superior orbit
3.This paper mainly studies the influence of the Synthetic Aperture Radar satellite Precise Orbit to the interferometry, including the basic principle of InSAR, the principle of precise orbit and the error analysis, the data form of satellite radar(ERS and ENVISAT ASAR) which relates about precise orbit and the data form of precise orbit which is provided by DEOS, the superior baseline model, Doppler parameter estimation, the introduction of baseline method, basic algorithm research and realization, the experiment result analysis.
4.Results Screw fixation through axis body and massa lateralis atlantis was performed in 10 cases and that through axis body and odontoid process in 11. VRT could clearly display full aperture of screw orbit, location of screw and angle of fixation and hence was superior to X-ray plain film and MPR.

