Calibration Method of the Monocular Omnidirectional Stereo Camera
This work addresses the need for compact and low-cost distance measurement devices in autonomous driving, representing an incremental improvement in calibration techniques for a specific camera design.
The paper tackles the problem of calibrating a monocular omnidirectional stereo camera for autonomous driving by establishing a new method that considers higher-order radial distortion, tangential distortion, image sensor tilt, and lens-mirror offset, resulting in a reduction of calibration error by 6.0 and 4.3 times for upper- and lower-view images and improving distance measurement errors almost nine times compared to conventional methods.
Compact and low-cost devices are needed for autonomous driving to image and measure distances to objects 360-degree around. We have been developing an omnidirectional stereo camera exploiting two hyperbolic mirrors and a single set of a lens and sensor, which makes this camera compact and cost efficient. We establish a new calibration method for this camera considering higher-order radial distortion, detailed tangential distortion, an image sensor tilt, and a lens-mirror offset. Our method reduces the calibration error by 6.0 and 4.3 times for the upper- and lower-view images, respectively. The random error of the distance measurement is 4.9% and the systematic error is 5.7% up to objects 14 meters apart, which is improved almost nine times compared to the conventional method. The remaining distance errors is due to a degraded optical resolution of the prototype, which we plan to make further improvements as future work.