3
$\begingroup$

This is a bit of a trick question. We know that HOLDOUT will subtract objects from renders. My question is slightly more elaborate. I had a render that I spent a fair amount of money on (render farm), only to find out that a material was set to the wrong settings. So I'm re-rendering the animation with every other object BUT the one I need using the HOLDOUT feature.

However, Blender is crawling all over the rendering even though 80% of the frame is 100% transparent. I'd love a way to have Blender only render the area where the object exists. I know about setting a render area method, but the problem arises where I need the object to be in the EXACT location that its predecessor was that had the material problem, so rendering the entire 4k frame is very helpful for a clean overlay.

enter image description here

$\endgroup$
  • 1
    $\begingroup$ Hello :). Since 2.9 there's adaptive sampling available. It should make transparent areas render very fast, since they don't need any samples. $\endgroup$ – Jachym Michal Oct 1 at 5:35
  • 1
    $\begingroup$ Thank you for this. I had seen this but didn't realize it affected this area. Much appreciated. $\endgroup$ – Dr Tyrell Oct 1 at 6:12
  • 1
    $\begingroup$ @JachymMichal Thanks! I hadn't twigged to that, either. $\endgroup$ – Robin Betts Oct 1 at 7:00
  • $\begingroup$ This took rendering times from 45 mins to 12 mins. Really amazing. Thank you again. $\endgroup$ – Dr Tyrell Oct 1 at 22:15
6
$\begingroup$

Since 2.9 you can enable Adaptive Sampling.
Transparent areas (or pure HDRI) are then rendered with 1 sample only.

enter image description here

| improve this answer | |
$\endgroup$
  • 1
    $\begingroup$ I had problems with 2.9.x corrupting my objects, so I pulled back to 2.8.3.6. I'm now using copies of my files to simply render. This was the key! 2.75 hour renders down to 30 mins. $\endgroup$ – Dr Tyrell Oct 3 at 0:45

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.