geometry

Camera Models, End to End: Pinhole, Lens Distortion, Calibration & PnP — with OpenCV

How a 3-D point becomes a pixel and back again: the pinhole model and intrinsic matrix K, the extrinsics R|t, Brown–Conrady lens distortion (a corner can move 62 px), Zhang calibration to sub-pixel reprojection error, and solvePnP recovering a 68-px-off pose to ~0. The math, three interactive labs, and runnable OpenCV in Python and C++.