KeyShot Forum

Archive => Support Archive => Topic started by: Peter H on November 20, 2017, 09:08:36 AM

Title: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on November 20, 2017, 09:08:36 AM
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.
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Esben Oxholm on November 20, 2017, 09:19:07 AM
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,
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on November 20, 2017, 09:24:27 AM
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.)
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on November 20, 2017, 09:28:14 AM
I'm trying to attach a .bip or .ksp, but neither will upload, despite being less than 50000kb.
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on November 20, 2017, 09:37:42 AM
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.)
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Robb63 on November 20, 2017, 09:56:09 AM
Did you try checking the "Global Illumination" checkbox in your "lighting" tab?
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on November 20, 2017, 10:49:44 AM
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.
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Robb63 on November 20, 2017, 11:17:30 AM
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.
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on November 20, 2017, 11:42:12 AM
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.
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Will Gibbons on November 27, 2017, 09:06:21 AM
How is your geometry modeled? Solid, or surface? Is it watertight?
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on November 27, 2017, 10:16:31 AM
Solids, watertight from Rhino. I sent a file to Luxion last week via wetransfer (can't attach geometry to this forum for some reason.)
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on November 29, 2017, 09:25:17 AM
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.
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on November 29, 2017, 09:42:36 AM
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.)
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Will Gibbons on November 30, 2017, 08:21:18 AM
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.
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on November 30, 2017, 08:44:02 AM
How do I send you a file?
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Speedster on November 30, 2017, 12:56:38 PM
These may help. 

1)   Be sure the entire model is lifted just a tiny bit above the ground plane.  This should kill the black shadow.

2)  Make sure there is no contact between the inner components and the jar.  Use scaling on the jar, about 1.002 or so.

3)  Be sure to uncheck "Global Illumination Cache" on the Render > Options tab, way at the bottom.  For some reason this plays havoc with clear and cloudy plastic.

Bill G
Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on December 05, 2017, 05:41:25 AM
Thanks for taking the time to reply.

1) I'm not having a problem related to the black shadow at the bottom (though I appreciate the tip.)
2) There is no contact - I always build with tolerances for paint and assembly, so that is not an issue.
3) Unchecking or checking "Global Illumination Cache" doesn't change the problem.

Title: Re: Clear plastics don't let diffuse colors through...sometimes
Post by: Peter H on December 05, 2017, 05:54:35 AM
Will, I've sent you some files via WeTransfer.