【作者】 程滔；

【导师】 单新建；

【作者基本信息】 中国地震局地质研究所 ， 构造地质学， 2007， 硕士

【摘要】 常规InSAR技术在应用中存在一些局限性，主要表现在：时间去相干和空间去相干因素会导致SAR图像对同名像素之间相干性大幅降低，使得干涉与相位解缠等处理难以进行；地表植被、松散地物等对雷达波的后向散射特性随时间变化显著，使得这些地区相隔一个或多个重访周期所获取的SAR图像对同名像素之间相干性很差，甚至不相干，以致在这些地区无法利用InSAR技术进行地表形变监测；另外，大气扰动因素会造成雷达信号延迟和传播路径弯曲，导致获取的相位信息存在较大的误差，且众多的误差源也会影响相位测量的质量，从而降低了InSAR监测结果的精度和可信度。受这些因素的影响，在应用InSAR技术的时候，我们往往需要从一大批SAR数据中挑选相干性好的图像对进行干涉处理，这样的处理使得数据利用率较低。欲充分利用数据，就需对卫星传感器特性、卫星重访周期、卫星重访轨道之间的空间基线距等参数提出严格要求，而这些严格的要求在很多情况下难以满足，这就限制了InSAR技术更广泛的应用。为了解决这些问题，国内外学者已经在探索一些新型的技术，其中具有代表性的有意大利Tele-Rilevamento Europa公司的A．Ferretti等人在2001年提出的PSInSAR(Permanent Scatterer InSAR，永久散射体InSAR)算法理论，和德国波茨坦地质中心的Xia Y．等人在2002年提出的CRInSAR(Corner Reflector InSAR，人工角反射器InSAR)算法理论。这些算法能够有效地解决在低相干区实现InSAR技术监测地表形变的问题，克服了常规InSAR技术的局限性，从而拓宽了InSAR技术的应用领域。虽然，CRInSAR和PSInSAR技术在很大程度上提高了SAR数据利用率，提高了InSAR监测结果的精度；但作者在应用研究中发现，CRInSAR和PSInSAR算法之间具有较强的兼容性和互补性，如果将它们联合起来，则比单一的技术具有更强的优势。因此，本文提出了CR、PS干涉形变测量联合解算算法，并着重论证该算法是否能够有效地提高InSAR形变监测精度。本文的研究就是在这样的背景下展开，在得到国家自然科学基金项目：基于人工和永久角反射器的InSAR微量形变监测模型研究及初步应用(40574007)，与横向课题(与中石油勘探开发研究院合作项目)：利用D-InSAR和CRInSAR技术对西气东输管道工程靖边-临汾段子长县地区滑坡进行监测研究，两个项目的资助下，结合前人研究的基础，从理论和方法的角度进行了一些探索性研究，并提出了一些问题的解决方法。全文共分六章，具体内容包括：第一章引言部分，重点介绍CRInSAR、PSInSAR技术目前发展的基本情况，提出本文拟解决的科学问题。首先，分析常规InSAR技术存在的局限性，引入人工角反射器与永久散射体的基本概念，比较它们与普通地物对雷达信号散射特性的区别，并分析相干性与InSAR提取DEM精度的定量关系；接着，介绍CRInSAR、PSInSAR的技术特点及国内外研究现状，通过对CRInSAR、PSInSAR技术与常规InSAR技术的比较，明确CRInSAR、PSInSAR技术的优势，同时也分析了它们各自存在的缺陷；在此基础上，提出本文要解决的科学问题及研究意义，和本文的研究内容与研究方法。第二章重点论述CR、PS干涉形变测量联合解算算法理论，这是本文的核心部分。首先，详细介绍常规InSAR技术的理论基础与数据处理方法；接着，深入论述CR、PS干涉形变测量联合解算算法，包括联合解算技术前提、理论基础与数据处理方法。在论述过程中，重点介绍了干涉相位与差分干涉相位的组成部分及求取方法，PS点的选取原则与选取标准，以及数据处理流程中极为关键的相位解缠技术，并比较了与常规InSAR在解缠方法与解缠精度方面的差异。第三章重点讲述研究区CR布设与PS选取工作。首先，通过野外调查和光学遥感影像解译，明确研究区的地质构造背景与地质灾害情况，分析研究区现今发生形变事件的动力因素，从而选定重点监测区；接着，基于前期课题中对人工角反射器的研究工作，对人工角反射器进行了改进设计、制作加工和野外架设；然后，接收研究区SAR数据，并对数据进行初步处理，依据处理结果，完成了永久散射体点的选取。第四章重点讲述CR影像特征分析与布设参数校正。布设参数的校正在整个研究工作中是比较重要的环节，首先，从研究区SAR数据中提取CR点的影像特征信息；然后，分析CR点影像特征与卫星过境当地入射角、地球曲率等参数之间的关系，在此基础上，提出CR在布设过程中方位角、仰角的校正方法；并对校正方法进行了编程实现，为今后人工角反射器的架设提供便利和参考。第五章重点讲述CR、PS干涉形变测量联合解算算法数据处理工作，这是算法验证必不可少的部分。首先，对研究区接收的所有SAR数据进行干涉处理分析；然后，根据架设CR的时间，对接收的10景SAR数据分为三个阶段进行了处理，包括对7景架设CR之前数据的常规InSAR处理、对3景架设CR之后数据的联合解算处理、和使用接收的所有10景数据，对整幅图像的左上角区域进行的联合解算处理；通过这些处理，获取了所选区域内相干性值高于所取阀值的所有PS点的形变信息，包括形变速度、DEM误差等，从而验证了联合解算算法的可行性；接着，对数据处理结果进行了精度评定，证明了该算法的高精度特点，并与GPS测量、水准测量进行了比较；最后，分析了InSAR技术在工程应用中的前景。第六章结论。通过对CR、PS干涉形变测量联合解算算法的研究，明确了本文的新意主要表现在以下几个方面：1)提出了CR、PS干涉形变测量联合解算算法，并对算法进行了验证与初步应用；2)提出了基于相干性值与振幅值两个约束条件的永久散射体点选取原则与选取标准，并完成了永久散射体点的选取；3)提出了人工角反射器布设参数的校正方法。本章还分析了论文存在的问题与不足之处，并提出了解决这些问题的方法，希望在今后的研究工作中能够完成。更多还原

【Abstract】 Conventional InSAR (SAR Interferometry) technology has some limitations in application. For example, temporal decorrelation and spatial decorrelation can seriously weaken the coherence between the same pixels in a pair of SAR (Synthetic Aperture Radar) images, which makes the processing of interferometry and phase unwrapping be very difficult. Besides, the RCS (Radar Cross Section) of vegetative cover and loose terra changes evidently with time, which would cause the coherence between the same pixels apart of one or several periods to be very bad even not correlate, and InSAR will take no effect on monitoring the surface deformation in these areas. Additionally, atmospheric disturbance can delay the RADAR signal and curve the transmitting path, which will bring errors to phase composition, and any other errors can also influence the quality of phase calculation. All of these can lower the precision and reliability of InSAR results.Due to these factors, it always needs to choose higher coherence image pairs from a mass of SAR data for interferometry processing. In this case, the utilization ratio of SAR data is very low. It must have strict requirements on the parameters of satellite’s sensor character, repeat period and spatial baseline of repeat orbit and so on. But it’s usually difficult to satisfy these conditions, so it restricts the application fields, and InSAR can not be used more widely.In order to resolve these problems, many researchers (both domestic and foreign) have been developing new technology. In these technology, the PSInSAR (Permanent Scatterer InSAR) proposed in 2001 by A. Ferretti from the company of Tele-Rilevamento Europa and the CRInSAR (Corner Reflector InSAR) proposed in 2002 by Xia Y. from GeoForschungsZentrum Potsdam Germany are more typical. These algorithms conquer the limitations of conventional InSAR and make InSAR can be applied to monitoring of surface deformation in lower-coherence areas, which broadens the application fields of InSAR technology. Although CRInSAR and PSInSAR can improve the utilization ratio of SAR data and the precision of the results effectively, the author finds that CRInSAR and PSInSAR have strong compatibility and can compensate each other very well. If combining them, it will have more advantages. So, this work proposes an algorithm for CR and PS D-InSAR joint calculation, and demonstrates whether this algorithm can effectively improve the precision of InSAR results.Under such a background, and supported by the State Natural Scientific Foundation of China: Research and Preliminary Application of Small Deformation Monitoring Based on CR and PS InSAR (40574007), and the research project (Cooperate with Exploration and Production Research Institute, Sinope): Monitoring Landslides’ Deformation in The County of Zichang in Shanxi Province where the pipeline passes by D-InSAR and CRInSAR, some groping research on theory and methods have been made. Based on the previous research, I propose some methods to deal with problems.The thesis consists of six Chapters, including:Chapter one is the introduction, focuses on the basis of CRInSAR and PSInSAR, and proposes the problems to resolve. The beginning of Chapter one analyzes the limitations of conventional InSAR technology, and introduces the concepts of corner reflector and permanent scatterer, compares their RCS with common earth targets. Here the relationship between coherence and the DEM precision of InSAR is also analyzed. Then, it introduces the characteristics and research development of CRInSAR and PSInSAR. By comparing them with conventional InSAR, the advantages of them are clearly presented. It also analyzes their demerits. On the basis of these analyses, it proposes the problems and significance, and puts forward the research contents and method.Chapter two presents the theory of the algorithm for CR and PS D-InSAR joint calculation, this is the core of the thesis. Firstly, it introduces the theory and data processing methods of conventional InSAR particularly. Then, it discusses the algorithm for CR and PS D-InSAR joint calculation, including the technical precondition, theory foundation and data processing flow. In the discussion, it specially introduces the composition and calculation method of interferometric and differential interferometric phase, PS selection principle and standard, also the key technology about phase unwrapping, and compares it with conventional InSAR in the method and accuracy.Chapter three deals with the tasks about corner reflector installation and permanent scatterer selection. Firstly, by investigation in the field and optical remote sensing interpretation, it clarifies the geological structure background and geological calamity situation of the study area, and analyzes the dynamical factors of the movement, thereby the key monitoring area is chosen. Then, based on the previous research accumulation, the corner reflectors are improved, designed, made and installed in the study area. Then, the SAR data are obtained and processed preliminarily. According to the results, permanent scatterers are selected.Chapter four presents the analysis of corner reflectors’ image characters and the correction method of parameters in comer reflector installation. This part is very important in the whole research. Firstly, it obtains the character information of corner reflectors in the SAR data. Then, on the basis of analysis the relationship between corner reflectors’ image characters and satellite incidence angle, earth’s curvature, it suggests the correction method of corner reflectors’ orientation angle and elevation angle. And finally it programs the method, which could bring convenience and reference to the persons who will install comer reflectors in the future.Chapter five states the data processing by the algorithm for CR and PS D-InSAR joint calculation. This part is necessary to the algorithm validation. Firstly, it carries out InSAR analysis to all of the data obtained. Then, it processes the 10 scenes of SAR data in three stages according to the time when installing CRs, including the conventional InSAR processing of the 7 scenes of data which were obtained before CRs installation. The joint calculation is made for the 3 scenes of data which were obtained after CRs installation, and the processing of the top-left corner in the image with the joint calculation algorithm using all of the 10 scenes of data. By these processing, it gets the deformation velocity and DEM error of all the PSs whose coherence are above the threshold specified. Thereby, it validates the feasibility of the algorithm about the joint calculation. Then, it assesses the precision of these results, and proves the algorithm’s character of high precision. Also, it compares the algorithm with GPS and optical leveling. Finally, it analyzes the prospect of InSAR application in engineering projects.Chapter six is the conclusion. By researching the algorithm for CR and PS D-InSAR joint calculation, the innovations are clearly presented, which include: 1) Proposes the algorithm for CR and PS D-InSAR joint calculation, and carries out validating and preliminary application of it; 2) Proposes the method of permanent scatterer selection based on two principles which are coherence and amplitude, and accomplishes the PS Selection; 3) Proposes the correction method of parameters in corner reflector installation. This chapter also analyzes the problems and shortages in this work, and suggests the treatment method, expects these problems can be solved in the future.更多还原