In today's Blender 2.8 tutorial, I want to share a secret (or at least very uncommon) technique to make your Blender materials instantly better. It is called angular roughness (or fresnel glossiness etc.) and works both for Eevee and Cycles rendering engines.
As a Chocofur Team we're also working on a small Addon that could add this effect to your Blender materials with just a single click. To get the beta access to the Addon, drop us a message at: [email protected] (it's free!).
You can download the 3D scene used in the video tutorial here.
Nice! never noticed this effect! Nice realistic detail!
Thanks for the tutorial! I hope they could integrate this to work automatially the next 2.81 or 2.82 version.
The fresnel effect is in the principled shader, including fresnel is one of the requirements of physically based rendering. Notice that with the default principled shader when you are looking at the surface head on you get very little specular reflection, which increases as the Angle of Incidence increases, the effect is just far more dramatic when the roughness is lowered, as in reality. Furthermore the way fresnel is being applied in this tutorial is done incorrectly, fresnel affects the reflectivity of the surface, not the roughness. The roughness parameter in the principled shader, along with every other PBR rendering system, is a surface parameter, it is defining a physical property of the surface material and should not be view dependent. This can be seen in how the reflections shrink and loose their fuzziness when the camera gets close to the plane, this does not happen in reality.
Though, credit where credit is due, this technique is very visually pleasing and allows a lot of artist control, the end results look really great. However, you need to be aware that the principled shader does include fresnel, and this technique completely breaks PBR, which is generally poor form when creating materials, and creates very incorrect lighting.
Are you sure of what your are saying ? That it does not happen in reality ?
Look at this other video :
I implemented view dependent roughness in some of my shaders a long time ago and it's great on certain cases (mostly big flat surfaces, walls, grounds and ceiling)...
I'm confused. I thought the fresnel effect was pretty well know in PBR by now. And I'm also fairly sure it's built into the principled shader. You're only adding a second, more dramatic fresnel. I'd like an expert's opinion on the footage you shot.
Fresnel works all fine when it comes to the reflectivity (specular) change with your viewing angle. However, specular is not the only thing that changes, as the perceived roughness also decreases if you move closer to the surface. Depending on the surface type, this effect is more or less noticeable, but it seems no to be supported by default in the Principled BSDF node. And that's ok!
Could you link to some research papers on that?
Afaik we shouldn't even be talking about specularity when considering PBR. Specularity is an old method of faking reflections of point lamps. We're using raytraced reflections here.
I think roughness as well as reflectivity (is in: the diffuse/glossy ratio) are both taken into account in the principled shader. I think that the exaggerated fresnel you see in real life can be recreated in 3d without using your exaggerated setup.
Sidenote: I love chocofur, you helped me trmendously during my studies making quality renders with Blender.
Hi to all
I know very well the FRESNEL effect , developping myself my own 3D reders by XNA and MONOGAME , and I fear that you are talking about is not FRESNEL but just REFLEXIVITY with a special property on your material
FRESNEL involves a balancing between the REFLECTION and the REFRACTION. Example of water , glass , ice , etc ... you can see the reflection far away from you , or you can see the ground behind the surface , depends of the angle between "surface normal" and the "eye ray" or "camera ray"
Then we can't talk about FRESNEL without refraction in your example , you show only reflexion , function of the "face angle" you put in your shader.
To finish , I confirm that I see perfectly the FRESNEL in "Principled BSDF" , it works fine when for example [Transmission=1.0] and [Roughness=0.0] , excess values , we can see REFLECTION and REFRACTION if function of the point of view.
I hope my comment will help
Myself and a few others explored this in quite some detail on a Blenderartists thread back in 2017. The result of that thread was a simple nodegroup that could be plugged into the roughness slot of the glossy or principled shader.
I also uploaded a material using this nodegroup to Blendswap.