This book contains a selection of peer-reviewed papers presented at the VIII Hotine-Marussi Symposium on Mathematical Geodesy in Rome, 17-21 June, 2013. The scientific sessions focused on global reference systems, geodetic data analysis, geopotential modelling, gravity field mapping as well as digital terrain modelling. A special chapter is dedicated to understand the generation of Flash.

This open access book contains 30 peer-reviewed papers based on presentations at the 27th General Assembly of the International Union of Geodesy and Geophysics (IUGG). The meeting was held from July 8 to 18, 2019 in Montreal, Canada, with the theme being the celebration of the centennial of the establishment of the IUGG. The centennial was also a good opportunity to look forward to the next century, as reflected in the title of this volume. The papers in this volume represent a cross-section of present activity in geodesy, and highlight the future directions in the field as we begin the second century of the IUGG. During the meeting, the International Association of Geodesy (IAG) organized one Union Symposium, 6 IAG Symposia, 7 Joint Symposia with other associations, and 20 business meetings. In addition, IAG co-sponsored 8 Union Symposia and 15 Joint Symposia. In total, 3952 participants registered, 437 of them with IAG priority. In total, there were 234 symposia and 18 Workshops with 4580 presentations, of which 469 were in IAG-associated symposia.

The Hotine-Marussi Symposium is the core meeting of a “think thank”, a group scientists in the geodetic environment working on theoretical and methodological subjects, while maintaining the foundations of geodesy to the proper level by corresponding to the strong advancements improved by technological development in the field of ICT, electronic computing, space technology, new measurement devices etc. The proceedings of the symposium cover a broad area of arguments which integrate the foundations of geodesy as a science. The common feature of the papers therefore is not on the object, but rather in the high mathematical standards with which subjects are treated.

This open access volume contains selected papers of the 2021 Scientific Assembly of the International Association of Geodesy – IAG2021. The Assembly was hosted by the Chinese Society for Geodesy, Photogrammetry and Cartography (CSGPC) in Beijing, China from June 28 to July 2, 2021. It was a hybrid conference with in-person and online attendants. In total, the Assembly was attended by 146 in-person participants and 1,123 online participants. The theme of the Assembly was Geodesy for a Sustainable Earth. 613 contributions (255 oral presentations and 358 poster presentations) covered all topics of the broad spectrum considered by the IAG: geodetic reference frames, Earth gravity field modelling, Earth rotation and geodynamics, positioning and applications, the Global Geodetic Observing System (GGOS), geodesy for climate research, marine geodesy, and novel sensors and quantum technology for geodesy. All published papers were peer-reviewed, and we warmly recognize the contributions and support of the Associate Editors and Reviewers.

This open access volume contains the proceedings of the 5th Symposium on Terrestrial Gravimetry: Static and Mobile Measurements (TG-SMM2019) held in St. Petersburg, Russia, October 1 – 4, 2019. The symposium was hosted by the State Research Center of the Russian Federation Concern CSRI Elektropribor, JSC and was attended by 75 participants from 15 different countries. 32 oral and 20 poster contributions were presented in four different topical sessions: Terrestrial, shipboard and airborne gravimetry, Absolute gravimetry, Relative gravimetry, gravity networks and applications of gravimetry and Cold atom and superconducting gravimeters, gravitational experiments.