Editorial for the Special Issue on Geodesy and Survey Engineering
Jiancheng Li · Engineering · 2020
Geodesy is the science of accurately measuring, determining, and monitoring three fundamental properties of the Earth: its geometry, its gravity field, and its orientation in space-as well as the evolution of these properties over time.Geodesists also study corresponding topics for other planets in the solar system.Traditionally, the understanding of geodesy has led to the definition of three pillars of this field: ① geokinematics, ② Earth rotation, and ③ gravity field.As they are intrinsically linked to each other, these three pillars jointly change as a consequence of dynamic processes in the Earth system.Geodesy is now not only a fundamental subject of the geosciences, but also widely used in engineering construction.With the advent of new space-geodetic techniques (e.g., the global navigation satellite system (GNSS), satellite laser ranging (SLR), low-Earth orbit (LEO) satellites, interferometric synthetic aperture radar (InSAR), very-long-baseline interferometry (VLBI), etc.), together with the rapid improvement of communication techniques and capacities, remarkable advances in recent years have evidenced that geodesy is undergoing fundamental changes in theory, method, engineering, technology, observation, and practiceoriented services.Nowadays, geodesy is facing increasing demands from scientists, the Earth-observation community, and society at large for improved services, observations, and products.In particular, new geodetic technologies allow us to observe changes in the Earth's shape, rotation, and gravity field with increasing spatial and temporal resolution, higher accuracy, and lower latency.Hence, geodesy today is crucial not only for Earth-observation science, but also for supporting many processes in modern society.Examples include applications in process control (e.g., farming, construction, mining), navigation and transport, infrastructure construction and monitoring (e.g., off-shore platforms, bridges, and other large civil structures), monitoring and early warning of geohazards and anthropogenic hazards, and so forth.As the key space-geodetic technique, GNSS provides unprecedented potential for precise ground-and space-based positioning and navigation anywhere in the world with centimeter-level accuracy.In this special issue, several articles report on recent progress