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Questions tagged [fresnel]

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6
votes
1answer
83 views

“Artist Friendly Metallic Fresnel” reversible?

While implementing the "Artist Friendly Metallic Fresnel" paper by Ole Gulbrandsen (http://jcgt.org/published/0003/04/03/paper.pdf), I read that it is fully reversible: (section 2.3.2): for all r,g ...
7
votes
1answer
418 views

Why is the half vector not used in diffuse BRDF Fresnel calculations?

I am currently working with Earl Hammon Jr's Presentation PBR Diffuse Lighting for GGX+Smith Microsurfaces (now mentioned as [PBR, p.XYZ] and have read through (among others) Brent Burley's Physically-...
7
votes
2answers
501 views

Fresnel equation with incident angle, n and k as input

I've seen a Fresnel equation for calculating the reflection amount at incidence angle with n and k values defined. This formula usually comes up in relation to computer graphics, but I can't find this ...
7
votes
0answers
535 views

More accurate Fresnel approximation for a RGB-based Path Tracer

I'm writing a path tracer and, for the moment, spectra related data (spectral power distributions and spectral reflectance curves) are stored as RGB tuples. In the Cook-Torrance specular BRDF I am ...
6
votes
1answer
123 views

Equivalent of Fresnel law for determining transmitted/diffuse split

I understand that Fresnel tells us what percentage of light reflects vs refracts, but what law tells me the percentage of refracted light that is transmitted versus the percentage of refracted light ...
6
votes
1answer
373 views

Fresnel and specular colour

I'm trying to implement Cook-Torrance BRDF and had previously bookmarked this question as it looked very well thought out. Going through it, I'm confused about the Fresnel equation. The author has the ...
11
votes
3answers
818 views

What explains the high specularity of metals?

From my understanding, the specular color usually refers to the amount of light that is reflected when the surface is lit at normal incidence, and is noted $F_0$ or $R_0$. Moreover, for non metal ...
7
votes
2answers
834 views

In a physically based BRDF, what vector should be used to compute the Fresnel coefficient?

The well known Schlick approximation of the Fresnel coefficient gives the equation: $F=F_0+(1 - F_0)(1 - cos(\theta))^5$ And $cos(\theta)$ is equal to the dot product of the surface normal vector ...
16
votes
2answers
3k views

How to properly combine the diffuse and specular terms?

As far as I understand, in a BRDF the Fresnel term is telling us the probability for a photon to be reflected or refracted when it hits a surface. The reflected photons will contribute to the ...