Pre-passes and Displacement for Animation

[Dippndots]

I recently noticed that when I send an animation to render with a separate prepass and render pass and I am using displacement, it has to calculate it in both. Is it necessary to have displacement enabled in the prepass if using it in the render pass? It would definitely be a big timesaver (~11min a prepass frame) if I didnt.

[maru]

Hi, what do you mean by "prepass" and "render pass"?

[Dippndots]

prepass is the backburner job that just generates and saves the UHD cache file every 25 frames (render time limit set to 1sec), the render pass job loads that and renders the image

[maru]

I don't think there is any way to overcome this. But maybe you could just render the final shot along with the UHD cache solution? So instead of rendering 1 image for 1s + 1 final, you would render only 1 final. Or maybe there is something I do not understand?

[Dippndots]

I suppose we could do that, it was just that when doing an animation, we only need to do the UHD calculation every 25 frames. Without the displacement it takes ~2.5min so we could save  that much time per frame over 150-400 frames.

Or do I have it wrong and are people not even bothering having a UHD "prepass" and just render animations with UHD set to the animation preset every frame?

[James Vella]

Im rendering some animations now. Didnt bother with cache just changed two settings in render dialogue (flicker free for animation and uncheck the static noise). Seems really nice so far... only a very slight "light pulse" in the dark shadow areas. Probably could get away with it 95% of the time. Im doing  some tests  this weekend with higher passes ill let u kknow if it is better

[Dippndots]

Yeah we've been rendering animations for a while now, but only just started using displacement. The UHD every 25passes works well but looks like its only worth doing it if you aren't using displacement.

[James Vella]

Hmm thats both coronamod and material?

[Dippndots]

Just in the material, haven't used the modifier much yet.

[Nariman]

have a flickering in the areas of displacement rendering with uhd precomputed
now testing with both engines set to path tracing
anyone has this issue? any suggestions?

[Dippndots]

have a flickering in the areas of displacement rendering with uhd precomputed

You mostly need to change the displacement settings in the performance tab of render setup from Screen Size(px) to World Size(units)