Estimation of Depth from Defocus for Micromanipulation Based onHigh Frequency Energy Parameter Eh
ZENG Ming1, ZHANG Jian-xun1, CHEN Shao-jie1, WANG Xiang-hui2, ZHAO Xin1
1. Institute of Robotics & Information Automation System, Nankai University, Tianjin 300071, China; 2. Key Laboratory of Opto electronic Information Science and Technology, MOE, Institute of Modern Optics, Nankai University, Tianjin 300071, China
Abstract：A new method of estimating the depth information for micro manipulation is proposed. The depth information is obtained by using high-spatial frequency energy parameters of the defocused images. The algorithm consists of two steps:firstly, the depth function is derived using a sequence of calibration images with an interval of 2μm; secondly, in the practical measurement, the depth can be calculated by using this depth equation when acquiring the energy parameter of the micro-manipulator in the certain position. In the testing experiments, the effect of micro glass needle shape on calibration experiments is analyzed and overcome. This method has been successfully applied to both ranging and rapid auto focusing in the actual micro-manipulation robot named NKTY-MR.
[1] Horn B K P. Robot Vision[M]. Cambridge:MIT Press, 1987. [2] Jarvis R A. A perspective on range finding techniques for computer vision[J]. IEEE Transations on Pattern Analysis and Machine Intelligence, 1983, 5(2):122-139. [3] Pentland A P. A new sense for depth of field [J]. IEEE Transations on Pattern Analysis and Machine Intelligence, 1987, 9(4):523-531. [4] Rajagopalan A N, Chaudhuri S. Space-variant approaches to recovery of depth from defocused images[J]. Computer Vision and Image Understanding, 1997, 68(3):309-329. [5] Ghit O, Whelan P F. A video-rate range sensor based on depth from defocus[J]. Optics & Laser Technology, 2001, 33(3):167-176. [6] Ziou D, Deschenes F. Depth from defocus estimation in spatial domain[J]. Computer Vision and Image Understanding, 2001,81(2):143-165. [7] Deschenes F, Ziou D, Fuchs P. Improved estimation of defocus blur and spatial shifts in spatial domain:a homotopy-based approach[J]. Pattern Recognition, 2003, 36(9):2105-2125. [8] 卢桂章,张建勋,赵新.面向生物工程实验的微操作机器人[J]. 南开大学学报(自然科学),1999,32(3):42-46. [9] 张建勋,薛大庆,卢桂章,等.通过显微图像特征抽取获得微操作目标纵向信息[J]. 机器人,2001,23(1):73-77. [10] Castleman K R. Digital Image Processing[M]. New Jersey:Prentice-Hall, 1996. [11] Stokseth P A. Properties of a defocused optical system [J]. Journal of the Optical Society of America, 1969, 59(10):1314-1321. [12] 黄大剐,卢桂章,赵新,等.微操作机器人系统的大范围三维标定方法[J]. 机器人,2002,24(4):352-357.
