APPLICATION OF INSAR TECHNOLOGY IN GEOGRAPHICAL SITUATION MONITORING

In this paper, based on the geographical situation monitoring project of the earthquake zone of ludian county, zhaotong city, yunnan province,using the data of the radarsat-2 satellite( time frame is 20140304-20150416 ), InSAR technology is used to monitor the topography of the earthquake zone(about 420 square kilometers of monitoring area).Through the analysis of topographic deformation results, the scope of the terrain change is obtained, and the application and problems of InSAR technique in topographic geomorphological monitoring are discussed. _______________________________ Corresponding author Wang yuhong The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLII-3, 2018 ISPRS TC III Mid-term Symposium “Developments, Technologies and Applications in Remote Sensing”, 7–10 May, Beijing, China This contribution has been peer-reviewed. https://doi.org/10.5194/isprs-archives-XLII-3-1841-2018 | © Authors 2018. CC BY 4.0 License. 1841


Basic principles of InSAR
This section focuses on the basic principles of

Geocoding:
The resulting phase is in the radar coordinate system (line number, column number, elevation), and it needs to be converted to the right Angle coordinate system (longitude, latitude,elevation) of an ellipsoidal coordinate system,it can be used by us, namely, geo-coding processing.Figure 7 for the deformation diagram after the geocoding.

Analysis of topographic deformation results
The deformation results obtained by the interference of image are shown in figure 8, where the red pentagonal star is the epicenter location and the black curve is the monitoring range, the red curve is the area photography measurement and remote sensing has been effectively complemented, and new observation methods and application fieldshave been developed.InSAR technology not only should surveying and mapping such as topographic mapping and DEM generation, itcan also be applied to thematic mapping such as agriculture and forestry mapping.The monitoring of geographical situation is a major project developed by the country in recent years.The project has been applied to a number of high-tech technologies,suchasGIS,GPS and RS technology.New space observation technology is developed in the late twentieth Century,InSAR technology will be further implemented in national-disaster monitoring projects.Based on the geographical situation monitoring project of the earthquake area of ludian county in zhaotong city, yunnan province, this paper discusses application and encountered problems on the technique of InSAR monitored in the terrain and geomorphology.
Insar.The interference analysis of two SAR images in the same area obtained at different time/location can be understood as the co-conjugate of pixel complex values is multiplied, that is IF(r，a) =M (r，a)• S(r，a) * (1) Here, (r, a) is the pixel slope, azimuth direction coordinates, M, S, respectively, main SAR image and secondary image, and IF is obtained the interferogram (plural).As shown in FIG.1phase principal value of each complex number in the graph is dominated by equation (1), and the phase difference between the images corresponds to the pixel.That is the interference phase.

Figure
Figure 1 Basicprinciple diagram of InSAR

Figure 2
Figure 2 The intensity diagram of the main image (a) and the secondary image (b) (after registration)

Figure 3
Figure 3 Original coherent graph filter: Because the generated InSARinterferogram is caused by geometric overthrust, system thermal noise, time change and local match misalignment,the influence of the incoherent noise and other factors, signal-to-noise ratio of the generated InSARinterferogram is low and needs to be filtered and processed in this paper, the signal-to-noise ratio of the interference graph is improved, and the reliability of the phase solution and the interpretation ability of the interference graph are further improved.Figure 5 shows the following the interferogram (a) and the coherent graph (b) after the complex image filtering.Compared to figure 4 and 5, the coherence value and phase value of the filter are available,there was a marked improvement in readability.

Figure 5
Figure 5 The differential interferogram graph (a) and coherence graph after filtering(b)

Figure 8 Figure 9
Figure 8 Deformation figure