Multi-baseline interferometric synthetic aperture radar applications and error analysis

Abstract

In this thesis, we deal primarily with the multi-baseline SAR configuration utilizing three satellites. Two applications of InSAR, multi-baseline height retrieval and multi-baseline compensation of CCD's slope biasing effects, are first examined in details. An optimal baseline-weighted height averaging technique is introduced. Phase averaging, a novel height retrieval technique, combines the multi-baseline phase data into one, such that only one set of heights is retrieved from the three-satellite configuration. This approach outperforms single baseline height retrieval and allows application of the conventional two-satellite height retrieval process on the multi-baseline data, without need for excessive modifications. Slope biasing effects, inherent in multilook coherence estimator, make it difficult to identify if low or medium coherence values are results of an actual scene change or an undulating terrain. This ambiguity can be best resolved by accounting for the topographic phase variations via prior knowledge of the original height profile, whose precise retrieval requires a multi-baseline satellite configuration. The three-satellite setup is then related to a realistic cartwheel configuration, where the resulting errors in the height retrieval and CCD process, due to the constant cartwheel rotation, are analyzed. It is found that baseline-weighted averaging becomes a necessary step for the correct and automated retrieval of heights while change detection works equally well when considering a realistic cartwheel setup, even though its performance becomes dependent on the cartwheel's start position. Lastly, errors in satellite positions are introduced and their impacts on height retrieval and CCD are studied.

(cont.) In CCD, it is shown that the effects of satellite position errors is minimal since in this case, only the local terrain profile rather than the absolute terrain matters. However, in height retrieval, small errors in the positions propagate into unacceptably large misalignments. Attempts to account for these errors without prior knowledge of any ground truths are also made, making use of cost minimization functions.