Black pixels in render when using Cycles material

Question

I already tried adding more subivisions, tweaked the light bouncing parameters, etc, but I cannot get rid of the black pixels when using Cycles material copied from a YouTube video.

Here is the source if someone wants to check it out:

https://dl.dropboxusercontent.com/u/1541106/spots.blend

Thanks!

Those can be partially noise caused by render settings, partially black light bouncing from the background. — Mr Zak, Jul 20 '16 at 19:46
@cegaton Nvidia GTS250 under Archlinuxx64, with 340xx drivers. — Gabriel, Jul 20 '16 at 20:32
@MrZak i had the world background set to black, set it to white and the same thing happens. edit:i even "disabled" it. — Gabriel, Jul 20 '16 at 20:33
Actually your file crashed Blender for me because of OpenSL usage.. However anyway I don't have any of those black pixels rendering on CPU. Rendering on GPU could be one which causing the problem (although I can't test that). — Mr Zak, Jul 20 '16 at 20:52
GPU rendering here and no black noise to speak of, you just have to let your render calculate more samples over time, although you do have a very small frequency noise texture affecting your material normal. That is bound to cause some noise, especially having the Factor black and white socket affecting normals which may cause issues. Subdivisions won't help here, only make it worse — Duarte Farrajota Ramos, Jul 20 '16 at 22:02

score 0 · Answer 1 · answered Jul 20 '16 at 19:41

0

I am not getting those spots when I render the scene. Perhaps try rendering with the CPU instead of the GPU.

I rendered with the CPU. My results:

answered Jul 20 '16 at 19:41

HoltH

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Actually, i'm struggling with getting CUDA to work on my system and i'm currently working with CPU. – Gabriel Jul 20 '16 at 20:07
Your card is quite old, do not bother with CUDA. Support for cuda v1 was dropped a in blender a while ago. – Jul 21 '16 at 01:12
@cegaton perhaps you are refering to CUDA v7 which dropped v1. CUDA, because i found nothing related in Blender. 6.5 should work fine with my card. – Gabriel Jul 21 '16 at 02:45
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I meant CUDA compute capability. Quote Form the blender manual: We support graphics cards starting from GTX 4xx (computing capability 2.0). List of CUDA cards with shader model The mentioned card has a 1.1 cuda capability see: https://en.wikipedia.org/wiki/CUDA – Jul 21 '16 at 06:21
@cegaton oh, i see, bummer. Thanks for the hint! – Gabriel Jul 21 '16 at 16:48

score -2 · Answer 2 · answered Aug 20 '16 at 15:11

Have you happened to read ? https://www.blenderguru.com/articles/7-ways-get-rid-fireflies/

When I use glossy shaders, I get a lot noise like stuff, and stuff from this article has helped me a lot.

Based on the screen caps, because the file actually crashed for me, I noticed your samples look kinda low. If your willing to let your computer crunch for awhile, up the samples and picture should look better.

And I never rely on the viewport rendering, that gives you a rough idea how it all come out, and lets you change things in real time because it isn't going ham on making a purty picture. But if your going to submit this to something, you gotta see the finished polished product.

Hope this helps.

Black pixels in render when using Cycles material

2 Answers2