Length measurements from monocular images

Length measurements provide important information about the three-dimensional world. This is especially useful for decision making in robot vision, path planning in autonomous navigation, and people identification in security application. In this work, we present a length measurement method based on perspective transformations using an uncalibrated camera. The theoretical principles are analyzed and the computational implementation is discussed. The usefulness of our proposal is verified experimentally by measuring relative lengths from experimental monocular images.