以統計同質分布散射體干涉雷達技術偵測地表變形

Surface Deformation Detected by a Radar Interferometric Technique Using Statistically-Homogeneous Distributed Scatterers

黃郁棠(Yu-Tang Huang) ； 張奇(Chi Chang) ； 吳究(Joz Wu) ； 蔡長興(Chang-Xing Tsai)

《航測及遙測學刊》 19卷3期 (2015/01) Pp. 239-251

https://doi.org/10.6574/JPRS.2015.19(3).6

摘要

合成孔徑雷達干涉技術不受日夜及天候限制的條件，至今仍是光學影像無法取代的優點。而衍生的干涉雷達技術能建置數值地形模型，亦或是量測地表變形等，近年來也被廣泛的研究。干涉雷達技術主要係藉發出的微波經目標反射後，由兩個不同位置的接收器收到回波訊號的相位差，來獲取地表三維資訊。如利用多時期的影像重複此方法後所得到的三維資訊做比較，最後可獲得地表變形速率的資訊。而長時間觀測中，因多時期影像同調性較低，故須找出訊號穩定的永久散射體加入計算，藉其回波穩定的特性來提升其量測的精度。但台灣地區地貌變化快速，使得永久散射體在山地、叢林等區域密度過低，使得永久散射體干涉雷達技術效果不甚理想。故本研究主要是在探討合成孔徑雷達干涉技術用於臺灣地區量測地表變形所遭遇的問題與改善方法。原先永久散射體數量不夠導致密度不足的部份，加入了分布散射體來提升，密度由每平方公里0.3個點提昇至4.6個點。分布散射體是經由統計及空間適應性濾波處理後的影像，其回波一致對應的像素，和永久散射體原理上為不同概念，但其有一定的可靠性。最後結合兩者，計算出地表變形速率，改善原先方法上的不足以得到更好的成果。

關鍵字

干涉雷達 ； 永久散射體 ； 分布散射體 ； 地表變形

並列摘要

The technique of the Synthetic Aperture Radar (SAR) is developed in recent years. Without the limit of the weather and sunshine, SAR is different from the optical technique. The extension of the improved SAR technique, such as Interferometry SAR (InSAR) and Persistent Scatterer InSAR (PSInSAR), are widely used to build the Digital Terrain Model (DTM) and detect the deformation rate of the surface. The basic theory of an InSAR technique is based on time difference in arriving at two different receivers from the signal which was just sent out by the transmitter of a satellite. The changes in height can be converted to phase differences. However, if the observed time is extended, the dependence and precision will decrease because of a lowering coherence of two images. This problem may be solved by using the PSInSAR technique. The method is used to find points with stable signatures. According to the characteristics of these points, the result usually has high precision, which is mentioned in many research papers. If this method is applied to SAR images of Taiwan areas, it is not so satisfactory because the surface deformation is too erratic. So, our research aims to improve this method to make it appropriate for the country. To do this, additional information is needed. We should find other points called the distributed scatterer. Distributed scatterers are selected by the center pixel of a region which has the same signal reflection. They have excellent dependence on account of statistical calculations. As distributed scatterers are included, the improved effect is shown in our research.

並列關鍵字

Interferometric SAR ； Persistent scatterer ； Distributed scatterer ； Surface deformation