This paper dedicates to develop an algorithm which can be used to detect the real-time distance between the own car and the obstacle ahead. On the basis of comparing several existing methods

this paper uses the geometrical reasoning method to obtain the depth information of the driving environment for the vehicle control

and presents a real-tlme monocular-vision-based algorithm to get the distance between the own car and the obstacle ahead. The pitch angle of the camera is the key factor which affects the precision of the distance detection. This conclusion is drawn from the experimental results. In order to get the real pitch angle of the camera

the constraint that the two lane boundaries are parallel is used in the algorithm. The results of the static real-car tests show that the algorithm presented in this paper satisfies the precision requirements of the distance detection. And the results of the dynamic real-car tests show that the algorithm also satisfies the real-time requirements for the intelligent vehicle control.