The three-dimensional visualization of a quasi-stable flow field needs two-dimensional projections. In flow field interferometric tomography, the conventional method of fringe tracking, by which a few solitary one-dimensional projections are obtained, can only evaluate the 2-D distribution of the field on a limited number of cross-sections. A new method combining the Fourier analysis and the improved multigrid iteration is proposed to extract 2-D projections from interferograms of the measured field in various directions. On the basis of 2-D projections the real 3-D field reconstruction can be reached. In the last section of this paper, an experiment of asymmetric temperature field measurement using rotaryF-P interferometer is reported and some cross-sections of the reconstructed temperature field are given to prove that the methods of sampling, processing and reconstruction algorithm illustrated in this paper are effective.