Vision-based parking guidance with adaptive isometric transformation

A vision-based parking guidance system is proposed to help drivers parking their cars into parking space. The proposed system only relies on an embedded hardware and a wide-angle camera to capture images for analysis without steering sensor. This is a money-saved technique; moreover, it is suitable for used cars and after-market usage. In the system, input images are first transformed into top-view images by a homography transformation. Then corner feature points on two continuous images are extracted to match each other. The feature-point pairs are further pruned by a least-square error metrics. The remained pairs are then used to estimate vehicle motion parameters, where an isometric transformation model based on the Ackermann steering geometry is proposed to describe the vehicle motion. At last, the vehicle trajectory is estimated based on the vehicle motion parameters and the parking guidance lines are drawn according to the vehicle trajectory. The key characteristics of a parking guidance system are stability and precision; the proposed model is more proper than general considered models for image-based parking guidance system.