The aim of this work is the investigation of camera-based techniques for distance estimation
between two autonomous vehicles. While both monocular- and stereo-camera
methods are explored, this study focuses on the usage of fiducial markers.
Therefore, existing fiducial markers are discussed and selected. Based on this selection,
three configurations of markers are proposed and applied to different distance
estimation methods. The chosen markers are AprilTag and WhyCon. Their distances
are estimated by means of Perspective-n-Point, 3D position calculation of a circle and
stereo-based triangulation.
Within this study the presented methods are evaluated based on their distance estimation
accuracy and applicable range. They are compared with each other and with
the common stereo method Semi-Global-Matching. Moreover, the influence of uncertainties
is explored with reference to geometrical calibration. A setup is presented
to evaluate the techniques based on real-world and simulated data. In order to gain
insights on the methods properties, a simulation is used that facilitates variation of
the image data. In addition, a Monte-Carlo-Simulation allows to model calibration
uncertainty. The obtained observations are substantiated based on two real-world experiments.
The results demonstrate the potential of fiducial markers for relative distance estimation
of vehicles in terms of high accuracy and low uncertainty. The lower sensitivity
to uncertainties in camera calibration makes fiducial markers preferable to stereo
methods
