Strange Pattern in Shadow

[al_jot]

Hello Keyshoters,

I am using Keyshot pro 6.2.85 on a windows 7 hp z420 machine.
I have some issues with strange patterns in my shadows (see attached renderings)
I tried to crank up samples which had no effect.
So I leveld up the shadow quality to "10", which reduced the patterns, but resulted in an increas of rendertime by 600 percent.
Especially for big renderscene or animations, such an increase in rendertime is a big problem.

Is there any other way or trick to get rid of these annoying patterns?

[bdesign]

Hey-

Try using the Max Samples or Max Time options in the Render dialogue. Also, you can increase samples on a per material basis (for the Paint material which you are using in this scene, click the little arrow to the left of the Roughness parameter to access the samples value slider). Attached below are a few renders of your scene, all of which have the Paint material samples value at 16, the Shadow Quality under the Lighting tab>Settings at 2, and running 75% CPU usage. When using the Max Samples or Max Time options, KeyShot will use the render settings you set under the Lighting tab. I've put the specifics for each render in the image titles. As well, when creating white materials, it is advisable not to exceed about 90% (RGB 232,232,232), as pure white doesn't exist in reality. Also, I think the large scale of your cube may play a part in the noise; it is 13,000+ cm, which is approximately 43 ft. Hope this helps.

Eric

[al_jot]

Hi bdesign,

thanks for you reply and tips.
As you can see, i have no problem to get rid of the patterns. (see "shadow quality 10")
And unfortunately, the large scale has no influence on the shadows.

My problem is the enormous increase of rendertime to get an acceptable quality  for a "basic" material (if you set the white paint to default white diffuse material, you would get the same problems)

For instance, with default rendersettings, the cube renders about 13 s on my machine. By setting shadow quality to, let's say 10, to get rid of that pattern, my rendertime increases by factor 6.

That means, an Animation, which renders 1 day by default, would take 6 days. And there are no fancy materials applied yet, just diffuse white.

Is there any other trick to reduce the pattern, without rocketing the rendertime?

Thanks

[Chad Holton]

You may be able to getaway with less quality shadows when doing an animation. As Eric mentioned, try using max time or samples when rendering to find the sweet spot. I recommend max samples for consistent quality between frames. What you can do is setup your real time window to the same animation resolution size and let it bake . Turn on the HUD and when you're happy with the shadows, take note of the samples and use this value when offline rendering (max samples).

[Finema]

It's perhaps a problem with your model ?
because i can't reproduce your strange pattern with a native Keyshot cube

[al_jot]

Thanks guys.

@finema: just try harder . No just kidding. Unfortunately it is not a model problem. I can reproduce these patterns with native cubes as well.

@chad Holton: I won't get away with less quality shadows in animation. These patterns are static while the rest of the film is moving. This looks very strange, like you have put a second static patterned layer on top in afereffects.

As I mentioned before, I don't have problems to get rid of these patterns. Setting up the shadow quality to 5 and higher will do the job, and will result in a similar rendertime like max sample.

I'm just wondering, why you don't get a reasonable quality to rendertime ratio for a really basic (diffuse) material.

I played around a bit. For me, it is an occlusion issue.If you have one cube, no ground plane and "ground shadows" on, the pattern is gone.
If you place two objects next to each other with no groundplane and "ground shadows" off,  the pattern is back.

Maybe some of the keyshot guys can have a look at this and tell me, if this is a bug, which can be removed somehow, or that I just have to deal with it, that my white on white animation takes longer than anything else I was rendering till now.

Thank you,

Alex