Image-based non-isotropic point light source calibration using digital fringe projection ...

Accurate light source calibration is critical in numerous applications including physics-based computer vision and graphics. We propose an image-based method for calibrating non-isotropic point light sources, addressing challenges posed by their non-radially symmetric radiant intensity distribution and the non-Lambertian properties of the calibration target. We deduce an image formation model, and capture the intensity of the calibration target at multiple poses, coupled with accurate 3D geometry acquisition using the digital fringe projection technique. Finally, we design an iterative computational framework to optimize all the light source parameters simultaneously. The experiment demonstrated the high accuracy of the calibrated light source model and showcased its application by estimating the relative reflectance of diverse surfaces. ...