Simulating rolling shutter

[MrMetatron]

Hello

Is there a way to simulate rolling shutter like in Arnold... but in Octane? I'm being asked to provide renders by my ML team that need simulated data that looks like it has been taken with real devices like phones.

If there is a way to do it, please let me know. Alternatively, I could do it in post but I would prefer to do it in 3D.

Thank you.

[frankmci]

Off the top of my head, you could brute force it and physically imitate a rolling shutter: render 1080 individual 1x1920 pixel frames (or whatever fits your resolution) across the time of each frame exposure using an saw-tooth oscillating camera. Assembling the single pixel high frames in post should be pretty straight forward with an echo filter or the like. I've done slit-scan renders in AE this way. Yes, it's a boatload of frames, but little data/time per frame. There will definitely be some extra overhead that will make it render a little slower than full frames, especially if you use any post render effects. Seems doable.

There's got to be a more elegant solution, though.

[MrMetatron]

Off the top of my head, you could brute force it and physically imitate a rolling shutter: render 1080 individual 1x1920 pixel frames (or whatever fits your resolution) across the time of each frame exposure using an saw-tooth oscillating camera. Assembling the single pixel high frames in post should be pretty straight forward with an echo filter or the like. I've done slit-scan renders in AE this way. Yes, it's a boatload of frames, but little data/time per frame. There will definitely be some extra overhead that will make it render a little slower than full frames, especially if you use any post render effects. Seems doable.

There's got to be a more elegant solution, though.

Yes, that's a lot of images to render and because it ML (machine learning) related I would need to repeat the process a lot of times, so I don't think this is an efficient way to move forward. I love the idea and for some art projects I wouldn't mind give it a go . Unfortunately it won't be a viable solution for what we need. But thank you for the suggestion.

[frankmci]

I thought I'd try it, just to see, and it turns out that C4D won't let you render single pixel high images. The smallest you can do is 16, so that dog don't hunt. (Oh, in some ways I still miss you, Electric Image!) Octane Studio lets you go down to 4, which may be enough for the effect, especially if you add and overlay a pixel interpolated strip between each rendered strip in the assembled composite, giving a decent approximation of 2 pixels per progressive scan line.

My test render was wicked fast on a single 4090, rendering a moderately complex scene, 1920x4 pixel strips x 270 strips per frame, and rendered 1000 strips/4 frames in about a minute. I didn't set up the camera to do a proper vertical scan, though, just a simple orbit; I just wanted a feel for how long it would take. Maybe tonight I'll try the real deal.

It looks like this is a more practical option than I had expected it to be.