Nathalie PESSEL
IFREMER
Zone Portuaire de Bregaillon
83507 LA SEYNE-SUR-MER
FRANCE
e-mail: Nathalie.Pessel@ifremer.fr
http://
Keywords: Self-calibration, intrinsic parameters,
fundamental matrix, matching, tracking, RANSAC.
This paper
presents a self-calibration technique for a camera mounted on an underwater
vehicle designed to perform the 3D reconstruction of underwater scenes. Our aim
is to identify the intrinsic parameters of the camera with methods that are
adapted to the operational constraints on Ifremer’s underwater vehicles.
The optical system is composed by a single
vertical camera located below the underwater vehicle and looking downwards. The
motion of the vehicle can be measured through navigation sensors and the
observed 3D scene is always unknown. The use of a moving camera is not an
obstacle for the application of stereoscopic methods. Nevertheless, the camera motion enables the use of robust
algorithms for points matching, but impoverishes perspective effects between
several images. Therefore, we are interested in the analysis of the conditions
in which the procedure of self-calibration is valid and reliable, i.e.: the 3D
characteristics of the scene and the camera motion.
This paper
presents the steps necessary for the camera self-calibration in an underwater
environment: the extraction and the tracking of features in several successive
images, the fundamental matrix estimation and the intrinsic parameters
identification. Several tests and results are presented.