Physically based rendering (PBR) is a computer graphics approach that seeks to render images in a way that models the lights and surfaces with optics in the real world. It is often referred to as "Physically Based Lighting" or "Physically Based Shading". Many PBR pipelines aim to achieve photorealism. Feasible and quick approximations of the bidirectional reflectance distribution function and rendering equation are of mathematical importance in this field. Photogrammetry may be used to help discover and encode accurate optical properties of materials. PBR principles may be implemented in real-time applications using Shaders or offline applications using Ray tracing (graphics) or Path tracing.
Starting in the 1980s, a number of rendering researchers worked on establishing a solid theoretical basis for rendering, including physical correctness. Much of this work was done at the Cornell University Program of Computer Graphics; a 1997 paper from that lab[1] describes the work done at Cornell in this area to that point.
"Physically Based Shading" was introduced by Yoshiharu Gotanda during the course Physically-Based Shading Models in Film and Game Production at the SIGGRAPH 2010. And followed by the course Physically Based Shading in Theory and Practice organised by Stephen Hill and Stephen McAuley between 2012 and 2020.
The phrase "Physically Based Rendering" was more widely popularized by Matt Pharr, Greg Humphreys, and Pat Hanrahan in their book of the same name from 2004, a seminal work in modern computer graphics that won its authors a Technical Achievement Academy Award for special effects.
The first successful, yet partial implementation of physically-based rendering in a video game can be found in the 2013 title Remember Me, that despite being built on a game engine not natively supporting this technology (Unreal Engine 3) was properly modified to accommodate this feature.Despite being a moderate approach to PBR, its accuracy has been further refined with posterior titles such as Ryse: Son of Rome and Killzone Shadow Fall, released on the same year, until the current state of PBR advancements in the 2020s.
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