Camera Self-Calibration Using Human Faces

Despite recent advancements in depth estimation and face alignment, it remains difficult to predict the distance to a human face in arbitrary videos due to the lack of camera calibration. A typical pipeline is to perform calibration with a checkerboard before the video capture, but this is inconvenient to users or impossible for unknown cameras. This work proposes to use the human face as the calibration object to estimate metric depth information and camera intrinsics. Our novel approach alternates between optimizing the 3D face and the camera intrinsics parameterized by a neural network. Compared to prior work, our method performs camera calibration on a larger variety of videos captured by unknown cameras. Further, due to the face prior, our method is more robust to noise in 2D observations compared to previous self-calibration methods. We show that our method improves calibration and depth prediction accuracy over prior works on both synthetic and real data. Code will be available at https://github.com/yhu9/FaceCalibration.