Abstract — The work described in this paper has been developed in the framework of the Integrated Project APALACI- PReVENT, a European research activity funded by the European Commission to contribute to road safety by developing and demonstrating preventive safety applications and technologies. This paper describes a new method for detecting free space in front of vehicles driving on highways. The described algorithm is mainly based on time correlation and Inverse Perspective Mapping (IPM). In order to improve the system robustness and reliability IPM has been modified to achieve sub-pixel precision and a new image stabilization method specifically designed to work on structured road is also proposed. The robustness of the method will be shown describing test results. Considerations on computational power requested by the algorithm are provided. Index Terms — Free space detection, image correlation in time, inverse perspective mapping, sub-pixel accuracy, image stabilization. I
