Nowadays, spatiotemporal information, positioning, and navigation services have become critical components of new infrastructure. Precise positioning technology is indispensable for determining spatiotemporal information and providing navigation services. It plays an irreplaceable role not only in scientific research, such as global climate change and earthquake monitoring, but also in the execution of major initiatives like satellite navigation, manned spaceflight, deep space exploration, and in economic development. Moreover, geoinformation science is a discipline that studies the theories and methods for acquiring, managing, querying, analyzing, sharing, utilizing, and visualizing spatiotemporal information. It serves as a key technology for information construction, such as digital earth and smart cities, thus becoming a fast-growing, cutting-edge interdisciplinary field. Both these fields have broad application prospects.
As human activities extend from the Earth's surface to deep space, deep earth, and deep sea at an unprecedented speed and scale, higher demands for the accuracy of the Terrestrial Reference Frame (TRF) and satellite positioning have been raised. For example, establishing a unified reference frame for the Earth and its adjacent space requires precise satellite orbit determination with an accuracy of one centimeter (cm), while monitoring the Earth system, for example, earthquakes and long-term sea-level changes, demands millimeter-level positioning accuracy, with the accuracy of TRF reaching one millimeter (mm). Nevertheless, the latest version of the most widely used international TRF (ITRF) with the highest-precision, ITRF2020, only exhibits an accuracy of 1 cm, which cannot meet these demands. The complex nonlinear motion of globally distributed reference stations used for establishing TRF remains a major factor limiting its accuracy. Among these factors, environmental loads caused by the redistribution of atmospheric, hydrological, and oceanic mass are the primary geophysical origins. Zhao Li and Weiping Jiang from Wuhan University, along with Tonie van Dam from the University of Utah, summarize the recent advances in applying environmental loading to address nonlinear motion in global and regional satellite navigation reference stations, provide an in-depth analysis of the scientific questions of existing studies and insights into future research directions, indicating that further refining the environmental load modeling method, establishing a surface mass distribution model with high spatiotemporal resolution and reliability, exploring other environmental load factors such as ice sheet and artificial mass-change effects, and developing an optimal data-processing model and strategy for reprocessing global reference station data consistently could contribute to achieving the century goal of establishing an "one millimeter-level TRF" in the international geodesy community.
Since 2023, the world has experienced numerous earthquakes. The frequent seismic activities draw the special attention of humankind. Precise coseismic displacements are crucial for earthquake early warning in order to enable decision-makers to issue alerts for public safety. Real-time Global Navigation Satellite Systems (GNSSs) have proven to be a valuable tool for seismic monitoring. Jianghui Geng et al. from Wuhan University have developed the GSeisRT software to support multi-GNSS precise point positioning with ambiguity resolution, achieving real-time positioning with centimeter- to sub-centimeter-level precision. Within a few minutes, the precision of horizontal displacement could reach 4 mm. Since 2019, GSeisRT has been deployed in China, the United States, Chile, New Zealand, and Indonesia, capturing the M7.4 (M stands for magnitude) event in Mexico, the M5.8 event in California (USA), and the M7.3 event in China, which opens up a new approach to wide-area real-time seismic monitoring in real time.
Hyperspectral imaging has significant advantages in precise classification and identification of terrestrial features, thus it is also an important cutting-edge technology for acquiring geographic information. Over the past four decades, the development of hyperspectral remote sensing technology has revolutionized the scope, scale, content, and methods of geoscience research. Despite the high sensitivity of push-broom hyperspectral imagers, they suffer from limited swath and wavelength coverage. Jianxin Jia et al. from the Chinese Academy of Sciences and Finnish Geospatial Research Institute have innovatively designed an airborne multimodular imaging spectrometer (AMMIS) that aims at achieving high spatial resolution, high spectral resolution, wide spectral coverage range, and large field-of-view imaging. AMMIS includes advancements in high-quality spectral spectrometry methods, compact optical design, and integrated layout. At present, AMMIS has been widely used in various fields such as ecological environment monitoring, mineral resource investigation, and land planning, laying a solid foundation for the design of the next generation airborne and spaceborne hyperspectral payloads.
Space-based microwave remote sensing is an important technology for acquiring geographic information about the Earth's surface, including forests, water vapor, soil moisture, and crustal deformation. The frequent occurrence of ionospheric irregularities and scintillation phenomena in equatorial regions would adversely affect these measurements, but provide an alternative new way for probing ionosphere scintillation. Yifei Ji et al. from the National University of Defense Technology have developed a new technology that utilizes L-band synthetic aperture radar (SAR) to detect ionospheric irregularity scintillation effects. This technology achieves an azimuth resolution of better than 100 m and a range resolution of better than one kilometer, demonstrating significant potential for revealing the temporal and spatial distribution characteristics and patterns of equatorial ionospheric irregularities. Ionospheric scintillation is also one of the significant error sources affecting high-precision satellite positioning. Under severe cases, it can lead to signal loss and interruption in receivers, making it impossible to provide positioning information. This new achievement is expected to greatly enhance satellite navigation positioning accuracy in areas prone to strong scintillation.
Urban planning represents a vital application area within geoinformation science. The effective arrangement and intensive utilization of urban buildings are crucial for increasing urban spatial capacity and addressing conflicts over land resources. Over the past few decades, rapid urbanization has led to a transformation in urban development from low-density two-dimensional (2D) sprawl to three-dimensional (3D) expansion. However, current measurements and studies of urban building space are primarily based on a horizontal 2D perspective. Xiaoping Liu et al. from Sun Yat-Sen University, in collaboration with Guangzhao Chen from The University of Hong Kong, have developed the first multi-factor dataset of 3D building space at a 500 m spatial resolution, named GUS-3D. The dataset finely characterizes the gradual decrease in 3D buildings from the city center to the outer edges across different global cities, confirming the dominant role of vertical expansion in 3D urban growth after 2000. It also highlights significant disparities in the supply and inequality of per capita 3D building space among global cities, with regions like India and South Africa providing only one-fourth of the global average, and the distribution being severely uneven. GUS-3D shows great potential to provide reliable foundational data for expanding various urban-related studies into a 3D perspective.
Our world serves as a vast information source. Precise positioning and geoinformation science have been extensively applied, while innovations in the geographic information industry—such as satellite navigation, electronic maps, and remote sensing imagery—are making remarkable advancements, profoundly changing people's lives and work. This special issue has published one review paper and four research papers that address key issues in fields such as high-precision satellite positioning, earthquake monitoring, microwave remote sensing, hyperspectral remote sensing, and urban planning. These works serve as a good starting point for readers to explore methods for further improving satellite navigation precision, conducting real-time monitoring of geological disasters like earthquakes, obtaining accurate geographic information, and promoting sustainable urban development. Since technology shapes the future, we believe that with the ongoing efforts of numerous researchers, greater prosperity and wider application prospects will be achieved in the fields of precise positioning and geoinformation science.
Finally, we would like to express our sincere gratitude to the reviewers for their timely and professional comments during the publication process of this special issue. Your expert insights have ensured its high quality. We also wish to sincerely thank all authors of this special issue from countries including China, the United States, Finland, Chile, Indonesia, Luxembourg, and New Zealand. Your submissions have greatly contributed to the success of this special issue. Additionally, we extend our sincere appreciation to all editors and working staff of the journal. Your dedication has been vital to the achievement of this special issue.
Cite this article: Jiancheng Li, Weiping Jiang, Geospatial Information Technology Innovations: From Earth Monitoring to Urban Planning, Engineering, Volume 47, 2025, Pages 1-2, https://doi.org/10.1016/j.eng.2024.11.002 .
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