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Cycles Importance Sampling


Some really interesting work is being done on Cycles by community member tuqueque. One of his results: improved image quality with 'Importance Sampling'

Josh Faulkner writes:

User MikeFarny has created a patch to Brecht's Cycles render engine to perform improved sampling for certain types of scenes that have had some very interesting results. The Blenderartists link has the history and some user tests that show massive improvements in image quality - there are generally less samples in the same amount of time compared to vanilla Cycles, but since the samples are smarter, the resultant image is clearer. Check it out!


Three of the more astonishing examples from the thread:

About the Author

Avatar image for Bart Veldhuizen
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. Work smarter, not harder. I like this idea.

    Can the region of interest be user defined? The closest comparison I can come with is the (defunct?) ability from default renderer to just render a square that the user could define...

  2. Very cool feature. I read that Mike Farny is developing bidirectional path tracing. I cant wait to see it on cycles to improve interiors that cycles cant handle. Nice job.

  3. Who cares if samples are slower as long as they decrease and give better results
    Speed can be a next step to more blender charm

  4. Tuqueque should be given the right to edit/complete this article as he is the one behind the project (he was preparing a blendernation post for his baby): he would give proper credit to Mike Farny....

  5. At the moment I can't use Cycles as an animation renderer... but this development could change all that!  Fantastic work. Now we 'just' need OpenCL support so the other 50% of users can get a nice GPU speed up too.

  6. Ehm this examples are not from tuqueqe;
    these are from me (Tungee)! ;)
    No problem that you use it here on Blendernation;
    but dont forget my name on this thread.

  7. Sorry if some of the facts are fuddled, guys and gals.  I was really excited to see the improvements that I wanted the whole Blender world to know!  Just for clarification, Mike posted this in the BA thread:

    "It should probably be edited to note that the improvements are related to background/environment [lighting] only, so we don't disappoint people when they try it with their mesh lights and see no difference."

    Keep up the good work, everyone!  Blender just keeps getting better and better!

  8. Haha, exactly, as tungee said, I'm tuqueque and the only thing I did was start the Blenderartists thread. All the credit should go to Mike and this awesome community :).

  9. Off topic, but I found something about speed, recently I was using 3D Slicer to render the skull of a dinosaur and it run ok in 3D Slicer, but once I tried to export the mesh to Blender, I had to hide most of the mesh to be useful.

    Then I looked why and 3D Slicer uses VTK(Visualization Toolkit) a medical open source project that implements a lot of tools for imaging that are used for scientific and medical purposes and those implementations are fast, blazing fast.

    Those could have an impact on speeds for rendering and realtime applications.

  10. Havent tried the IS yet, but Blender 2.61.3 u need to go to: "User Preferences > System" to chage from CPU to GPU, u cant change it from render panel anymore

    • Got it, thanks. Updated my drivers to support at least OPenCL 1.1, put my area lights on an unused layer, turned up my background lighting, changed it from CPU to OpenCL in the Preferences->System Tab, and voila, about 4 to 5x faster for about the same results. Nice.

        • Yes, sort of. I set the Preferences->System to OpenCL and under the Render options, I change it from Supported to Experimental. This creates a button just below for the GPU. Then I make sure all my area lights are either off or on an unused layer. Then I click on the Environment Icon in the Properties Menu and unclick Sample as Lamp. It runs a lot faster than the usual CPU option (at least on my GTX 560 ti), but unfortunately, doesn't show the image textures when using OpenCL (yet) Hopefully it will all work in the future, because it's FAST.

  11. i was testing it, but there was no difference between IS and the latest official build of Blender... Does it only work, if i'm using GPU?

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