Abstract
Although ground-based synthetic aperture radar (GB-SAR) interferometry has a very high precision with respect to deformation monitoring, it is difficult to match the fan-shaped grid coordinates with the local topography in the geographical space because of the slant range projection imaging mode of the radar. To accurately identify the deformation target and its position, high-accuracy geocoding of the GB-SAR images must be performed to transform them from the two-dimensional plane coordinate system to the three-dimensional (3D) local coordinate system. To overcome difficulties of traditional methods with respect to the selection of control points in GB-SAR images in a complex scattering environment, a high-resolution digital surface model obtained by unmanned aerial vehicle (UAV) aerial photogrammetry was used to establish a high-accuracy GB-SAR coordinate transformation model. An accurate GB-SAR image geocoding method based on solution space search was proposed. Based on this method, three modules are used for geocoding: framework for the unification of coordinate elements, transformation model, and solution space search of the minimum Euclidean distance. By applying this method to the Laoguanjingtai landslide monitoring experiment on Hailuogou Glacier, a subpixel geocoding accuracy was realized. The effectiveness and accuracy of the proposed method were verified by contrastive analysis and error assessment. The method proposed in this study can be applied for accurate 3D interpretation and analysis of the spatiotemporal characteristic in GB-SAR deformation monitoring and should be popularized.
Highlights
The high-resolution digital surface model (DSM) obtained by unmanned aerial vehicle (UAV) aerial photogrammetry was used to establish a high-accuracy coordinate transformation model of ground-based synthetic aperture radar (GB-SAR)
High-accuracy geocoding method for GB-SAR based on searching the solution space was proposed, and the coordinate conversion of radar image from 2D plane coordinate system to the local 3D coordinate system was realized. By applying this method to LGJT landslide monitoring experiment on Hailuogou Glacier, the effectiveness was verified by contrastive interpretation and the logical accuracy and accuracy indicators were assessed by quantitative analysis
Based on the geocoding method proposed in this paper, the GB-SAR monitoring system can accurately monitor and interpret the movement of landslides, providing important data and decision support for the monitoring and early warning of high-risk landslides and related geological disasters
Summary
Ground-based synthetic aperture radar (GB-SAR) interferometry is an active microwave remote sensing technology that was developed in the past two decades. GB-SAR interferometry can be used to image the radiation field of radar antenna with high spatiotemporal resolution, yielding single look complex (SLC) images of the target area in the two-dimensional (2D) plane radar coordinate system [1,2]. The emergence of GB-SAR interferometry technology is an important complementarity with spaceborne or airborne interferometric SAR (InSAR) technology, which greatly promotes the application of InSAR technology in the field of deformation monitoring [3]. Owing to the satellite revisit period and side looking angle of the sensor, monitoring with high spatiotemporal resolution
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