3

Is it possible to render only a portion of your image while leaving what was previously rendered in the same render slot?

For example, if you rendered an entire image, then wanted to render a small portion of it again while keeping all of the original render except the small portion that would be different?

Animatoring
  • 1,430
  • 3
  • 26
  • 38
  • I'm curious about the use case. If a part of the scene changes the whole render could theoretically be affected via global illumination. – John Dvorak Aug 08 '16 at 05:11
  • @JanDvorak I mainly use this method for testing. You're right about the lighting, it would normally change but that wouldn't matter at the time because you would just want to see what the small portion of the render would look like on the previously rendered image to compare them. The ability to render on top of a previous render helps with a faster workflow because you can do multiple tests of how a render would look against the original quickly without rendering for too long. I'm coming from Maya and it has this feature, it might be something Blender might want to add in the future. – Animatoring Aug 08 '16 at 14:38
  • Maybe related: http://blender.stackexchange.com/questions/48099/how-to-build-different-scenarios-in-the-compositor/48110#48110 –  Aug 09 '16 at 01:36
  • related: http://blender.stackexchange.com/questions/301/render-just-part-of-a-final-image-from-cycles –  Aug 09 '16 at 02:30

2 Answers2

4

Not on the same slot. Re-rendering will wipe the information from the current slot.

To save the previous render use a different slot (You might want to save the image to an EXR file).

To render only a section use the Border Render option (CtrlB), then you'd need to composite the new section on top of the old one using the compositor.

-1

I was searching for a similair problem, its not exactly your problem but i stumbled upon a answer. And people could have the same problem like I had and endup here so :

In case one would like to re- render an object in an animation (without rendering the whole frame), i would highly recommend this addon :

https://blendermarket.com/products/animated-render-border/

It tracks an object trough your animation and renders it with a border around it, so in Blenders video Editor, you could overlay your fixed object partial image over the wrong frames.

Peter
  • 2,344
  • 1
  • 12
  • 26