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Removing Blender Cycles Artifacts In After Effects


Frederik Steinmetz writes:

In this Quicktip you’ll learn how to quickly and effectively remove black pixel artifacts that are often left behind by Blender’s real time Cycles render engine. Frederick will show us a quick and simple technique to clean these up using Adobe After Effects. This useful solution works on both still renders and animations as well.

Removing Blender Cycles Artifacts In After Effects

About the Author

Bart Veldhuizen

I have a LONG history with Blender - I wrote some of the earliest Blender tutorials, worked for Not a Number and helped run the crowdfunding campaign that open sourced Blender (the first one on the internet!). I founded BlenderNation in 2006 and have been editing it every single day since then ;-) I also run the Blender Artists forum and I'm Head of Community at Sketchfab.


  1. I need to fix black dots in blender cycles but cannot reproduce it on my computer. Please share some simple .blend file with short instruction how to get them. I am sure bug is trivial, probably big negative float point number as color or even NaN.

  2. I am having troubles with Cycles.

    I have a 20000 poly object with a lot of modifiers (bevel, armature, subdiv).

    Cycles crashes each time I try to render with it.

    Any tips from Cycles users?

  3. Joe: Cycles still in very early stage, and it is more "fast-preview" oriented then "final production render", extra filters not used for speed reason. There are too many big features missed (full scene motion blur, volumetric render if you ask me ). Implementing object motion blur can lead to almost full rewriting from scratch, at least very core of path tracer - BVH acceleration structures.

    aws357: Need more info, OS, CPU/GPU, memory size, etc. Try CPU only render first, if it crash again try use GDB/ other debugger.

  4. I think cycles was written with motion blur in mind, you can't have a renderer without it, there are some notes about implementing it on the wiki. But it will most certainly slow it down a lot, that's why I would have hoped they'd gone more toward renderman. It will probably still be great, but maybe most useful for stills. We'll see.

  5. Not really, camera only MB can be used (it is trivial, see cycles/intern/cycles/kernel/kernel_camera.h:122, only need to calculate camera move vector from next frame slice from Blender core and uncomment 1 line). Full motion blur is very hard to implement, proof - too few ray tracers have done it. Direct naive 4D BSP for example can easy eat 3X-5X memory and very long BVH build time compared to current Cycles. We need some modern complex algorithms, but they tend to be very complex and have lot of heuristics (read: lot of bugs, too few ppl can solve them, etc).

  6. The lack of motion blur doesn't hurt that much because you can do several renders of a time period and blend them together by hand or write a small python code.

    What I got into in Cycles is that I wanted to make a very quick render of an animation, I made a python script which rendered every frame into different images, then I made in the compositor a node setup which blended together the rendered image on the disk and the newly rendered image of a frame. So every time I ran the rendering script I expected the renders to get cleaner and cleaner. This would work as an incremental quick preview for animations. But here is the problem: The random seed for cycles renderer seems to be the same for every render, so no matter how many times I render the frames and blend the results together, I always get the same results. It would be good if the random seed could be modified or would modify automatically.

    And how about hybrid CPU/GPU rendering?

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