Two Case Studies on Vision-based Moving Objects Measurement
In this thesis, we presented two case studies on vision-based moving objects measurement. In the first case, we used a monocular camera to perform ego-motion estimation for a robot in an urban area. We developed the algorithm based on vertical line features such as vertical edges of buildings and poles in an urban area, because vertical lines are easy to be extracted, insensitive to lighting conditions/shadows, and sensitive to camera/robot movements on the ground plane. We derived an incremental estimation algorithm based on the vertical line pairs. We analyzed how errors are introduced and propagated in the continuous estimation process by deriving the closed form representation of covariance matrix. Then, we formulated the minimum variance ego-motion estimation problem into a convex optimization problem, and solved the problem with the interior-point method. The algorithm was extensively tested in physical experiments and compared with two popular methods. Our estimation results consistently outperformed the two counterparts in robustness, speed, and accuracy. In the second case, we used a camera-mirror system to measure the swimming motion of a live fish and the extracted motion data was used to drive animation of fish behavior. The camera-mirror system captured three orthogonal views of the fish. We also built a virtual fish model to assist the measurement of the real fish. The fish model has a four-link spinal cord and meshes attached to the spinal cord. We projected the fish model into three orthogonal views and matched the projected views with the real views captured by the camera. Then, we maximized the overlapping area of the fish in the projected views and the real views. The maximization result gave us the position, orientation, and body bending angle for the fish model that was used for the fish movement measurement. Part of this algorithm is still under construction and will be updated in the future.
Zhang, Ji (2011). Two Case Studies on Vision-based Moving Objects Measurement. Master's thesis, Texas A&M University. Available electronically from