A Backward Pyramid Oriented Optical Flow Field Computing Method for Aerial Image

• Main Authors: LI Jiatian, LI Xiankai, LI Yingyun, QIAN Tanghui, LI Guojia, LIN Yan
• Format: Article
• Language: zho
• Published: Surveying and Mapping Press 2016-09-01
• Series: Acta Geodaetica et Cartographica Sinica
• Subjects: aerial image; optical flow field; backward pyramid; central projection; down sample
• Online Access: http://html.rhhz.net/CHXB/html/2016-9-1059.htm

Aerial image optical flow field is the foundation for detecting moving objects at low altitude and obtaining change information. In general,the image pyramid structure is embedded in numerical procedure in order to enhance the convergence globally. However,more often than not,the pyramid structure is constructed using a bottom-up approach progressively,ignoring the geometry imaging process.In particular,when the ground objects moving it will lead to miss optical flow or the optical flow too small that could hardly sustain the subsequent modeling and analyzing issues. So a backward pyramid structure is proposed on the foundation of top-level standard image. Firstly,down sampled factors of top-level image are calculated quantitatively through central projection,which making the optical flow in top-level image represent the shifting threshold of the set ground target. Secondly,combining top-level image with its original,the down sampled factors in middle layer are confirmed in a constant proportion way. Finally,the image of middle layer is achieved by Gaussian smoothing and image interpolation,and meanwhile the pyramid is formed. The comparative experiments and analysis illustrate that the backward pyramid can calculate the optic flow field in aerial image accurately,and it has advantages in restraining small ground displacement.