Do IRAY renders always converge the same pixels in order?

I was wondering... Say I rendered an image for 15 minutes. Then I rendered the same image for 15 minutes again and I compared them side by side or merged them. Would they have the same pixels not converged? I'm mostly curious because sometimes I have to stop a long render before it finishes converging and I wonder if I can just render it again andd composite the two to result in a finished product more converged than it's two parts.

 

Comments

  • Leonides02Leonides02 Posts: 1,379

    Yes, the noise will look the same if you stop it at exactly the same moment. 

  • TZORGTZORG Posts: 148
    edited January 2019

    Approximately the same pixels won't be converged, but that's because those pixels need more samples, not because it addresses pixels in a certain order. Rendering the same image on different computers for 15 minutes each (or whatever) is one way to cut down render times.

    Post edited by TZORG on
  • nicsttnicstt Posts: 11,715

    One (of many) things I see in Blender is the ability to changed the seed value; this puts the less merged pixels in different places.

  • TZORGTZORG Posts: 148

    I would assume you set the seed if you're deliberately trying to reproduce a result. In my experience, when you don't want it to be the same, you set the seed based on the computer's clock... Doesn't Iray do that? I'll have to test.

  • Iray uses a deterministic sampler so if the inputs are the same (same scene, materials, lights, render settings, samples, etc.) it should produce the same output for each pixel.

  • TZORGTZORG Posts: 148

    Ok, got it... Found a thread on it too: https://www.daz3d.com/forums/discussion/150021/randomize-noise

  • ParadigmParadigm Posts: 425

    I didn't search hard enough! That's the exact same question lol

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