Distance and angle measurement of objects on an oblique plane based on pixel number variation of CCD images

This paper presents an image-based system for measuring target objects on an oblique plane based on pixel number variation of charge-coupled device images for digital cameras by referencing to two arbitrarily designated points in the image frame. Based on an established relationship between the displacement of the camera movement along the photographing direction and the variation in pixel counts between the reference points in the images, photographic distance and incline angle for objects lying on an oblique plane can be calculated via the proposed method. As a real-case application of the proposed approach, 2-D localization of target objects in robot soccer competitions is also demonstrated to show the effectiveness of the proposed approach. To allow the use of widely available digital zoom cameras for ranging and localization by the proposed method, a parameter equivalent to the displacement due to the camera movement is also investigated and derived in this paper.