| dc.description.abstract | Interferometric Synthetic Aperture Radar (InSAR) is known as a useful technique for monitoring earth surface. One of the common applications is topography mapping. For a repeat-pass spaceborne radar system, conventional InSAR approach is limited in achieving high vertical accuracy owning to its inherent properties, such as different sorts of decorrelation, atmospheric delays, scattering properties, surface deformation, and geometric distortion. These are factors that contaminate final results during the whole imaging system, which makes it a sophisticated challenge to explore the drivers and their exact influences. The aim of this work is to discuss the impact from surface deformation and tropospheric delays on end topography products based on mathematic description. In order to alleviate the influence of phase unwrapping error, coherence masks are applied during InSAR processing. Therefore, the effectiveness of coherence masks is also one topic that is concerned in this research in addition to the discussion of the error analysis.
The result has shown that the application of coherence mask can improve the accuracy of measured heights for about 89% image pairs in our experiments. Also, the occurrence of phase unwrapping errors can be significantly reduced as the threshold increases. However, the precise reason for how coherence mask influence phase unwrapping remains a question. It is difficult to observe a consistent influence of coherence thresholds in low coherence areas, such as rivers and hills, while the influence in high coherence area is subtle. In error regression analysis, some significant correlations between the errors and the two considered error sources, refractivity and deformation. The relationship between the errors and deformation is stronger than that with refractivity. Although the relationship in the experiment does not meet the expectation built from the derived mathematical description, the work has constructed a reasonable theoretical relationship and conducted a preliminary attempt to fit the relationship in reality. | en_US |