Soft Shadow Effect Question

Started by WAS, December 05, 2020, 02:55:19 pm

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WAS

I was curious, I notice with stuff that's close the ground, like lets say a raised rock, the soft shadow effect doesn't seem to be present really unless the sun is low, that is unless I crank it up and ruin other shadows. So I wanted to know, at what distance limit is the soft shadow most prominent? And would it be possible to control this limit to have softer tight shadow boundaries?

Matt

Shadows from the sun and other direct light sources are calculated geometrically based on the size and position of the source, shadow caster and receiver. I guess this is what you mean, but this is simply ray traced and I'm not sure what extra control I could provide to make it do something different.

Skylight and indirect light may need to be rendered with the path tracer to create realistic shadows from them (as you know).

Our perception of these things can be affected by the relative amount of light arriving from different sources, for example if the sun is weak compared to the skylight then the soft shadow of the sky light will dominate and it will feel like the overall shadow is softer. If you want more local control to take advantage of that effect, you might consider adding some other local light sources and maybe partially shadowing the sunlight in your area of interest.

You could also try mixing in a second sunlight with a larger diameter to simulate a bright area of sky. This might render more efficiently (and maybe more realistically) than rays shot towards the sky.
Just because milk is white doesn't mean that clouds are made of milk.

WAS

I should try a second sun or light source with this scene that may help. I wanted a close up shot but found the shadows felt too hard. Granted on FS it's. Little hard to have uniform surface shaders (where areas get smooth cause of lateral disp, and not really modulatable (I assume a lack of geometry to work with).

But to that effect, like you mention with it being geometry calculated, a rougher surface that the shadows casts on helps this a lot I found. Not smooth sand like I wanted but at least it looks better. But curious about a second light source or sun.

Thanks for that explanation.