Perspective-n-Point (PnP) is the geometric problem of estimating a camera's position and orientation from known 3D points and their corresponding image points. This article works through the projection equation, P3P/AP3P, EPnP, iterative optimization, RANSAC, planar degeneracy, and how PnP is used in Visual SLAM, AR, and surveying, with the math and an implementation checklist.
September 4, 2026 Computer Vision PrimerCamera calibration is the process of recovering the intrinsic parameters and lens distortion needed to map pixel coordinates onto 3D space. From revisiting the pinhole model, through radial and tangential distortion models, Zhang's planar-pattern method, reprojection-error optimization, to what breaks downstream in Visual SLAM and VO when calibration drifts — a systematic walkthrough with equations and diagrams.