Stereo camera pair calibration for traffic surveillance applications

calibration, stereo matching, sub-pixel registration, stereo vision, traffic
surveillance

We proposed an innovative stereo camera pair calibration method suitable for
traffic surveillance applications. In the method, we first split the sought
parameters into two groups. The first group contains parameters that can be
computed prior to the device being installed in the desired location, and we
determine their values using already established methods. The second group
contains parameters that need to be evaluated after the device is installed
on-site, and we utilize calibration vehicles for their evaluation. We first
localize the calibration vehicles by detecting and tracking their license plates
in a series of stereo images; afterward, we exploit the known information about
their speed and acceleration to compute the distances that they traveled between
two frames; finally, we determine the internal and external stereo camera pair
parameters by minimizing the difference between the computed and estimated
distances while preserving the epipolar geometry. We evaluated the presented
method on a task of measuring the distances that vehicles traveled between two
consecutive frames. For this evaluation, we recorded a dataset containing almost
700 vehicles with trajectories that were recorded using prototype hardware and
ground truth distance measurements that were obtained from a pair of single-beam
LIDARs. The evaluation results were compared with the current state-of-the-art
methods for long-distance stereo camera pair calibration and used in the
application of the proposed method on the vehicle speed measurement task.