Light Structure from Pin Motion:
Simple and Accurate Point Light
Calibration for Physics-based Modeling
Abstract. We present a practical method for geometric point light
source calibration. Unlike in prior works that use Lambertian spheres,
mirror spheres, or mirror planes, our calibration target consists of a Lambertian plane and small shadow casters at unknown positions above the
plane. Due to their small size, the casters’ shadows can be localized more
precisely than highlights on mirrors. We show that, given shadow observations from a moving calibration target and a fixed camera, the shadow
caster positions and the light position or direction can be simultaneously
recovered in a structure from motion framework. Our evaluation on simulated and real scenes shows that our method yields light estimates that
are stable and more accurate than existing techniques while having a
considerably simpler setup and requiring less manual labor