Uncalibrated active affine reconstruction closing the loop by visual servoing

This paper presents a new approach to active affine reconstruction without an exact knowledge of the robot’s kinematic model nor camera intrinsic parameters. Affine reconstruction from perspective image pairs is easy if the motion of the camera between the two images is a pure translation. If the robot is not well calibrated, a pure translation achieved with an open loop control would lead to a bias in the reconstruction. The problem can be solved by using a 2 1/2 D visual servoing technique in order to close the loop and control the camera trajectory. The affine reconstruction is equivalent to the estimation of the depths of the 3D points of the scene. Thus, affine reconstruction is very useful to implement several visual servoing approaches which need an estimation of the depths.