Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] Bug Reporting => [Max] Resolved Bugs => Topic started by: ilinin on 2020-02-05, 19:24:19

Title: Incorrect Shadow Shading
Post by: ilinin on 2020-02-05, 19:24:19
Hi
I couldn'd find this reports on forum or anywere else.
It looks like Corona incorrectly rendering smoothing groups, when there is transition from round surface to flat.
To compare I've attached Vray render and scenes.

Does anyone knows how to fix it?
Title: Re: Incorrect Shadow Shading
Post by: GeorgeK on 2020-02-07, 15:54:53
Hi ilinin

At first look there is something wrong with your mesh,did you import it by any chance? (see scrnshot_12)

In the next example corona vs vray left hook has smgroup 1 for the straight part and smgroup 2 for the curvature. Not big differences here.

But it is strange that your model behaves differently in Corona, we will take a deeper look at this.

Lastly as a fast solution for your issue, apply turbosmooth on your mesh.
Title: Re: Incorrect Shadow Shading
Post by: Frood on 2020-02-07, 17:34:52
we will take a deeper look at this.

Shadow terminator. Try shift 0.05 for example.


Good Luck



Title: Re: Incorrect Shadow Shading
Post by: ilinin on 2020-02-08, 17:20:56
This mesh was done in max only, but the problem looks  very similar to CAD meshes.


Shadow terminator. Try shift 0.05 for example.

Shadow Terminator solved the problem. Thanks Frood!
Title: Re: Incorrect Shadow Shading
Post by: romullus on 2020-02-08, 17:26:59
Could you show wireframe of the mesh? I never saw shadow terminator issue on similar meshes, would be interesting to know what topology i should avoid.
Title: Re: Incorrect Shadow Shading
Post by: GeorgeK on 2020-02-09, 08:20:39
we will take a deeper look at this.

Shadow terminator. Try shift 0.05 for example.

Nice one thanks!

Quote
Could you show wireframe of the mesh? I never saw shadow terminator issue on similar meshes, would be interesting to know what topology i should avoid.

Attaching a screenshot.
Title: Re: Incorrect Shadow Shading
Post by: romullus on 2020-02-09, 10:36:48
Thank you George! I don't see nothing wrong with topology. Will have to keep shadow terminator in mind if i'll see strange shading in the future.
Title: Re: Incorrect Shadow Shading
Post by: GeorgeK on 2020-02-10, 09:43:14
Thank you George! I don't see nothing wrong with topology. Will have to keep shadow terminator in mind if i'll see strange shading in the future.

Apparently this seems to be something with the rotated edge topology and the curvature that it didn't like. I did a quick edge flow and straightening and the issue disappeared like exactly with the tubes I posted on the initial screenshot.

Reported.

(internal id=459035582)
Title: Re: Incorrect Shadow Shading
Post by: Frood on 2020-02-10, 12:53:45
there is something with the rotated edge topology and the curvature that it didn't like

Depending on what you've exactly found or fixed: it may be a suitable fodder for Corona Scene Check if you see any chance that issues like this one could be detected generally :]


Good Luck