A Multisensor Robotic Locating System And The Camera Calibration Problem

Abstract

A multisensor, microprocessor-controlled robotic locating system (RLS) is being devel-oped in our machine intelligence laboratory. A video camera, laser illuminator, optical angle sensors, and ultrasonics are the primary sensor components. Software is being de-veloped on a personal computer that has been augmented with video acquisition and high-speed signal processing boards. Real-time (less than 1 second) algorithms are being implemented that exploit both natural and artificial patterns. Artificial patterns are introduced by planting light-emitting diodes (LED) and reflective materials in the envi-ronment. Projecting light patterns is also part of the design. Using control points to determine camera position and orientation is a particularly interesting problem because of its apparent simplicity. Several algorithms for calibrat-ing a camera using control points are discussed in detail. The use of four control points in a rectangular configuration is especially detailed. A review of various approaches to camera calibration is included. The methods pre-sented are from the literature and work performed by the authors. These different ap-proaches provide insight into the nature of the problems. Closed form solutions are emphasized.