Remove stripes and grain from light and shadow

[Ghostwalden]

Hi to the light experts out there...

I have this stripes and grain on the wall and floor.

When i deactivate Cast Shadows in the light settings, then the stripes and the grain are gone.
But i also loose shadows, what's not the goal.

Setting Shadow Resolution to Very High, makes the stripes a little bit smoother.

Higher Shadow Strength makes the stripes go away, but i also loose shadow intensitiy.
But whatever i do, the grain consists.

Is there another way, to get rid of these stripes and the grain?

I have just a spot light in this scene, a VAM wall element and a cylinder on the ground.

 

[hazmhox]

Nope.

The grain is a product of the soft shadows, you can reduce it by using spots instead of point lights. And changing your intensity settings and distance of the light source. (either closer or further away, depends on the situation).

The stripes is a side effect of the angle at which the light is cast, especially for spots. The lower the angle is, the more the stripes will be visible. Your second shot shows exactly the case: your spot is close to the floor and projects light almost "parallel" to the plane (very low angle), if your spot was higher and the angle was more "direct" (between 60 and 90°) you wouldn't see them as much.

Also, both grain and stripes are more visible if the light settings are more intense. Improve your lighting by using more "reserved" settings and tweaking distance and the type of light instead. Unless you know exactly what you're doing or the effect needs to have intense values, in general, having subtle settings makes the light look better.

 

[hazmhox]

Side note: stripes and grain tend to be more subtle (or even not even visible) with detailed textures. The "banding" effect (just like on mp4 videos) in general, is always a problem on uniform colors. The moment you have a proper texture, the phenomenon is smoothed out : )

 

[Ghostwalden]

Thanks for the fast reply and the detailed information hazmhox

Hm... the spots
I guess i didn't notice this phenomen before, because i always used point lights.

Ok, then i will play around with distance, intensity and light settings, to see if I can achieve a satisfactory result.
I can imagine that the problem is mitigated with a proper texture
but especially for model presentation a uniform background is very pleasant.
There are probably a few good plugins that are helpful in these areas.
I'll have a look around in this regard.

 

[hazmhox]

Complementary note: having very soft shadow is not always a good move. The harder the shadows, the less stripes/grain you have. Very soft shadows are (in general) produced by very distant lights. For close light sources IRL, you don't see what your first shot shows with extremely diffused shadows, especially at that size and distance.

 

[SlimerJSpud]

There are a lot of cases where rendering in 3D exposes just how artificial it is compared to lights IRL. In 3D, when we use a point light, it really is a single point. There's almost no such thing as a real point source IRL. Any finite amount of surface area on the light source, like a bulb, or a tube, or a diffuser makes softer shadows. About the only case IRL where you see really sharp shadows is when the object casting the shadow is very close to the shadow. Either that, or you have a projection of a silhouette that is focused to have sharp edges.

In Daz Studio, people frequently use an invisible light that is a panel. You can stick it in front of a window to make some cheap light that pretends to come from outside. In Daz, we have real IBL, real HDRI, but Vam can't afford to take hours to render a single frame. Vam has to render in real time, so compromises have to be made. In Daz, having only an HDRI in the scene, and maybe one spot will render pretty quickly, but it's still seconds to minutes. No way to get 30-60 FPS out of that.