Kenyeres A.,FOMI Satellite Geodetic Observatory |
Sacher M.,Federal Agency for Geodesy and Cartography |
Ihde J.,Federal Agency for Cartography and Geodesy BKG |
Denker H.,Leibniz University of Hanover |
Marti U.,Federal Office of Topography
International Association of Geodesy Symposia | Year: 2010
EUREF, the Sub-commission for the Euro-pean Reference Frame within IAG Commission 1, in cooperation with the European Geoid and Gravity Project (EGGP), is developing a homogeneous continental GPS/leveling database. EUVN_DA, the Densification Action of the EUVN (European Unified Vertical Reference Network) project is designed to support the development of the new European geoid solutions and to contribute to the realization of an accurate continental height reference surface. The cm-accuracy GPS/leveling database could also be used for the realization of the European Vertical Reference System (EVRS) and for the analysis of the national height networks. The establishment of the EUVN_DA network was started in 2003. The database now consists of about 1,500 high quality GPS/leveling points contributed from 25 countries. The GPS coordinates refer to the realizations of the ETRS89 and the leveling data to EVRS2007. Most of the EUVN_DA benchmarks are integrated into the UELN (United European Leveling Network) to assure the long term homogeneity and consistency of the height information. The GPS database mostly relies on existing measurements which fulfilled pre-defined quality requirements. The main phase of the project terminates by the end of 2008, but the periodic maintenance of the database is planned on long term. This paper summarizes the activities within the EUVN_DA project, gives an overview on the actual status and presents the results on the analysis of the continental geoid solutions. © Springer-Verlag Berlin Heidelberg 2010.
Olteanu-Raimond A.-M.,French Mapping Institute |
Hart G.,University of Nottingham |
Foody G.M.,University of Nottingham |
Touya G.,French Mapping Institute |
Kellenberger T.,Federal Office of Topography
Transactions in GIS | Year: 2017
The perspective of European National Mapping Agencies (NMA) on the role of citizen sensing in map production was explored. The NMAs varied greatly in their engagement with the community generating volunteered geographic information (VGI) and in their future plans. From an assessment of NMA standard practices, it was evident that much VGI was acquired with a positional accuracy that, while less than that typically acquired by NMAs, actually exceeded the requirements of the nominal data capture scale used by most NMAs. Opportunities for VGI use in map revision and updating were evident, especially for agencies that use a continuous rather than cyclical updating policy. Some NMAs had also developed systems to engage with citizen sensors and examples are discussed. Only rarely was VGI used to collect data on features beyond the standard set used by the NMAs. The potential role of citizen sensing and so its current scale of use by NMAs is limited by a series of concerns, notably relating to issues of data quality, the nature and motivation of the contributors, legal issues, the sustainability of data source, and employment fears of NMA staff. Possible priorities for future research and development are identified to help ensure that the potential of VGI in mapping is realized. © 2016 John Wiley & Sons Ltd
Thovert J.-F.,Institute PPRIME |
Mourzenko V.V.,Institute PPRIME |
Adler P.M.,University Pierre and Marie Curie |
Nussbaum C.,Federal Office of Topography |
Pinettes P.,University of Nimes
Engineering Geology | Year: 2011
This paper deals with the reconstruction of a fracture network observed in an underground gallery of a tunnel buried in clay stones in Switzerland, below Mont Terri. The trace maps of the Gallery 04 and of the EZ-G niche of this site have first been digitized and used in various ways to characterize the data. The traces have been divided into two groups, i.e., the pre-existing faults in the gallery and the fractures of the excavated damaged zone (EDZ) in the niche. Each group has been analyzed individually. The number of data for the faults has turned out to be statistically significant, while it was very limited for the EDZ fractures. For both cases, the major statistical characteristics of the traces have been extracted and a reconstruction procedure developed and tested. A full example has been worked out; a gallery immersed in a reconstructed fractured porous medium has been meshed, and the electrical field created by a dipole at the wall calculated by solving the three dimensional Laplace equations in the fractures and in the porous medium. © 2010 Elsevier B.V.
Meindl M.,ETH Zurich |
Beutler G.,University of Bern |
Thaller D.,Bundesamt fur Kartographie und Geodasie |
Dach R.,University of Bern |
And 2 more authors.
Journal of Geodesy | Year: 2014
Meindl et al. (Adv Space Res 51(7):1047–1064, 2013) showed that the geocenter (Formula presented.)-component estimated from observations of global navigation satellite systems (GNSS) is strongly correlated to a particular parameter of the solar radiation pressure (SRP) model developed by Beutler et al. (Manuscr Geod 19:367–386, 1994). They analyzed the forces caused by SRP and the impact on the satellites’ orbits. The authors achieved their results using perturbation theory and celestial mechanics. Rebischung et al. (J Geod doi:10.1016/j.asr.2012.10.026, 2013) also deal with the geocenter determination with GNSS. The authors carried out a collinearity diagnosis of the associated parameter estimation problem. They conclude “without much exaggerating that current GNSS are insensitive to any component of geocenter motion”. They explain this inability by the high degree of collinearity of the geocenter coordinates mainly with satellite clock corrections. Based on these results and additional experiments, they state that the conclusions drawn by Meindl et al. (Adv Space Res 51(7):1047–1064, 2013) are questionable. We do not agree with these conclusions and present our arguments in this article. In the first part, we review and highlight the main characteristics of the studies performed by Meindl et al. (Adv Space Res 51(7):1047–1064, 2013) to show that the experiments are quite different from those performed by Rebischung et al. (J Geod doi:10.1016/j.asr.2012.10.026, 2013). In the second part, we show that normal equation (NEQ) systems are regular when estimating geocenter coordinates, implying that the covariance matrices associated with the NEQ systems may be used to assess the sensitivity to geocenter coordinates in a standard way. The sensitivity of GNSS to the components of the geocenter is discussed. Finally, we comment on the arguments raised by Rebischung et al. (J Geod doi:10.1016/j.asr.2012.10.026, 2013) against the results of Meindl et al. (Adv Space Res 51(7):1047–1064, 2013). © 2014, Springer-Verlag Berlin Heidelberg.
Arnold D.,University of Bern |
Meindl M.,ETH Zurich |
Beutler G.,University of Bern |
Dach R.,University of Bern |
And 7 more authors.
Journal of Geodesy | Year: 2015
The Empirical CODE Orbit Model (ECOM) of the Center for Orbit Determination in Europe (CODE), which was developed in the early 1990s, is widely used in the International GNSS Service (IGS) community. For a rather long time, spurious spectral lines are known to exist in geophysical parameters, in particular in the Earth Rotation Parameters (ERPs) and in the estimated geocenter coordinates, which could recently be attributed to the ECOM. These effects grew creepingly with the increasing influence of the GLONASS system in recent years in the CODE analysis, which is based on a rigorous combination of GPS and GLONASS since May 2003. In a first step we show that the problems associated with the ECOM are to the largest extent caused by the GLONASS, which was reaching full deployment by the end of 2011. GPS-only, GLONASS-only, and combined GPS/GLONASS solutions using the observations in the years 2009–2011 of a global network of 92 combined GPS/GLONASS receivers were analyzed for this purpose. In a second step we review direct solar radiation pressure (SRP) models for GNSS satellites. We demonstrate that only even-order short-period harmonic perturbations acting along the direction Sun-satellite occur for GPS and GLONASS satellites, and only odd-order perturbations acting along the direction perpendicular to both, the vector Sun-satellite and the spacecraft’s solar panel axis. Based on this insight we assess in the third step the performance of four candidate orbit models for the future ECOM. The geocenter coordinates, the ERP differences w. r. t. the IERS 08 C04 series of ERPs, the misclosures for the midnight epochs of the daily orbital arcs, and scale parameters of Helmert transformations for station coordinates serve as quality criteria. The old and updated ECOM are validated in addition with satellite laser ranging (SLR) observations and by comparing the orbits to those of the IGS and other analysis centers. Based on all tests, we present a new extended ECOM which substantially reduces the spurious signals in the geocenter coordinate $$z$$z (by about a factor of 2–6), reduces the orbit misclosures at the day boundaries by about 10 %, slightly improves the consistency of the estimated ERPs with those of the IERS 08 C04 Earth rotation series, and substantially reduces the systematics in the SLR validation of the GNSS orbits. © 2015, Springer-Verlag Berlin Heidelberg.
News Article | February 15, 2017
Switzerland’s national mapping agency, the Federal Office of Topography swisstopo, has implemented Analytical Graphics, Inc.’s (AGI) 3D Tiles Processing Software to convert 3D geospatial content into 3D Tiles for streaming into the agency’s geoportal, as well as, to fuse the 3D geospatial content on top of the surrounding terrain. swisstopo, which is responsible for geographical reference data for the Swiss Confederation, produces high quality maps of Switzerland and documents geological, geodesic and topographical changes in the landscape. As part of the Geoinformation Act to make Swiss geospatial data available for widespread use, it is implementing Cesium, the WebGL open-source globe, as a way to visualize their cartographically beautiful products in 3D. swisstopo is utilizing AGI’s software to process their extensive data collection into 3D Tiles in order to stream it into their Cesium-based online viewer and to ensure the data appears correctly on top of the terrain. “swisstopo has amassed a truly phenomenal collection of data. They’re world-renowned. We are thrilled to see them implement 3D Tiles, along with other data services into a Cesium globe, showcasing Cesium’s interoperability and range,” said Todd Smith, Cesium Product Manager. “Using the open 3D tiles format for data dissemination allows swisstopo to integrate a scalable 3D Tiles service. This will leverage the usage of 3D data and hence bring the 3D geodata potential to life,”said David Oesch swisstopo Project Lead. The 3D Tiles format, developed by AGI’s Cesium team, is an open specification for streaming massive heterogeneous 3D geospatial datasets including buildings, terrain, imagery, point clouds, and vector data.