Comparison of Camera Calibration Techniques for a Portable Mobile Mapping System

A Mobile Mapping System (MMS) has been designed by the Intelligent Transportation Systems (ITS) research group at the Institute of Technology Blanchard town (ITB). This system detects, geo-references and evaluates road delineation data for the purposes of road marking maintenance. It consists of a monochrome stereo camera system integrated with a tightly-coupled Global Positioning System/Inertial Navigation System (GPS/INS), allowing stereo images to be acquired with navigational data, allowing for geo-referencing of detected road markings. An essential step in this process is the calibration of the cameras, and relates the pose of the two cameras to each other and a world co-ordinate system. Road markings must be evaluated from a 35 m range so the cameras are required to have a wide field of view. Traditional calibration methods supposedly require a calibration object that would fill most of the calibration images. This large field of view would require a calibration object of substantial size that would be impractical for the purposes of this portable system. This paper gives an overview of the MMS, explores the theory of camera calibration and then details two camera calibration techniques (using a three-dimensional calibration object and two-dimensional object). The accuracy of these methods is then evaluated using a ground truth experiment.