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Dirt in render

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mikolaj64
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Hi, could you please advise what may be the reason of rendering imperfections like the one shown on an attached image?
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mikolaj64
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Attached image

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crystal.jpg (262.9 KB)

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mikolaj64
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OK, I see what's the problem. It's pixel samples in matra renderer. I increased it and it's fine now.
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mikolaj64
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I have increased pixel samples to 9 and the rendering is extremely slow. Moreover some of those dirts are still there. Do you know any more efficient way of dealing with it?

And one more question. Why there are white stripes across crystal? How can I remove them?
Edited by mikolaj64 - 2017年1月28日 03:22:52
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matthew_h_k
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Hi mikolaj,
Without knowing what geometry you're using, or what lighting & render settings, it's difficult to give assistance.

But, you could check the following:
1) Your normals - perhaps add a facet node at the end of your geometry network and select the ‘Post-compute Normals’ option?

2) The ‘raytracing bias’ settings on the Mantra ROP > rendering > shading > tab. If that's set too high for your scene scale, there can be artifacts in renders.

3) And as for the white lines - without knowing your scene setup, it's hard to say, but it may be normals related too.

Hope this is of some help,
Matt.
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mikolaj64
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It's just simple Platonic object with Facet and glass material. Raytracing bias is set to 0.001 and object is in the default size.

Could you please try to render a clean crystal like this?
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matthew_h_k
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Hello again,
Here's a quick render I did, and as far as I can tell, it's pretty clean.
I have attached a hip file - you'll need to replace the hdr image in the env light - see if it helps in any way.

Matt.

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Screen Shot 2017-01-29 at 12.01.34 AM.png (387.4 KB)
glas_render_test_v02.hip (346.3 KB)

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mikolaj64
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Hello Matt,

Thank you for helping me with this. The problem was rolling background I created. It is very strange that such background creates such effects. Very disappointing.

Cheers

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background.jpg (20.7 KB)

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anon_user_37409885
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mikolaj
Hello Matt,

Thank you for helping me with this. The problem was rolling background I created. It is very strange that such background creates such effects. Very disappointing.

Cheers
Just upload your file or log a bug. Being disappointed is boring.
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matthew_h_k
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No problem mikolaj, glad you sorted it out.

Matt.
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