This paper applied prominent points’ information based on multi-PPP to compensate specific phase errors in spotlight SAR imaging.Among these points

the first one removes the phase errors from relative translation and produces a new focusing center

the second one is used to transform the rotational motion from unevenly to evenly

and the third one estimates the corresponding azimuth scaling factor.After this compensation

not only the space-invariant phase errors but also the space-variant phase errors are removed and high-resolution SAR images can be produced.It’s also analyzed that in PPP the second point can’t be processed independently of the third point in order to correct precisely motion errors from spotlight SAR images with PFA.How to select the prominent points so as to improve PPP is also suggested in the paper.At last the method is proved to be feasible by the simulation results when PPP autofocus is embedded in spotlight SAR imaging with PFA.