low level light splotches

[Guest]

I'm using IR/LC and I have used the animation rendering/animation prepass method to render out an animation that has moving objects and light changes.

To start the animation has very little no no lighting and then the lights slowly turn on. But as they turn on there are very visible splotches which fade away when the room becomes fully lit.

What settings would I need to tweak to make sure I don't get any splotches in low level lighting?

I have:

dmc image sampler 1/16 clr thresh 0.005
IR map medium animation setting
Light cache 1200 subdivs scale world sample size 150mm

Both GI engines have use camera path on.

[leehumphries]

Hi james..

What interpolation settings are you using. Im sure there's loads of things it could be.

- Light subdivisions ?

[vlado]

What are the hemispheric subdivs for the irradiance map?

Best regards,
Vlado

[Guest]

Medium animation preset so 50 hemispheric subdivs 20 interp samples, then on animation render i reduced the interp samples to 10 anything lower just produced constant blotchy renders no matter what level the lighting is, changed interp frames to 4. Light subdivs are 28, material subdivs are around 20 - 32 depending on their glossiness, even materials without glossy are blotchy at low level lighting. When rendering a still image without the animation prepass i do not get any blotchyness when there is low lighting using the same settings.

The lights do go from 0 to 30 on the multiplier over 5 frames, as the multiplier gets to about 5 when you start being able to see what's in the room everything is blotchy. But on the plus side there is no flickering

[Guest]

here is the scene you can clearly see the blotchyness on the low level one

[flino2004]

try reducing color Thres. under IRmap (default value is .3 or .2 for medium animation I think) ...I did a test before for an animation and I didn't get spotches.

Fernando

[Guest]

Can i reduce the colour thresh after I have done the animation prepass or will I need to re render the IR prepass? what settings can you tweak after the prepass if any?

[flino2004]

i think you have to re-render them again.. you can do a quick test
the spotches can come from lc, working with world scale is not easy because depending of the scene and that information is used by Irmap.

[Guest]

Ok I have put all settings up high and chosen animation high preset for the IR map re rendered the pre pass and still at low level lighting the result is crap

[vlado]

Ok then; would be best to get us the scene or part of it to vray@chaosgroup.com so that we can figure out what's wrong with it. Also, what are the dmc sampler settings (in the system rollout)?

Best regards,
Vlado

[Guest]

OK I will send it today, If you could also look at why the result renders blue that would be great. The first time i calculated the pre pass teh result was splotchy so i upped the settings and rendered the prepass again but this time round the result was blue

How many IR maps would you like me to send with the file?

[vlado]

Depends on the interpolation frames parameter, you mentioned it is 4, so five maps before and five maps after a frame that has the issues should be enough.

Best regards,
Vlado

[Guest]

I managed to fix it, I had "show samples" ticked by accident on the Adaptive DMC sampler which in turn gave me a blue render. I managed to clear up a lot of splotchy areas by upping the max subdivs of the DMC sampler and removing "use light cache for glossy rays". Also keeping the IR map preset to high and when rendering I had the interp frames at 12 (originally at 20) any lower than that produced splotchyness.

Managed to get the render times down to 20 minutes a frame instead of 1.5 hours when using brute force.

Thanks for your help

[vlado]

Ok, good to know

Best regards,
Vlado