IGI: BRDF from
Direct Illumination
Li = (ρd/π + ρsK(α,Θi))Ii
Li is the radiance
§Ii is the
irradiance
ρd/π is the diffuse term
ρsK(α,Θi) is the specular term
α is the parameterized surface
roughness
§Θi is the azimuth
of the incident and viewing directions
§The data from the images
collected we can solve the nonlinear
optimization problem and get parameters for ρs, ρd and α
§The radiance image must
cover an area with a specular highlight or we
will not have enough information for
recovering the specular parameters.