Using Optical Flow under Bird''s-eye View Transform to Estimate the Height of Objects around a Vehicle

• Main Authors: Fung-Chan Lei, 雷丰銓
• Other Authors: Rong-Chin Lo
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/zh336d

碩士 === 國立臺北科技大學 === 電腦與通訊研究所 === 99 === The paper proposed a new method that can real-time estimates the height of objects with single camera from bird’s–eye view. Generally, it is impossible to obtain 3-D information, like the depth of objects, with one single camera except the additional information, such as the height of camera and the tilt angle of the camera, are known in advance. Although, the disparity map of the binocular cameras is usually employed to estimate the depth, but it is not suitable for a car to estimate the height (same as the depth estimating from planar view) of objects from bird’s-eye-view due to the difficulties of installation and corresponding. Therefore, the optical flow to estimate the height of the object with one camera is proposed. There are two features under dynamic bird’s–eye view of image. First, the optical flow value is proportional to the height of object. Second, there is no perspective effect in each layer height of image plane. Since the feature points between the obstacles and the ground are fetched and numbered, the ratio of optical flow of these 2 points is obtained. The camera’s height is known as well, therefore the height the of feature points can be estimated. In order to prove the proposed method, first, an experimental platform has been built, that includes one camera fixed on the platform and one 3*3 LEDs device. The LED device consists of three color LEDs where the height of red LED is 0 cm (i.e., on the ground), the height of yellow LED is 30 cm, the height of green LED is 60 cm. By using the camera, the continuous images of LEDs device per 10 cm movement under the bird’s-eye-view image is captured. From the captured images, the optical flows of LEDs (Red, yellow, green) in different height are calculated, then the heights of LEDs can be estimated. From the experimental results, the estimated LED’s height is very close to the actual LED’s height (5% error rate).