Acquiring 4D Light Fields of Self-Luminous Light Sources Using Programmable Filter

Abstract

Self-luminous light sources in the real world often have nonnegligible sizes and radiate light inhomogeneously. Acquiring the model of such a light source is highly important for accurate image synthesis and understanding. In this paper, we propose a method for measuring 4D light fields of self-luminous extended light sources by using a liquid crystal (LC) panel, i.e. a programmable filter and a diffuse-reflection board. The proposed method recovers the 4D light field from the images of the board illuminated by the light radiated from a light source and passing through the LC panel. We make use of the feature that the transmittance of the LC panel can be controlled both spatially and temporally. The proposed method enables us to utilize multiplexed sensing, and therefore is able to acquire 4D light fields more efficiently and densely than the straightforward method. We implemented the prototype setup, and confirmed through a number of experiments that the proposed method is effective for modeling self-luminous extended light sources in the real world.