Linear Estimation of 4-D Illumination Light Field from Diffuse Reflections

This paper proposes a linear estimation method for 4-D illumination light field using an inverse lighting framework. Although lighting environments have conventionally been modeled by the combination of point light sources or a spherical light field map, complex light sources such as an ordinary flashlight with lenses and reflectors, can not be correctly modeled by these approaches. In order to correctly model these complex light sources, we employ 4-D illumination light field. Unlike conventional work, we decompose observed intensities on a diffuse-reflection board into intensities of 4-D light rays by solving a linear system. We validate the effectiveness of the proposed method through the experiments on real and virtual environments.