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Depth Megre


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#1 maxic

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Posted 03 December 2013 - 08:21 AM

Greetings. Here is a question about depth merging and aliasing.
I merge a simple square and some spheres using depth merging.
I know that in Fusion all passes are outputed without AA, but is there a way to overcome this? Like, every time when we use Depth Merging, Object ID, Material ID we get terrible aliasing on edges.

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#2 Dunn

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Posted 03 December 2013 - 08:46 AM

Not sure if this would work out for you, but Eric once did a video about Normals Shader AA stuff :



#3 lewin

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Posted 03 December 2013 - 08:55 AM

You can refer to this blog-----http://blog.sina.com...460101j0n1.html

#4 Tilt

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Posted 03 December 2013 - 09:32 AM

Antialiasing and z depth are different problems. Yes, coverage can help you get better mattes from an object id pass. But for z, there is no such trick.
A z channel has only one depth value per pixel, which is either in front or behind the background's z value.
The only way I know of that can help you is rendering out everything at twice the resolution. Then merge, then scale down to the original size. This way you will basically have 4 depth values per pixel and you can get nicer antialiasing.

#5 mattdleonard

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Posted 03 December 2013 - 11:47 AM

This issue your seeing is the very reason Deep Compositing was invented by the guys at Weta Digital and Animal Logic.

As Tilt says in normal situations you only have one sample of data for each pixel, but with Deep data you have multiple, maybe 20 or 30. With this much information compositing based on depth works much better as the anti-aliasing is preserved.

I've been running some test recently and I'm getting good results out of RenderMan, Arnold and V-Ray.

Hope this helps, its a really interesting subject. Unfortunately the file size of Deep data is pretty big so many studios are not using it.

Best regards,

Matt

#6 iLuso

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Posted 04 December 2013 - 03:14 AM

I think this problem can be solved by using position pass for displase geametry and cut it with matte.
It's not perfect, but much better than Depth Merge.




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