Noise in my IRAY Renders

Comments

• Richard Haseltine Posts: 108,052

  August 2015

  If a render stops before reaching 100% (whicb means whatever convergence percentage you set) then it hit the maximum time or sample-count first. Check your settings in the Progressive group in Render Settings.
• jdavison67 Posts: 689

  August 2015 edited August 2015

  Yeah, the biggest issue, which must be a new thing since last update, is the render time limit being set to a default of 7200 seconds. setting this to 0 allowed my render to continue.

  I had never hit this limit before the noise being less noticable, and the scene was one of the least complex I have done in a a while. 

  I'd post the result but the image is huge. I always  render at twice the size I need.

  You can see it here:

  http://damnedcomic.deviantart.com/art/Vogue-554113116

  I let the render go for 10 hours, and it was clean enough for me.

   

  Thanks for the advice!

  You were spot on.

   

  JD

   

  Post edited by jdavison67 on August 2015
• Richard Haseltine Posts: 108,052

  August 2015

  7,200 seconds (two hours) has always been the time limit, so there must be some other factor causing your renders to take more than two hours to converge now when they weren't before.
• Half Life Posts: 479

  August 2015 edited August 2015

  A couple of things that will cause the fireflies, which are easy to fix:

  1)  Your base color/texture should have no parts lighter than RGB 225 -- legacy textures will often violate this. The easiest solution is to set the color to RGB 225, however be aware this will darken all colors and may push the darks past the black threshold (generally nothing darker than RGB 40)... which will also give unnatural results. So editing in an external application may be needed.

  2) Zero roughness surfaces will cause noise (and look unnatural)  -- the general rule is the rougher the surface is, the less noise produced. This becomes more pronounced when low roughness surface are reflecting into each other (excessive bounces take longer to converge).

  Post edited by Half Life on August 2015
• Tobor Posts: 2,300

  August 2015

  Could you describe the "noise" Someone suggested fireflies, which are different from the "noise" caused by incomplete pixel convergence. Fireflies are nearly always white, and are aberrations in the physics of the rendering. Example: incompatible material types used for eye surface and cornea or pupil can cause fireflies to appear in the character's eyes.

  In case something in the Render settings has been altered, you could try resetting everything to the default -- start a new scene and hit the Default button on the right side of the Render pane. Load a single character -- G2F recommended for this test -- and use only the default "Ruins" HDR in the environment setting. It doesn't matter for this test if you leave the camera headlamp on.

  Apply the Optimized Iray G2F skin surface to the character, then do a nude non-hair render to a window about 900x900 pixels. Depending on whether you are rendering only with CPU, it should be fairly quick -- on my system with fewer than 500 CUDA cores such a render takes at most 5 minutes to reach 95% convergence.

  You mention the render stops before reaching 100%. What percentage are you looking at? The default *convergence* completion percentage is 95%, and rarely does it need to be adjust above that. As noted in Iray technical docs, there isn't much additional convergence in that last 5%, so going above the recommended maximum of 95% convergence is not advised under most circumstances.

  If you mean the progress bar at the top doesn't reach 100% before the render finishes, then the likely cause is one of those already mentioned: A) the scene has reached its convergence threshold, regardless of the "noise" you see, and/or B) it has timed out.

  Anyway, assuming your problems are related to slow rendering and timeouts, the above test is now your baseline. You can start adding scene elements to see which ones are slowing down the render.​