Unrealstic reflections (due to phong tag) when filleting added to a cube. What to do?
Posted: 06 October 2021 12:25 AM   [ Ignore ]  
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Joined  2021-09-03

Hi all, I’m fairly new to C4D and I’m confused about what happens to reflections when I enable the fillet option on a basic cube. The cube is still mostly flat so it should be mostly reflecting like a mirror. Instead it gets very unrealistic as you can see in the screenshot provided. I know it’s the phong tag doing this, but given that this is all about pathtracing, how can this result be so wildy wrong with such a simple object? Any help understanding what to do about this would be greatly appreciated! See attached image for example. The result here is rendered in Octane but the issue is exactly the same even in the C4D renderer.

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Posted: 06 October 2021 01:38 PM   [ Ignore ]   [ # 1 ]  
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Hi rob,

This is based on the Phong calculation (simulation).

Please have a look here:
https://www.amazon.com/clouddrive/share/LVgWjHaW31tBN9wrORLtYW3ntL4v3TFIAHBZYY6Y0Dh
Move the time slider, as I have animated the Phong Angle (the icon on the right side of the object—in the Object Manager)

More about that:
https://help.maxon.net/c4d/r25/en-us/Default.htm#html/TPHONG.html

In short, each polygon has an orientation, typically expressed with something that looks like a nail in the middle of a “board”. Now think about the neighbor polygon also has a vertical nail on its surface. The angle between the two is used to calculate the smoothness of the surface. The larger the angle between the two, the rounder it might look, if not limited by the Phong-tag.

Cheers

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004

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Posted: 06 October 2021 02:14 PM   [ Ignore ]   [ # 2 ]  
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Thank you so much Dr. Sassi! I truly appreciate your response. It’s all making a lot more sense now.

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Posted: 07 October 2021 08:35 AM   [ Ignore ]   [ # 3 ]  
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Thanks a lot, rob!

Let me know if there is anything else. I’m happy to look into it.

All the best

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004

Photography For C4D Artists: 200 Free Tutorials. Texture, Panorama, HDRI, Camera Projection, etc.
https://www.youtube.com/user/DrSassiLA/playlists

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