Quantitative Trimming for Ortho Imaging at Night by Onboard High Sensitivity Consumer Grade Digital Cameras

Abstract

Various kinds of cameras have been utilizing as onboard cameras in the construction of Intelligent Transport Systems. In recently, utilization of the high sensitivity consumer grade digital cameras at night is attracting attention from the viewpoint of avoiding the effects of sunlight and congestion of people and cars. However, due to the image taken by the onboard cameras is a perspective projection image, the image is projected small at the far from car and the greater the influence of the lens distortion the farther from the image center. In order to avoid the issues, lower part of projection image or a bird's-eye view image is used, but the imaging of the bonnet part due to the vehicle model and the tilt of the camera becomes a new issue. Furthermore, a bird's-eye view image at night has to be trimmed to coincide with irradiation range since the irradiation distance and range for headlight are limited. On the other hand, feature quantities such as vanishing points and feature points on the lane have been used for projective transformation from a perspective projection image to a bird's-eye view image, but the projective transformation based on the feature quantity is an ill-posed problem.

Therefore, this paper discusses the quantitative trimming method based on the projective transformation that does not depend on the feature quantities and coincide with irradiation range of headlight too.