Accuracy improvements of near-field photometric stereo via light source calibration

Precise light source calibration is crucial for 3D shape reconstruction in near-field photometric stereo. Current calibration techniques face shadow issues due to uneven illumination and the limitations of the Lambertian emission model. We propose a method for enhancing accuracy in near-field photometric stereo through light source calibration and a specially designed target. The robustness of planar marks is improved to uneven illumination to avoid the shadow problem during target positioning. By densely sampling the light source emission field and fitting spherical harmonics basis coefficients, the prior-free calibration is achieved for anisotropic radiance intensity distribution. The experimental results indicate that the reconstruction accuracy of standard parts has improved by 30.04%. These results show that the designed target provides a flexible and accurate calibration for photometric stereo.