  This paper reports the repeat-pass interferometric SAR results of Gaofen-3, a
Chinese civil SAR satellite, acquired in November 2016 and March 2017 from
Ningbo area. With the spatial baseline about 600 m and time baseline 116 days,
the coherence of the two images still achieve good enough to generate the
digital elevation model (DEM). During the InSAR processing, we compared several
baseline estimating methods and obtained a good flat-earth phase removed
interferogram map. By using the latest SAR interferogram filter and phase
unwrapping method we proposed, we improved the coherence up to 0.88 in urban
area and obtained a high quality DEM in Ningbo area. In addition, we evaluated
the elevation model by comparing with the elevation values extracted from SRTM.
And the result shows that accuracy of the elevation map is about 5 m (RMS) in
plane area and 22m (RMS) in mountainous region, which demonstrated that
Gaofen-3 has the powerful ability of repeat-pass SAR Interferometry.

Geophysics