I can't seem to get rid of the grain in the shadows of this scene I'm playing with. I've tried using the A-buffer, I've tried multi-pass 9 (3X3), 16 (4X4), 25 (5X5), and 64 (8X8) but it still renders grainy.

The scene is just set up w/ 2 lights, both suns, the one from the right is 100% w/ shadows (5 rays), while the front light is a 45% fill. I've even rendered w/ rays up as high as 40 (at 64 (8X8) multi-pass - attached) and it's STILL grainy!

Any suggestions? Why am I getting so much grain? What is the best way to reduce or remove this?
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A:M 14c

Thanks,

TommyDAQ

Are you rendering with Ambient Occlusion? Do you have a roughness value set for the floor and the letters?

I'm not rendering with Ambient Occulusion - I don't really understand what it is or does (same with subsurface scattering) - but I do have an open sky. The BG is just a decaled tube w/ a high ambient value.

As far as I know, there roughness set on the surface of the letters or the ground, unless it's set there by default. I haven't changed it, but I'll look.

How much do you really need true soft shadows?

I'd set rays to 1

and the width of the light to 0 for sharp shadows

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or set a large light width for fading shadows

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Roughness set to 0 on everything.

Does that work with Suns, or just Kliegs?

that's for any ray traced light. Kleigs can be raytraced if you set them to be that. Sun shadows are only ray traced

Thanks, I didn't know that (been away from this software for TOOO long). Anyway, I reduced to 1 ray and its still very grainy.

Wow- another good trick from Robert!

Just to throw out a few ideas, have you tried z-buffered shadows instead of ray-traced? And do you get that roughness when the camera is at a different angle, like less oblique to the ground plane?

how are you getting grain with one ray? Use the regular render not Multi-pass

Post a sample PRJ if you can.

You can use 1 Ray... this will create hard shadows (which shouldnt be grainy... be sure to uncheck "Distribute to Passes" in the Shadow-Options, just in case).
Dont use AO or increase the AO-quality-setting in the renderingsettings.

*Fuchur*

Ok, 1 ray, no multi-pass and shadows are solid - no grain! At least I'm getting somewhere! I may try setting to Klieg and rendering buffered shadows, but I'd like to be able to resolve this grain thing properly.

Client wanted something that resembled this:
http://www.youtube.com/watch?v=aUSj1LAmyGU

My file was just an early concept to show I could set up something similar - not much put into it yet, but the grain was really throwing me and I wanted to resolve that before I moved on...

Project is attached....
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Using more rays will make it less grainy too... but the renderingtimes are rising to...
For that kind of situation you could use Z-Buffer-Shadows... they can be made soft very easy, will render fast and willl not be grainy...

*Fuchur*

Don't you hate it when someone brings you something they want to copy? I had a manager who would do that all the time.

I think those could be z-bufffered shadows which will do soft without grain. However they don't do the penumbra thing without multipass.

Here's one very narrow Kleig, very far away, with a high "map resolution", with "softness" at 0, penumbra ON. Adjust the "width" of the light until the ends of the shadows are as non-sharp as you would like. In this scene it's 200cm (These settings I did in the chor BTW, not on the light in the objects folder)

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However, even with 9 passes the stepping of the jittered light is noticeable. You could go with more passes, or up the softness of the light until the blur is just enough to mask the stepping. This is 3

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this gets shadows that are semi-realistically sharp near the base of the model but fuzzier near the end.

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The basic trade offs are

Wider light needs either more passes or more "softness"

Fewer passes needs more "softness" to cover it up.

More softness means less realistic sharp shadows where the object contacts the ground.




Edit: sorry, I didn't see your sample PRJ or I would have used that.

Thanks! I think you guys have given me plenty to work with! I'll post final - if the project ever is a go!

Robcat2075 and Fuchur,

I realize that the original posts here are from a few years ago but thank you for these clear explainations.

I've been struggling with this same problem for years and I just came across your solution today.

This will help me alot.

Thanks again.

I looked at the first post and didn't realize how old it was and thought "damn... didn't we solve this a couple of years ago?"

No biggy... better to solve it at all than never...