Surface Displacement Measurement from Remote Sensing Images

3SAR Offset Tracking

Silvan LEINSS^1,2 , Shiyi LI¹, Yajing YAN² and Bas ALTENA³

¹Institute of Environmental Engineering, ETH Zurich, Switzerland

²LISTIC, Savoie Mont Blanc University, Annecy, France

³IMAU, Utrecht University, The Netherlands

In order to provide the basics for the different image correlation methods used for SAR offset tracking, we start with a brief introduction to the SAR imaging geometry and the imaging method and provide a description of radar speckle. Then, we explain various methods of SAR image correlation, followed by two advanced methods using SAR image time series to make offset tracking more robust against decorrelation. We conclude this chapter with the fusion of displacement observations from different orbits into three-dimensional displacement maps.

3.1. Basics of SAR imaging

3.1.1. Imaging geometry and resolution of SAR systems

Synthetic aperture radar (SAR) systems illuminate the scene sideways with a broad antenna beam and sample the backscattered signal at different slant-range distances R (Figure 3.1). The measurement is repeated at different positions along the flight direction (satellite orbit), defining the second image dimension, named the azimuth. Except for interferometric systems, radar systems cannot measure the exact direction (look angle θ) at which the scene is observed. Complementary to radar systems, optical systems can only measure the direction in which radiation is emitted and, except for lidar systems, distances cannot be ...