BRDFmodeller

BRDFmodeller is a software toolkit for modeling and fitting BRDFs. It provides tools to estimate BRDF parameters from measured reflectance data or to define analytic BRDF models and evaluate them across viewing and illumination directions. It supports isotropic and anisotropic materials and accommodates common microfacet and macroscopic reflectance models.

The toolkit offers model libraries including widely used forms such as Lambertian, Oren-Nayar, Phong, Blinn-Phong, Ward, and Cook-Torrance-type microfacet models, plus the ability to define custom models. It includes optimization engines for parameter estimation from data, with options for nonlinear least squares, robust fitting, and regularization to prevent overfitting.

Data handling features include import of measured BRDF datasets, coordinate normalization, masking of noisy samples, and validation through cross-validation or hold-out sets. It can generate BRDF lookups or parameter maps and supports exporting results to formats used by rendering engines, enabling direct use in physically based rendering workflows.

Visualization and diagnostics are provided, with plots of angular reflectance, residuals, and parameter sensitivity. The tool is designed for researchers and developers working in computer graphics, material appearance, and rendering, as well as for material catalogs and asset pipelines.