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pbr SSS artifact

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pbr SSS artifact

Unread postby chulho@email.4thparty.co.kr » Wed Jan 09, 2019 11:41 am

Hi,

When maya`s translate is very large, SSS render artifact.

How can I fix it?

Clarisse is 3.6 sp7.

Best regards,
sangjin.
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sss.png
chulho@email.4thparty.co.kr
 
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Re: pbr SSS artifact

Unread postby mdkai » Wed Jan 09, 2019 2:18 pm

Hi
make sure you freeze all transformation levels, always avoid to export data that has extreme values for translate, or even worse "scale".
Most transmissive parameters like SSS are highly depending on proper world scale and position and any offset will be inherited inside the shader.

I usually freeze, clear history and output them in worldspace using the proper abc flag.
Also make sure the export/ import matches the units (usually metric cm)

Cheers
Kai
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Re: pbr SSS artifact

Unread postby chulho@email.4thparty.co.kr » Thu Jan 10, 2019 1:50 am

Thank you for reply.

I freeze translate, but it is error.

"Error: line 0: Freeze Transform was not applied because body.translateY has incoming connection."

I used cm and worldspace abc flag. Also object has rigging for animation.

Best regards,
sangjin.
chulho@email.4thparty.co.kr
 
Posts: 2
Joined: Fri Aug 24, 2018 8:55 am

Re: pbr SSS artifact

Unread postby mdkai » Thu Jan 10, 2019 9:43 am

Hey Sangjin,
this means the translation is possibly recieving key frames or any other input, which would clash with the freeze command.

Basically when you output the alembic cache geo , how far away from the origin is it when loading in clarisse ? Values of 1000000cm or 10km are still okay for clarisse in terms of distance.

But I guess there is also a scale value offset inside the setup. Can you use the tape to measure the actual size ?

Most important thing when exporting camera and geo is to always keep the scale at 1 ..pathtracer can react very odd with aovs if scale is unormalized. However I found clarisse to more robust to dealing with this misbehaviour than Arnold for example...

Remember that a scaled hierarchy usually also transfers scale into a positional offset if the "inherit transform" is on (which is default for pretty much every application like 3dsmax,Maya Houdini or Modo.

And since SSS is a very scale "sensitive" parameter you must make sure it is always 1 in every part of a hierarchy as well as the mesh itself.

Cheers
Kai
mdkai
 
Posts: 260
Joined: Tue Oct 07, 2014 7:24 pm


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