Open images in new tabs and switch between them. Look at sphere's shadow terminator - the difference should be obvious.
Indeed, the transition between light and shadow is way softer in Fstorm. Much more pleasing to the eye.
How does the Vray alSurface shader does compare to this?
"The Fresnel effect is computed as part of the BRDF calculations (a.k.a. “glossy Fresnel”) and takes into account the viewing direction, the surface normal, and the light directions."
Isn't it related to this ? nothing to do with the diffuse part, misread what you wrote
Also, As far as I remember, Corona shader does not support glossy fresnel.
What's more, some users are experiencing strange atifacts with SSS here :
https://forum.corona-renderer.com/index.php?topic=18702.0Which seems to be the exact same issue descibed here :
VRay Skin Mtl: This uses a two lobe specular model with a sharp and broad reflection. It also uses Phong as the reflective BRDF. This model proved to work well in many situations, but at glancing angles, based on the way that it would cut out the SSS, could cause darkening. This is because the Fresnel effect is computed as a function of the angle between the viewing direction and the surface normal, ignoring the directions from which lights illuminate the surfaces.
alSurface: This model also uses a two lobe specular model. However, instead of using a smooth BRDF like Phong or Blinn, it uses a microfacet one. The Fresnel effect is computed as part of the BRDF calculations (a.k.a. “glossy Fresnel”) and takes into account the viewing direction, the surface normal, and the light directions. The user has a choice between GGX and Beckmann BRDF models. Based on the nature of the micro faceting, it can avoid the darkening effect at the glancing angles through retro-reflection. Additionally it does not cover the SSS at the same glancing angles.
source :
https://www.chaosgroup.com/blog/v-rays-implementation-of-the-anders-langlands-alsurface-shaderOf course, I might be totally misleading as i'm not a tech guru like some of you guys..
But there is one thing that bother me. We were experiencing some white halos on rough shaders some times ago. By looking at the examples here (
https://www.chaosgroup.com/blog/understanding-glossy-fresnel), it looks like a direct consequence of not supporting the glossy fresnel effect. It seems fixed now. But when i see that glossy fresnel isn't supported yet, i wonder if it has been fixed the correct way or with some workarounds (we have then seen some dark halos when the devs were trying to fix it, which strengthens me in my view that it wasn't done the right way).
Basically, initial implementation of the shader was good, it should be more reflective at grazing angles like it was doing
BUT this effect should also be affected by the roughness as more micro-facets are facing the camera (so less grazing angles)
on rough materials compared to shiny ones. If the whole thing is well implemented, angle affect should resolve by itself I guess.
fStorm split the HDRi into indirect and direct pass, and I think this is the reason fStorm has different shadow values.
That said, your statement totally make sense here.