flickering animation using irrmap/brute force

[stevesideas]

Hi guys,

Im doing an internal scene. There are moving objects in it. I have rendered out the entire animation initially using bruteforce/lightcache, but there was some bad flickering on the same parts of the render throughout the animation. I decided to just re-do these sections using irrmap/bruteforce, but there is still noticeable flickering. Any ideas what may be causing this.

Quick question. Should I be pre-calcing for these type of animations..whether im using lightache/bruteforce irrmap/bruteforce ? I was on the understanding that the calcs should be done on the fly when using brute force and there are moving objects in the scene....

I need to get these animations done before Monday...so any help asap would be really appreciated.

[natty]

Try this dirty workaround...

hide all moving objects
calc the light cache on fly through mode
from file for the light cache
unhide all the moving objects
now try rendering every frame with the saved light cache and irr map on single.. sometimes works, sometimes doesnt .. see how you go..

Natty

[stevesideas]

Thanks for the method..Im a little concerned about it sometimes working and sometimes not. I'll give it a go for a couple of frames. As long as there is no flickering and consistency then thats fine...

[natty]

Do some simple test first, like a chair moving in a simple room..

[natty]

im just doing a small test for you, with precalced static lightcache with object hidden, then object unhidden and using prepass animation mode.

[natty]

Hi

only a simple 5 min test but you can see it is flicker free, i don't know how complicated your scene is but this solution is worth trying.

http://www.rendertime.co.uk/animations/chair.avi

[stevesideas]

Cheers Natty. Rendering out now. Seems to be fine.

Is that how you do a lot of animations with moving objects ? You dont get the reflected GI back from the moving objects though do you...

[sv]

Hi guys,

II have rendered out the entire animation initially using bruteforce/lightcache, but there was some bad flickering on the same parts of the render throughout the animation. I decided to just re-do these sections using irrmap/bruteforce, but there is still noticeable flickering. Any ideas what may be causing this.

Can you post an example image / video of the result?
I'd hazzard a guess that it's actually not GI but bad geometry - maybe a co-planar faces issue. I say this because I use BF/LC constantly, and really don't suffer from flickering GI issues. Could you post your LC settings also?

(...check geo...)

[stevesideas]

I left the rendering going for the night and realised when bringing into aftereffects that the render is now quite a bit darker because the moving objects were not in the scene. They refelect a fair bit of light back onto some objects and using the method above cause the gi reflections to reduce.

Im going to check my geometry but I remodelled all the cad stuff so Im pretty sure it should be fine and without coplanar faces..

Edit: Ok, with a lot of masking and feathering I am able to get it to look ok.

My settings were:

Image sampler: Adaptive DMC
Min: 1
Max: 10

Antialiasing filter: area

Brute force: 12 subd's

Lightcache:

Subdivs: 1800
sample size: 0.02
Scale: screen
Store direct light: on
Pre-filter: 60
Use lightcache for glossy rays: on
Filter: Nearest
Int samples: 80

Global Subdivs: 1.0

[sv]

cool; glad it's working.

With the light cache, I normally leave all options off, and just set subdivs to around 1200-1600 in screen mode. I certainly would uncheck 'store direct light' if you are using BF+LC and have moving objects.

I would use fixed not nearest interpolation also.

But as always; it totally depends on the scene. there have been instances in the past where on static images, if the LightCache samples were bigger than 0.005 we got light splotches! So it is always scene dependent, but this setup has worked for me on every single shot of a job I have worked on for the last 6 weeks with no flickering at all in any renders...(and the light was mostly GI light bounced back off walls onto the objects, even though the walls were hidden from the camera -we mimicked the lighting of the shoot)

[stevesideas]

Do you think I'll have to precalc the lightcache again if I change the store direct light checkbox ?

[natty]

Yes you will have to

[stevesideas]

Oh BUM ! Oh BUM ! Oh BUM !

[natty]

Hows it going Steve?

[stevesideas]

Hi Nat..cheers for asking

Ive sent the renders to the clients farm. I think with a bit of careful masking via aftereffects things should be ok. Thanks again for the help.