Is it possible to render only certain segments of the camera?

I’m working on several renders, and Im trying to get creative in how to conserve resources on my resource constrained computing (I’m on a MacBook Pro, doing CPU render in cycles).

For example, I have 1 render, where I have an animation going, but only in a small segment of the scene. The rest is affectively a still image, being rendered over and over. It would be so cool if I could render a single still image, and then render the animated section of the screen, and combine them in a composite afterwards. It would save me soooooooo much render time.

I have another scene, that I’m trying to get in a smooth loop, and some segments finish the loop before others. It would be amazing if I could render them separately (They occur in different locations on the screen), so if I could do 130 frames in on section, 260 in another, and 1300 in another, and have them all sync up afterwards.

I have been trying to brainstorm in my head how I can pull this off without moving the camera around and effecting the viewing angle. I could very easily make 3 separate camera’s and have them focused on separate areas of the scene, but won’t that ever so slightly change the viewing angle, thus causing a headache later down the road?

Does anybody have any ideas how I can achieve this?

I did a similar test myself recently where I rendered a single still background on one layer and had an animated clock on another layer. Effectively you’re rendering a clean ‘plate’ and vfx-ing your subject into it with compositing. If your subject is moving in a way that creates changing shadows on the background, you can render your background first (minus your subject), then render out your subject with the environment objects as a shadow/glossy/indirect catcher only, and then you should still see some optimizations in your render.

Hopefully I’ve got this right, I’ve only done this kind of thing on rare occasions. Good luck!


Hmm that’s a clever idea, I’m going to have to try that. Thank you for the suggestion. Not quite what I was hoping for, but from google searching it’s not looking like I have much choice.

Just an update, I found out how to do this. It’s called "Border rendering, and can be done by Command + B

I was gonna suggest that, but didnt think it would be what you needed, sorry oops :crazy_face:

That’s also a good trick for stills, if you have a small area with a lot of noise, you can brute-force it and do the rest with low samples.

Glad you got it sorted , and thanks for updating the thread, it helps people in the future when they search.

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