Velocity Estimation of Moving Targets by Azimuth Differentials of SAR Images

SAR 영상의 Azimuth 차분을 이용한 움직이는 물체의 속도측정방법

  • 박정원 (연세대학교 지구시스템과학과) ;
  • 정형섭 (연세대학교 지구시스템과학과) ;
  • 원중선 (연세대학교 지구시스템과학과)
  • Published : 2008.04.30


We present an efficient and robust technique to estimate the velocity of moving targets from a single SAR image. In SAR images, azimuth image shift is a well blown phenomenon, which is observed in moving targets having slant-range velocity. Most methods estimated the velocity of moving targets from the distance difference between the road and moving targets or between ship and the ship wake. However, the methods could not be always applied to moving targets because it is difficult to find the road and the ship wake. We propose a method for estimating the velocity of moving targets from azimuth differentials of range-compressed image. This method is based on a phenomenon that Doppler center frequency shift of moving target causes a phase difference in azimuth differential values. The phase difference is linearly distorted by Doppler rate due to the geometry of SAR image. The linear distortion is eliminated from phase removal procedure, and then the constant phase difference is estimated. Finally, range velocity estimates for moving targets are retrieved from the constant phase difference. This technique was tested using an ENVISAT ASAR image in which several unknown ships are presented. In the case of a isolated target, the result was nearly coincident with the result from conventional method. However, in the case of a target which is located near non-target material, the difference of the result between from our algorithm and from conventional method was more than 1m/s.


  1. Chong, J., M. Zhu, and G. Dong, 2002. Ship target segmentation of high-resolution SAR images, Proceedings of the 4th European Conference on Synthetic Aperture Radar, EUSAR'02, 2002, pp.693-969.
  2. Jose, M. B. D. and M. B. Dias, Multiple moving target detection and trajectory estimation using a single SAR sensor, 2003, IEEE Trans. Aerospace and Electronic Systems, vol.39, pp. 604-624, Apr.
  3. Lin, I-I. and V. Khoo, 2003. Computer-based algorithm for ship detection from SAR imagery, papers/lini/, April 2003.
  4. Wahl, T., Eldhuset K., and Skoelv A., 1993. Ship traffic monitoring using the ERS-1 SAR, Proceedings of the First ERS-1 Symposium- Space at the Service of our Environment, Cannes, France, 4-6 November 1992, ESA SP- 359 (March 1993), pp. 823-828.
  5. Rees, W. G., 1990. Physical principle of remote sensing, Cambridge University Press, Cambridge, UK.
  6. Curtis, W. C., Elaine, C., and Bryan, L. H., 2004. Performance assessment of along-track interferometry for detecting ground moving targets, Proceeding of 2004 IEEE Radar Conference, Philadelphia, April 26-29, 2004.
  7. James, K. E., 2003. The estimation of ship velocity from SAR imagery, Geoscience and Remote Sensing Symposium, IGARSS '03. Proceedings.
  8. Hein, A., Processing of SAR data, Springer, 2004.
  9. Madsen, S. N., 1989. Estimating the Doppler Centroid of SAR Data, IEEE Trans. Aerospace and Electronic Systems, vol. AES- 25, pp. 134-140, Mar.
  10. Gintautas, P., F. Meyer, H. Runge, P. Reinartz, R. Scheiber, and R. Bamler., 2005. Estimation of Along-Track Velocity of Road Vehicles in SAR Data. In Proceedings of SPIE, vol. 5982, pp. 1-9, October 2005.
  11. Eldhuset, K., 1996. An automatic ship and ship wake detection system for spaceborne SAR images in coastal regions, IEEE Transactions on Geoscience and Remote Sensing, vol. 34, no.4, July 1996, pp. 1010-1019.