Author Topic: Solid glass sphere  (Read 1103 times)

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Offline martinwahlberg

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Solid glass sphere
« on: April 07, 2018, 03:20:21 pm »
Hey guys, I have run into some issues while creating glass spheres. I have no idea if this is a modeling, material och settings issue. Or maybe it is even expected.

I used the solid glass material and I see some issues along the edges of the spheres. If I switch to basic glass material the issue goes away completely. However I would like realistic refractions so I presume solid glass is appropriate. The spheres have a thickness but I modeled them a little differently geometry wise to see if it did anything. And of course one of them is a true sphere and the other is more like a light bulb dome thing. They both are solid pieces of geometry and have a thickness.
Here is the geometry and the render with weird reflection- or refraction issues.

Any input is much appreciated.

« Last Edit: April 07, 2018, 03:22:01 pm by martinwahlberg »

Offline martinwahlberg

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Re: Solid glass sphere
« Reply #1 on: April 08, 2018, 01:04:32 pm »
Did some more testing today, increased the detail/tesselation with minor improvement.

Offline MWo

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Re: Solid glass sphere
« Reply #2 on: April 08, 2018, 09:50:33 pm »
Nice test. Did you tried simple glass with refractive option checked? Or, have compared this with dielectric material?

Wich version of KeyShot do you use?

Cheers
Marco

Offline martinwahlberg

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Re: Solid glass sphere
« Reply #3 on: April 08, 2018, 11:55:50 pm »
Thanks for the input Marco. That simple glass with refractive option checked never crossed my mind. Although I don't really understand what the difference between that and solid glass is it seems to work pretty well. I use Keyshot 7 by the way, or 7.3.37. Tried dielectric material as well and tried reversing the faces of the interior faces but had no real luck. From what I can tell your tip on using simple glass with refraction seems to work best. It would be interesting if someone could explain why the refractions produces that facetted result with solid glass.
Anyway Marco, big thanks!

Offline DriesV

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Re: Solid glass sphere
« Reply #4 on: April 09, 2018, 02:53:23 am »
This looks like it could be a surface normals issue.
Can you share the model or scene?

Dries

Offline martinwahlberg

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Re: Solid glass sphere
« Reply #5 on: April 09, 2018, 04:53:52 am »
Well Dries, you are on to something here. Are you "supposed" to create spheres with normals facing the same direction for both surfaces? It looks better and the "facetting" is a lot lessened.
My model section is showing backside faces in pink.
If you look closely at my latest render, with the model placed corresponding to the image of raw geometry with the section plane, I think that there is still a hint of the "problem" still visible while using solid glass. I'm not sure if it is a modeling or tasselation issue. What do you think Dries?
The two spheres to the left have the exact same geometry besides the inner surface normals facing the opposite direction.

Offline martinwahlberg

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Re: Solid glass sphere
« Reply #6 on: April 09, 2018, 04:55:15 am »
Here is the scene.