Abstract: A vehicle periphery monitoring system takes a view image of a vehicle rear periphery, which is in a predetermined area from the vehicle. This view image is converted into a bird's-eye view image and the bird's-eye view image is displayed in a vehicle compartment to assist rearward movement of a vehicle. As the vehicle approaches an obstacle, the bird's-eye view image is formed by increasing an angle of depression of the bird's-eye view image. A masking section is synthesized with the bird's-eye view image to mask a part of the bird's-eye view image not to be viewed. This masking section is increased as the depression angle increases thereby masking the distorted part of the view image.

Abstract: An obstacle detection system has multiple ultrasonic sonars. When a threshold value used for determining an existence of an obstacle is compared with a receiving signal having been amplified at a predetermined gain, the sonar having a receiving mode is provided with the gain which is higher than that of the sonar having a sending/receiving mode. Thus, the sensitivity of the sonar having the receiving mode can be improved so that a continuous sound field of the sonar is broadened. Accordingly, the distance of the border of the continuous sound field of the obstacle detection system from the vehicle can become substantially even.