Dark Blotches appearing in renderings

[TSuess]

Ok. I have been having this issue for some time now. I get these dark blotches that appear almost exclusivley on the ceilings of my renderings. Usually I will fix them in photoshop but I'm doing a series of 360 frames for a camera pan across the room. It's way to much work to edit each individual frame. I've attached the image and my final gather settings. Any ideas or suggestions would be greatly appreciated. I have GI on w/ default settings.

 

Thanks,

T

 

[ATTACH]34455[/ATTACH]

 

[ATTACH]34456[/ATTACH]

[gsscott50@hotmail.com]

have you got GI turned on?

[TSuess]

Yes. GI on with default settings. From what I'm reading it's an interpolation issue. I ticked on 'Use Radius Interpolation method'. Kept the default settings. It seems to have worked on my test frame. I'll run the first ten frames from the animation tonight to see if it continues to work throughout all frames.

[gsscott50@hotmail.com]

Hopefully that works out for you. I was going to suggest putting in a higher value for 'max num photons per sample'. This usually sorts out most of my blotchy ceiling problems.

[Justin Hunt]

Sadly Radius interpolation doesn't work so nicely with animation.

 

Have you tried the Calculate FG from points along the camera path methode (Max2010 only).

 

I use this and the every nth frame fg calculation, saving to the same FGM. This gives really nice clean and detailed fg.

 

jhv

[TSuess]

I am currently using Max2009. We're looking into the upgrade now.

 

I rendered 5 frames last night, 3hrs per frame, rendered every 24th frame. and It looks pretty good. I had heard that the 'radius interpolation method' did not work with animations so I generated and saved the Photon Map but I generated a new FG map for each frame.. added to the render time but I think it's my only work around right now.

 

I am going to run successive frames tonight... 1,2,3,4,5.. I will try to re-use FG, and see what happens. Alot of people have told me it won't work but I want to test it first hand and see why it won't.

 

See below. The re-rendered image with 'Radius Interpoloation Method' checked.

 

[ATTACH]34471[/ATTACH]

[Justin Hunt]

For animations (and in general too) you can have really low FG settings, like draft. Set the inperpolation up to 100

 

The lighting detail will come from the Photons, which can be quite high in value.

 

An other tip to speed up rendering with Photometric lights is use the attenuation fall off. This limits to distance that the shadows are calculated.

 

jhv

[TSuess]

Thanks Justin. I'm running some test renders now. The animation looks fine calculating FG for every frame. Any other tips on reducing render time are greatly appreciated. I'll post results soon.

 

Tom

[pixelperfectg]

FWIW, I noticed that you've configured the noise filtering (Speckle Reduction) to it's highest setting...you should NEVER increase that beyond the default value of standard. In some scenarios it's good to disable it, otherwise I'd strongly recommend leaving it at the default setting. Why? You're eliminating a lot of bounced light in your scene when you increase that beyond "standard".

[Justin Hunt]

I also notice that you have the FG bounces @4, they are automatically discarded when using Photons so leave it @0

 

jhv

[TSuess]

Thanks all, I've made the adjustments. I'll run a few frames tonight. I'll repost images tomorrow morning. Thanks again for all the great advice.

 

Tom