Tomographic SAR Reconstruction of a 4D City using TerraSAR-X data

Table of Contents

1 Introduction

1.1 Motivation: The 4th Dimension

1.2 Purpose and Structure

1.3 About TerraSAR-X

1.3.1 TerraSAR-X Scanning Modes

2 Theoretical Basics - SAR Principles

2.1 SAR Geometry

2.2 SAR Phase

2.3 SAR Properties

2.3.1 Layover

2.3.2 Chirp

2.3.3 Speckle

2.4 SAR Image Resolution

2.5 InSAR Basics

2.5.1 Interferometric Phase

2.5.2 InSAR Athmospheric Influences

2.5.3 InSAR Height Retrieval

2.6 Persistent Scatterer Interferometry (PSI)

2.7 SAR Tomography

3 TomoSAR

3.1 TomoSAR Processing Procedures

3.2 Pre-Processing

3.3 Processing

3.3.1 TomoSAR System Model

3.3.2 TomoSAR Algorithm

4 Application on Berlin Data Stack

4.1 Downsampling

4.2 Quality Measurements

4.3 Creating Pixel Pairs

4.4 Integration

4.5 Filter Residual Phase

4.6 Upsamling and Estimation

5 Results and Analysis

5.1 Deformations and Movements

5.1.1 Seasonal Movements

5.1.2 Linear Movements

5.2 Verification and Observation of the processed SAR Data Stack

5.2.1 TomoSAR Result Observation

5.2.2 Virtual Inspection of Observation

5.3 Inspected Targets

5.3.1 ”Uberflieger Br¨ ¨ ucke”

5.3.2 ”Berlin Hauptbahnhof”

6 Conclusion

Objectives & Topics

The primary objective of this bachelor thesis is to utilize Tomographic SAR (TomoSAR) techniques on high-resolution TerraSAR-X satellite data to monitor and analyze 4D ground and infrastructure movements in urban areas, specifically focusing on the city of Berlin.

• Application of advanced TomoSAR processing methods to extract 3D positions and motion parameters.
• Analysis of seasonal and linear movement patterns in urban infrastructure.
• Technical evaluation of TerraSAR-X data and its suitability for high-resolution urban monitoring.
• Integration of SAR-derived point clouds with existing 3D models for ground truth validation.

Excerpt from the Book

Summary of Chapters

1 Introduction: Provides an overview of the motivation for 4D urban modeling, the potential of SAR technology, and the structure of the thesis.

2 Theoretical Basics - SAR Principles: Explains the fundamental physical and mathematical concepts of Synthetic Aperture Radar, including geometry, phase, and interferometry.

3 TomoSAR: Details the Tomographic SAR processing chain, focusing on system models and specific algorithms like SVD-Wiener and SLIMMER.

4 Application on Berlin Data Stack: Describes the practical implementation of the workflow, including downsampling, quality measurement, and spatial filtering using Berlin as the test area.

5 Results and Analysis: Presents the findings regarding deformation and movements, featuring an analysis of the Berlin Hauptbahnhof and the "Uberflieger Brücke".

6 Conclusion: Summarizes the effectiveness of TomoSAR as a tool for urban deformation monitoring and provides final insights on its practical utility.

Keywords

Tomographic SAR, TerraSAR-X, 4D urban modeling, Interferometry, InSAR, PSI, deformation monitoring, infrastructure, Berlin, spotlight data, signal processing, elevation, movement analysis, remote sensing, satellite radar.

Frequently Asked Questions

What is the core focus of this bachelor thesis?

The work explores the application of Tomographic SAR (TomoSAR) for monitoring 4D movement and deformation of urban infrastructure using high-resolution data from the TerraSAR-X satellite.

What are the primary themes discussed in the research?

Key themes include the principles of SAR and Interferometry (InSAR), the development of 4D models, the technical challenges of urban monitoring, and practical deformation analysis of specific structures like bridges and train stations.

What is the main objective or research question?

The objective is to test and validate whether TomoSAR, utilizing VHR spotlight data, can successfully provide accurate, millimeter-level measurements of building and ground movements in an urban setting.

Which scientific methods are applied?

The study employs TomoSAR processing, specifically using SVD-Wiener filtering to handle multiple scatterers within resolution cells, and incorporates spatial difference algorithms to mitigate atmospheric phase screen (APS) effects.

What is covered in the main section of the document?

The main section covers the theoretical foundations of SAR, the processing workflow (downsampling, integration, filtering), and a detailed result analysis focused on the infrastructure in Berlin.

Which keywords best characterize this research?

Essential keywords include Tomographic SAR, TerraSAR-X, 4D modeling, InSAR, deformation monitoring, and urban infrastructure.

How is the "layover" effect addressed in this thesis?

The thesis utilizes TomoSAR, which decomposes the information within a single resolution cell into different elevations, effectively resolving the ambiguities that typically cause the layover effect in standard SAR imaging.

What specific movement patterns were observed in Berlin?

The research identified significant seasonal motion patterns in materials like steel and glass, particularly noticeable at the Berlin Hauptbahnhof and railway bridges, likely caused by thermal expansion.

Why is the SVD-Wiener filter used in the processing?

The SVD-Wiener filter is utilized because it is computationally efficient and provides a robust, linear method for estimating unknown parameters and the true elevation of shifting scatterers.