Randomise noise on repeat frames / 'Lock noise pattern'

[Neilg]

Is there a way to have vray behave as if lock noise pattern is unchecked and have it randomize the noise every time the same frame is rendered?

Right now unchecking it uses the frame number as the random seed to generate a new noise pattern, and if you are rendering an animation by batch rendering many cameras of the same frame (think the matrix bullet time moment), the noise pattern stays the same, and looks awful, and breaks temporal post production denoising solutions. Is there something I can type into the max listener that will change this behavior so it randomizes it every time a render goes off, giving the same frame varying noise patterns?

While I will concede that this is an unorthodox way of rendering something, it's quite important to render this particular thing in this way.

[hermit.crab]

I do not understand what you're trying to do. Mind if you create a simple setup with some instructions of what's occurring and what you wish to happen?

[piotrus3333]

now this is content I like with the morning coffee.
is looping the animation as many times as you have cameras a realistic solution?

[fixeighted]

Could you not simply have one main camera which jumps to each subsequent camera's position/rotation, thus having random noise per frame within one sequence?

[vlado]

You can additionally modify the random seed using the renderers.current.dmc_randomSeed property from MaxScript. Maybe you can write a script that would change the seed and re-render the same frame...

Best regards,
Vlado

[Neilg]

You can additionally modify the random seed using the renderers.current.dmc_randomSeed property from MaxScript. Maybe you can write a script that would change the seed and re-render the same frame...

Best regards,
Vlado

Thanks! I think I can use this.

I'm not sure how best to explain it to everyone else... It's like how they did the bullet time moment in the matrix - that was a hundred physical cameras designed to shoot at almost the same time to freeze motion along a path. that's what I'm doing here. The reason why i'm freezing motion and rendering from multiple cameras on the same frame instead of killing all the scene animation is to preserve motion blur. unfortunately, there's a lot of motion blur required on the objects that need to hold their path in space.

Taking a camera path, using snapshot to generate a camera per frame, then using renderstacks to set up a batch process to output all of those cameras in order on the same frame to the same folder, appending the filename with the camera name, takes like 5 minutes to set up and queue on deadline and the end result is a normal animated sequence. It's super easy. The only issue is temporal denoisers don't work - but now I think I can write a quick little script that generates a random number to update the noise seed and run that as part of the batch submission in renderstacks.

[Joelaff]

Note another trick to get this type of effect is to animate your objects for one frame (so they move subframe) and then repeat this motion in a loop. The motion blur remains present, though the objects don't move from frame to frame. Then you can animate your camera around static objects that are motion blurred. You may need to adjust the phase of the motioblur to get it just right. But this does work. I have done it many times in multiple 3d packages.

The advantage to this technique is that, unlike the slice of time rig used in the Matrix, etc.), you can also get proper motion blur on your camera's motion.

If you are holding on motion blur like this you may also want to use the motion blur settings in the render settings, rather than in camera so that you can adjust Shutter Efficiency and Bias to get nicer blur:
https://docs.chaos.com/display/VMAX/Camera

[Neilg]

Note another trick to get this type of effect is to animate your objects for one frame (so they move subframe) and then repeat this motion in a loop. The motion blur remains present, though the objects don't move from frame to frame. Then you can animate your camera around static objects that are motion blurred. You may need to adjust the phase of the motioblur to get it just right. But this does work. I have done it many times in multiple 3d packages.

I feel like with the amount of Tyflow, phoenix, characters, and various moving objects this would be a lot more work than the way i'm doing it... I'm also doing 5 frames worth of motion blur to exaggerate the effect. Camera move is slow so full frame blur can be done in post easily with timewarp in AE.

It's pretty useful being able to use the main scene without destroying all the object animation to set it up like that - this approach takes 5 minutes to set up and doesn't require any per-object editing. You should try this way next time!

[Joelaff]

Interesting. Can you explain the technique further?

Did you basically build a slice of time rig? I have used those on set many times; so I know what those are. Nightmare to actually shoot with... Alignment is terrible, exposure differences, flare differences, etc.

I usually can't use post motion blur due to transparencies and artifacts. But am certainly open to ideas.