Particle instancing to save Cycles memory

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When rendering a scene to Blender Cycles with lots of vegetation, we noticed how it took so long to load the geometry into the BVH. We also noticed a string of text saying “0 duplicates”. After googling a bit, we found this post in BlenderArtists, advising strongly to use particles instead of linked copies.

After tinkering a lot with the settings, here is how to get lots of objects aligned with a master axis (in the case of the images, Z).

The idea is to have an object you want to repeat over another mesh. This object should be rotated so that its +Z tip is actually pointing +X. Then you should use it as a Render Object in a Hair Particle System and copy the settings in the screen shots below. 

 

  1. Example with objects distributed with same rotation and scale.
Screen Shot 2016-02-04 at 01.37.39

 

2. Example with objects with random Scale.

Screen Shot 2016-02-04 at 01.37.46

 

3. Example with objects with random Rotation.

Screen Shot 2016-02-04 at 01.37.36

 

4. Example with objects with random Rotation and Scale.

Screen Shot 2016-02-04 at 01.37.33

 

With their method, we were effectively using memory optimisation, and complex scene with thousands of objects loaded almost instantly. 

Clamp with care

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Blender Cycles clamp setting is a saviour in hard to resolve fireflies, besides a myriad of other methods. Usage of clamp should be taken with care though, as clamping does not only clamp the high values of the mischiveous fireflies, as it also clamps the good brightness of the scene. Below, you can find a comparison between two renders with different clamp settings, with noticeably duller looks on the clamped one.

clamp01