Physically Based Rendering

INTRO

Modeling the reflection of light in a visually pleasing way has always been a problem in computer graphics. With photorealism being the gold standard for most graphical representations of things, most models have the goal of approaching that look. While the Blinn-Phong model has been used in numerous applications over the past due to its simplicity and low resource consumption, attempts were made to improve the visual appeal at varying costs yet no real replacement for Specular reflection in particular had been found that would esablish itself as the new standard until the concept of Physically Based Rendering appeared. With many uses in non-realtime rendering like in the CG movie industry, pioneered by Disney, there was also an overhaul of engines in the realtime rendering and game world.

PBR

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Comparison

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Comparison

description and stuff here

BRDF

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Reflection, Irradiance

what's visible and how

Physically based BRDF

positivitiy, energy conservation

Lambert Model(Diffuse)

very cheap yet visually sufficient, unlike specular.

Lambert Term

$$\Large{k_{spec} = L \cdot N}$$ L := light vector
N := normal vector

Cook-Torrance Model(Specular)

my model of choice

Cook-Torrance Term

$$\Large{k_{spec} = {DFG \over 4(V \cdot N)(N \cdot L)}}$$ D := Distribution factor
F := Fresnel term
G := geometric attenuation term
V := eye(view) vector
L := light vector
N := normal vector
more explanation

Code snippet

subtitle

more explanation here

Math snippet

subtitle

When $a \ne 0$, there are two solutions to \(ax^2 + bx + c = 0\) and they are $$x = {-b \pm \sqrt{b^2-4ac} \over 2a}.$$

IBL

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MATERIALS

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DEMO

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END

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