Efficient Object Reconstruction with Differentiable Area Light Shading

In 3D object reconstruction from photographs, estimating material properties is challenging.We propose an inverse rendering method that uses active area lighting: as this provides a wider range of lighting angles per photo than point lighting, material reconstruction can be more accurate for the same number of photos. We compare area light shading with point lighting. With either mesh or 3D Gaussian splatting pipelines, area lighting can improve BRDF reconstruction and leads to +3 dB relighting PSNR over point lights, or need only 1/5 of the input photos for the same quality. We also compare area light shading with Monte Carlo ray tracing and with differential linearly transformed cosines (LTC) plus shadow visibility weighting. LTC can be faster, improving optimization times by 25%. In SOTA method-level comparisons, our approach improves material reconstruction, particularly for material roughness, leading to superior relighting quality.