We present a mathematical framework for enforcing energy conservation in a bidirectional reflectance distribution function (BRDF) by specifying halfway vector distributions in simple two-dimensional domains. Energy-conserving BRDFs can produce plausible rendered images with accurate reflectance behavior, especially near grazing angles. Using our framework, we create an empirical BRDF that allows easy specification of diffuse, specular, and retroreflective materials. We also present a second BRDF model that is useful for data fitting; although it does not preserve energy, it uses the same halfway vector domain as the first model. We show that this data-fitting BRDF can be used to match measured data extremely well using only a small set of parameters. We believe that this is an improvement over table-based lookups and factored versions of BRDF data.
%0 Journal Article
%1 Edwards:ea:2006
%A Edwards, Dave
%A Boulos, Solomon
%A Johnson, Jared
%A Shirley, Peter
%A Ashikhmin, Michael
%A Stark, Michael
%A Wyman, Chris
%C New York, NY, USA
%D 2006
%I ACM
%J ACM Trans. Graph.
%K brdf energy_conservation
%N 1
%P 1--18
%R 10.1145/1122501.1122502
%T The Halfway Vector Disk for BRDF Modeling
%V 25
%X We present a mathematical framework for enforcing energy conservation in a bidirectional reflectance distribution function (BRDF) by specifying halfway vector distributions in simple two-dimensional domains. Energy-conserving BRDFs can produce plausible rendered images with accurate reflectance behavior, especially near grazing angles. Using our framework, we create an empirical BRDF that allows easy specification of diffuse, specular, and retroreflective materials. We also present a second BRDF model that is useful for data fitting; although it does not preserve energy, it uses the same halfway vector domain as the first model. We show that this data-fitting BRDF can be used to match measured data extremely well using only a small set of parameters. We believe that this is an improvement over table-based lookups and factored versions of BRDF data.
@article{Edwards:ea:2006,
abstract = {We present a mathematical framework for enforcing energy conservation in a bidirectional reflectance distribution function (BRDF) by specifying halfway vector distributions in simple two-dimensional domains. Energy-conserving BRDFs can produce plausible rendered images with accurate reflectance behavior, especially near grazing angles. Using our framework, we create an empirical BRDF that allows easy specification of diffuse, specular, and retroreflective materials. We also present a second BRDF model that is useful for data fitting; although it does not preserve energy, it uses the same halfway vector domain as the first model. We show that this data-fitting BRDF can be used to match measured data extremely well using only a small set of parameters. We believe that this is an improvement over table-based lookups and factored versions of BRDF data.},
acmid = {1122502},
added-at = {2015-10-08T15:38:31.000+0200},
address = {New York, NY, USA},
author = {Edwards, Dave and Boulos, Solomon and Johnson, Jared and Shirley, Peter and Ashikhmin, Michael and Stark, Michael and Wyman, Chris},
biburl = {https://www.bibsonomy.org/bibtex/26a4f353ada7d43d58c4f440fe4c2f11e/ledood},
description = {The halfway vector disk for BRDF modeling},
doi = {10.1145/1122501.1122502},
interhash = {359d03d3e7221658128681661a2464a9},
intrahash = {6a4f353ada7d43d58c4f440fe4c2f11e},
issn = {0730-0301},
issue_date = {January 2006},
journal = {ACM Trans. Graph.},
keywords = {brdf energy_conservation},
month = jan,
number = 1,
numpages = {18},
pages = {1--18},
publisher = {ACM},
timestamp = {2016-04-29T15:43:27.000+0200},
title = {The Halfway Vector Disk for BRDF Modeling},
volume = 25,
year = 2006
}