denoise on ground?

[andy.engelkemier]

Is there a way to denoise ground shadows? I tried with a ground plane as well, still no luck. It takes longer, but doesn't seem to be any different.
I ended up just using surface blur in Photoshop. But the noise pattern on the ground is really strong, and really annoying. I've never really been able to get rid of it. What am I doing wrong?

[Eugen Fetsch]

Did you try to switch off Ground Illumination? It helps if you don't need them.

[andy.engelkemier]

No ground illumination. No GI. No caustics. Just Self Shadows, shadow quality 5, and...well Ray bounces are at 96 because my entire model is invisible to camera so that I can render just the ground shadow.

[andy.engelkemier]

Well I figured it out.

I forget that Keyshot doesn't calculate sampling on alpha. AND the photographic image style is a post effect.
I'll explain. My environment background color was black. The shadow is black. But the Render comes out black shadow on White because I have the background showing white in the image style.

So it's a black on white image, but keyshot doesn't see it that way. It looks at the shadow, black, and looks at the background color being Calculated, also black, and says "well, I don't need anymore samples. That there is good." Although, it still goes ahead and calculates essentially nothing for quite a while. It sees no change after the first sample.

So to solve that you have to make your background color White in the environment. Now your shadow gets calculated on white. And Boom, denoise works so you can get away with only a few samples and render a shadow pass all by itself crazy fast.

I wish Keyshot had the option to sample against the alpha channel, but for now this works. I'm just using the black and white image to create a shadow layer in photoshop anyway. Because since keyshot forces you into rendering black shadow on white, the transparent values aren't black, they are grey. So you'll get "glowing" shadows. But if you render on black and transparent, then your shadows look like garbage.

[designgestalt]

hello Andy,
thanks for posting your solution...
I had this a million times as well and could never figure out, that it had to do with the alpha ...
I always tweaked the shadow in Photoshop ...

cheers
designgestalt

[andy.engelkemier]

Yeah I Really wish Keyshot gave you the option to include RGBA in the noise threshold. Vray hit that one right on the nail. You can give separate ratios for each o R G B and A. So if you're Just rendering a shadow, you can get it to do just one sample for each pixel, but sample the Alpha till it's nice and smooth. It's a shadow. It should be black. It's black plus whatever is behind it. If you're rendering on transparent it should be Black. Just black. Don't sample the color. It's black (unless you override it for some stylized reason). Just sample the alpha.

[Aeonjoey]

I feel like this is a virus lol, I've been using denoise nearly constantly, and then suddenly today - all ground shadows stopped being denoised. even with a new file, and adding a primitive geometry model, with a stock environment, all my shadows are noisy, but literally earlier today, they were smooth. I've emailed luxion tech support, hopefully they can help me.

[andy.engelkemier]

Make sure you environment background is not black. White will give the best results.
It might Look white, if you have it set white in the image tab, but it does the sampling before that. So if you have black background color, then your shadows will always look like garbage. It's not a bug, more than a poor choice in how they are sampling.
Honestly, keyshot should probably just change how it treats transparency altogether. There should be a choice (which should probably be default) to not have shadows include the background. Because currently, the way it treats shadows and transparency, the shadows are Basically useless unless you render on the same background color you intend to composite on top of. You rendered on white for decent sampling? Great. Now you have shadows that go from black, to medium grey, to black again. That'll look good on Nothing except white.

We just render shadows black and white only, then composite them together. You can just use the black and white as a mask to fill Actually black in Photoshop. In AE you can fix things a little differently since it gives you manual alpha control, where photoshop doesn't, without lots of steps. But you'll still be dealing with halos, so it's always nice to have shadows solo. But that really is a lot of extra work that shouldn't be necessary.

[Aeonjoey]

This for us is unsatisfyingly intermittent and I've just stopped worrying about it, and go about a couple of steps to just start over with a new file, including exporting my model set as a new .BIP file, creating a new blank file and importing the exported .bip into the new blank file. and that solves it for me. it shouldn't, none of this should work or not work, but it just does. what's CRAZIER is that I can import THAT file BACK into my original file and wow, denoised ground shadows! so I have no insight other than - it seems intermittent and gets stuck on stupid sometimes.

[andy.engelkemier]

Ha, that actually sounds plausible. I remember having some similar frustration, so I just started rendering the shadow all by itself. That way I can denoise in post, and also make the shadow....Actually black, instead of values of the background.