Any tips for rendering an animation with a still camera?

[Neilg]

I'm rendering an animation with a still camera of a very glassy building - there's 3 time lapses in use - the view (seen in glancing reflections/refractions), one behind the camera and one for the hdri. The camera doesn't move at all - the whole thing is static.


Is there any way to speed this rendering up? Like, re-use the anti-aliasing? I don't know. It's so slow having to re-render every frame and I feel like there must be a way to break this up i've not considered yet considering no edges move.

Lighting is being handled by IR animation mode and single frame LC - it's stable, just slow. Tried changing the hdri to a direct dome light but it didnt help much as I need GI for the interior lights and the sun bouncing around inside as it sets.

Is it possible to split this up into passes, where I do raw diffuse, reflections etc with no GI and the footage, then render the GI on a flat grey and apply it over the textured/reflecting model? I'll have to render the glass separately then too, but it might be faster... However I don't know if that will even work.

[Slazzo]

You could split scene in parts, and render them aside optimizing each as much as possible and then comp together. It's all subjective to project and animation type.

Doing stills for mostly everything, and render then pass for only what has to be animated.

[Neilg]

it's a 24 hour timelapse hdri. reflections, sun moving, colors changing...

I'm going to spend tomorrow doing some tests into rendering the raw diffuse & reflection etc with no GI and using the GI pass from a scene with no reflections. May not end up faster, but it's worth a go.

[Morbid Angel]

Man I'll save you the time right now by saying, don't waste your time on it Just let the computer do the job and go surf the web or something... I mean nothing wrong with doing some tests and experiments, but I found after many such tests, that it takes a lot more effort to create something that's marginally faster, then just turn on the render and let it go. Of course if you have lack of render power or pressed for dedaline its a different story, but it sounds like in your case, the animation (time lapse) is a fairly complicated dynamic effect.

Btw what are your settings? perhaps this could be improved.

[Neilg]

Man I'll save you the time right now by saying, don't waste your time on it Just let the computer do the job and go surf the web or something... I mean nothing wrong with doing some tests and experiments, but I found after many such tests, that it takes a lot more effort to create something that's marginally faster, then just turn on the render and let it go. Of course if you have lack of render power or pressed for dedaline its a different story, but it sounds like in your case, the animation (time lapse) is a fairly complicated dynamic effect.

Btw what are your settings? perhaps this could be improved.

Marginally faster does mean quite a lot here... it's 2500 frames at 4k
Resolution is lower than that and being scaled up - i've already done testing to find a compromise in image quality there.

Will be setting it up for final later, but settings are low - dmc 1,5 - .01 noise threshold etc. It renders in 40 minutes with single frame GI - it's when using the animation prepass/rendering and loading from 5 IR maps it doubles.
I need the GI for the sun/hdri - but I don't need it for the interior lights. Is there a way to completely exclude them from GI? This is kind of why I wanted to split it up.
Rendering without any glass and rendering that fully reflective with a falloff in the extra tex should help, need to figure out exactly how much by though.

Edit: the version with no gi took significantly longer than the one with GI. god damn it. that's not going to work.

[Slazzo]

for some reason I'm sure that the settings are the cause, rendering without GI shouldn't be longer from my experience, only if AA is having hard time refining the samples from lights or reflection/specular... wich is happening in both cases but in shadows can be difference.

I would go with fixed AA, something up to 4, in some cases even 1 can work fine for static geometry, then increasing the subdivs will not necessarily increase the render time but will clean up most of the things, next I'would find a good balance between lights vs glossy reflections and speculars, and then not much left to optimize, precalculated GI doesn't affect much rendering times, so I'll make sure checking the HDRI map and light emitter, to see if there is anything else to optimize.

But in most cases I found AA to be the time sucker. Unfortunately no more ideas from me.

[Neilg]

Precalculated GI does take longer if you're using animation mode and blending 5 frames together.

I'm using 'use light cache for glossy rays', so that probably explains the speed difference with gi on/off.

Thanks for the pointers. The experiments continue
I've got until the end of the week to finish this so I can afford to experiment a little and maybe learn something new. Rendering it over the weekend and spending a day setting up passes is prefrable to it taking over the farm for the entire of next week too.

[Neilg]

For an update, after numberous tests i've found the quickest method. I'm doing the base render every 25 frames and blending them, the glass as a seperate fully reflective pass (black mirror material, no GI) with a falloff in the extra tex to rebuild it, and i'm taking a small area of the backround, blurring it and overlaying it onto the render to catch the quicker changes in light.

Down to a total of 200 rendering hours
Rendering every frame was shaping up to work out at close to 4,500...

[Svetlozar Draganov]

You have saved 4,300 hours That's a very good optimization !