Acceleration Structure Types


quick question - does changing the Acceleration Structure type in the Render > Performance panel actually change the look of the render, or does it simply use different math to analyze the normals and create the image?

i have a scene where if if i use “Auto” the render returns errors and gives me either a black or white render in the end. in other words, the render messes up and doesn’t render properly. i tried different revisions of Blender (builds from, builds from, and my own Linux build) on different platforms (Linux, OSX and Windows) but it did not change the outcome.

i was able to isolate the problem to a particular object on it’s own layer, noticed by viewing that layer in the compositor that it was returning yellow dots. i had read somewhere that yellow dots mean the ray tracing is missing / failing there, and so these dots are put in to help you troubleshoot the issue. i figured i would change the Acceleration Structure from “Auto” to Octree (resolution 512) and the render came out perfectly.

questions would be:

1.) any idea whether changing Acceleration Structures actually changes the look of the image? i don’t think it does, but sometimes it’s hard to tell.

2.) what is the difference between these Acceleration Structures?

3.) how do you know which one you should pick if Auto isn’t doing the job for you?

thoughtful answers appreciated. :slight_smile:

no,it shouldn’t be different, please file a bug report

actually let me correct this. it seems that, if i render a particular frame on my windows copy of Blender, or my Linux build, i get either an all white or all black result after compositing, regardless of what Acceleration Structure i choose. on my Mac, this may happen if i use Auto as the Acceleration Structure, but usually if I pick Octree (512) it will render properly.

any reason a Mac would render something Windows and Linux would not?