Cracks in render

Carrara (Integrated Plugin developed by Sighman)
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tschwenke
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Hi,

Don't know if someone has encountered this problem, but there seems to be a problem either in Carrara or the Plugin.

When there are cracks in the render (see before smoothing), I go to the Vertex modeler and enable Smoothing for the model. It's updated in the Renderer. Then, I disable smoothing (= None) and the rendering is fine without any cracks (= after smoothing). (Please note that in both screenshots, there is not smoothing applied! The model was just smoothed and disabled afterwards.)

Any ideas why this happens?
Attachments
After smoothing
After smoothing
Before smoothing
Before smoothing
http://www.thomas-schwenke.me
Houdini 20.5 || Win11 || i7 + RTX3080
protovu
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Joined: Thu Sep 11, 2014 7:30 pm

Not sure if helpful, but.......
I have had some issues regarding Octane render viewport when it pretends to update, but then does not really update. This has been with changing bitmaps within Materials.

The viewport blinks on the change, and seems to be regenerating, but does not really do so until I click the "rebuild scene" icon of the viewport.

The other suspect in my experience has been the "Open SubD Settings" tab. I tried it once and it generated some cracking.
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tschwenke
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Hi Rick,

Thanks, but it's not a SubD problem. I just found out that it's a Carrara bug. If I open a saved Carrara file, some models come in with cracks. After clicking "Smooth" and, afterwards, disabling "Smooth," the problem is gone. It's only for highly polygon models... Don't know why it happens...
Attachments
no-cracks.jpg
cracks.jpg
http://www.thomas-schwenke.me
Houdini 20.5 || Win11 || i7 + RTX3080
protovu
Licensed Customer
Posts: 476
Joined: Thu Sep 11, 2014 7:30 pm

I get this with client .step file sometimes. Once converting them from Primitives, smoothing makes them worse, sometimes requiring a rebuild. Adjusting the import settings/angles can sometimes help.
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tschwenke
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Hi Rick,

Yes, that's true. This model is also an STP file. I usually use the "Untriangulate" tool in the Vertex modeler, as smoothing Tris isn't a good idea as you say. I use now a tool Sparrowhawke3D created some time ago for me. It's a tool to create section cuts, but you can also adjust the smoothing angle. It works fine now.

Thanks for your support! And happy medical rendering :)
http://www.thomas-schwenke.me
Houdini 20.5 || Win11 || i7 + RTX3080
protovu
Licensed Customer
Posts: 476
Joined: Thu Sep 11, 2014 7:30 pm

Hi Thomas,
I have had very unsatisfactory results with the untriangulate function within Carrara.
Thanks for the Sparrowhawk tip.
Cheers!
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