it watertight?

[Peter H]

Solids, watertight from Rhino. I sent a file to Luxion last week via wetransfer (can't attach geometry to this forum for some reason.)

[Peter H]

I'll at least try to attach a video capture here. Maybe that will help? In the video, you can see that when the clear part no longer completely encloses an area, the diffuse color shows through.

[Peter H]

These images show the progression of moving this plastic cap up. If it were glass, it would show the green through always. It starts out less than 0.01" above the green surface, and then these images show it moving up (1.1 the cap is moved up 0.1, 1.2 it's moved up 0.2, etc.)

[Will Gibbons]

I suspect it's the material you're using for the plastic. If you send me the file, I can take a look. Troubleshooting via screenshots can take quite some time. Try using glass(solid) or better yet, Cloudy Plastic.

[Peter H]

How do I send you a file?