Interactive Web Mapping Applications for 2D and 3D Geo-Visualization of Persistent Scatterer Interferometry SAR Data

Abstract

Surface motion is a complex, dynamic phenomenon that draws significant scientific attention. This study focuses on the development of a cartographic toolset for the visualization of space-borne Persistent Scatterer Interferometry (PSI) surface motion measurements. The entire archive of Sentinel-1 Synthetic Aperture Radar (SAR) imagery over the broader Thessaloniki (Greece) area has been exploited to derive the PSI measurements utilizing the Surface motioN mAPPING (SNAPPING) service on the Geohazards Exploitation Platform (GEP). A collection of web map applications, interactive visualization tools, and an animated map were developed based on state-of-the-art approaches. This geo-visualization toolset consists of the following: (i) Three web map applications exploring PSI velocity rates, PSI time series, and a comparison of PSI with geodetic leveling data; (ii) Two interactive map tools focusing on 3D visualization of PSI time series and estimating velocity rates for predefined temporal frames; and (iii) An animated map of PSI time series. The utilization of the aforementioned visualization toolset provided useful conclusions about the variety of land displacement that occurs in different subareas of Northern Greece from different causes. More specifically, certain subareas with significant subsidence rates range from −2 mm/year up to −18 mm/year from 2015 to 2020. The magnitude of displacement and the underlying causes (subsidence, faults, landslides, human processes, etc.) varies across different subareas. On the other hand, a subarea of uplift trend exists in the north of the city of Thessaloniki with displacements up to 5 mm/year for the period between 2015–2020, despite being constrained by the fact that the geo-visualization platform is able to display SNAPPING PSI measurements from any location around the world, making it a useful tool for global exploration. The platform’s contents are available through a user-friendly graphical interface and are mostly addressed to domain experts as well as end-users. Opposed to similar approaches where static 2D maps and velocity rates web applications are presented through this platform, users can monitor and study the dynamic behavior of surface motion to a spatiotemporal extent more thoroughly.