A Study Of InSAR Application Technology Based On The Point Target Detection And Analysis

Spaceborne synthetic aperture radar interferometry (InSAR) is a new remote sensing technology which can obtain large areas of information on surface topography and deformation all-time and all-weather. The terrain in central and western China is too complex to get involved for humans, so it's difficult to do any artificial ground-based measurements.In eastern China, the industrial and agricultural is well developed, human activities lead to frequent disasters of all kinds of surface deformation. The cost of long-term monitoring of artificial is high and its spatial resolution is low. So the conventional measurements are limited by the ground-work area, climate conditions and costs while InSAR technology has great advantages. However, in the practical application of InSAR technology, it is often difficult to achieve the theoretical accuracy for some factors:changes in the physical property of surface scatters over time lead to decoherence; baseline error leads to geometric decoherence; the effect of atmospheric phase screen leads to interferometry measurement error.The other factors include orbit errors, topography error, system thermal noise and so on. These factors have limited the specific application of InSAR technology.In this paper, we study the InSAR technology for obtaining the information of surface topography and the timing deformation with the extraction and analysis of the point targets. In the study of the extraction of surface topography, to improve the accuracy of digital elevation model(DEM) obtained by InSAR technology, we estimate the coherence map of the interferogram to extract high-coherence point targets and establish multiple linear regression model with external DEM data to reduce InSAR phase errors caused by the spatial correlated effects of atmospheric phase screen (APS) and baseline error. In the study of the extraction of the timing surface deformation, we use the external atmospheric data to obtain the regional atmospheric phase delay field between different SAR observation times to study the APS effect on InSAR phase. To avoid errors from decoherence areas, the phase stable point targets(high coherence and high SNR) are extracted in mathematical and physical sense from SAR data sets in long time series. Firstly we use an adaptivea gradient filter method based on wavelet transformation to improve signal to noise ratio of interferogram data sets. Secondly the amplitude dispersion index is used to select the candidate persistent scatterers(PSC) quickly. Then several factors such as negative correlation coefficient, SNR and probability analysis factor are used to do the selection of PSs from PSC. Finally the interferograms are unwrapped and spatial-temperal filtered to extract the surface deformation. We set this process to establish an interferometric phase mode and utilize the spatial-temperal model to do the quantitative analysis by leaning from Stanford method for persistent scatterers(StaMPS). In the study area, surface deformation of sub-centimeter accuracy and the overall situation are obtained by the result of experiments. We also analyze the surface deformation susceptibility in the study area based on several factors such as geology, hydrogeology, human activities and so on.