Papers 25,640 records found  previous11 - 20nextend  jump to record: Search took 0.00 seconds. 
Impact of GNSS Signal Interference on Geodetic Measurement
Global Navigation Satellite Systems are based on receiving GNSS signals from Medium Earth Orbit (MEO) satellites around 20 000 km above the Earth. It represents a high susceptibility to interference of these signals. Recently, our users have been contacting us as SKPOS service administrators with problems when measuring near the road infrastructure. Since 2010, vehicles over 3.5 tons have paid electronic tolls in Slovakia according to mileage, which are tracked using GPS. This has caused an increased usage of simple GNSS signal jammers. The author of the article conducted an experiment with the aim to determine the influence of the GNSS signal jammer on geodetic measurements.
Permanent GNSS Networks and Their Use in Geodynamic Monitoring of the Bohemian Massif
Pospíšil, Lubomil ; Švábenský, Otakar
The paper deals with the problematics of permanent GNSS stations and networks in terms of their use for geodynamic research. General aspects and characteristics of the establishment and operation of permanent stations are stated. Some purpose-built geodynamic networks related to important regional projects are described. Finally, attached are two examples of geodynamic research using permanent GNSS networks in the Czech Republic. The first example concerns the survey of indications of horizontal movement tendencies concerning the territory of the Bohemian Massif and its relations to the surrounding structures. The second example concerns a more detailed geological and geodynamic research of the fault systems of the Blanice Graben.
Estimation of Litospheric Elastic Thicknes from In-orbitGOCE-based Vertical Gradients and CRUST1.0
Pitoňák, Martin ; Eshagh, Mehdi ; Šprlák, Michal ; Novák, Pavel
The lithospheric strength with respect to the loading is represented by a parameter called elastic thickness (Te) and places with larger value of Te flex less. In this contribution, we use the in-orbit vertical gravitational gradients measured by Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite for determining the elastic thickness over Africa. A forward computational method is developed based on the Vening Meinesz-Moritz (VMM) and flexural theories of isostasy to find a mathematical relation between the second-order vertical derivative of the gravitational potential and mechanical properties of the lithosphere. This method is developed in terms of spherical harmonics. Loading effects of topography and bathymetry, sediments and crystalline masses are calculated from CRUST1.0, in addition to estimates of laterally-variable density of the upper mantle, Young’s modulus and Poisson’s ratio. The second-order vertical derivatives of the gravitational potential are synthesised from the crustal model and different a priori values of elastic thickness to find which one matches the GOCE in-orbit vertical gradient. Our map of Te over Africa shows that the high values of Te are mainly associated with the cratonic areas of Congo, Chad and the Western African basin while the intra-continental hotspots and volcanoes, such as Ahaggar, Tibesti, Darfur, Cameroon volcanic line and Libya are connected by corridors of low Te.
15 Years of SKPOS Current Status, News, Curiosities
Droščák, Branislav ; Smolík, Karol
Slovak real-time positioning service (SKPOS) celebrated in 2021 its fifteenth anniversary. SKPOS is the most used geodetic controls service and is available to its users 24/7/365 with minimal outages. SKPOS represents with its GNSS permanent stations infrastructure the active geodetic controls of Slovakia and an important part of the National Spatial Network. Geodetic and Cartographic Institute Bratislava, as the service administrator, carries out its constant development and modernization, e.g. recently the SKPOS Online Postprocessing application was the launch. The application allows users to process static measurements online without importance to have their own computation software. Another modernization represents the relocation of several reference stations from the roofs to pillar monumetation collocated with InSAR corner reflector.
Differences Between Heights in the Bpv System and Heights Based on the EGM96 Model
Vaňková, Zuzana
This work deals with determining the differences between heights in the Bpv system and heights based on the geopotential model EGM96. The height difference is calculated as the difference between the geoid undulation and the height anomaly of the quasigeoid, where both quantities are related to the same reference ellipsoid. Part of the work is devoted to determining the undulation of the geoid from a set of Stokes coefficients for the gravitaty field model EGM96. Furthermore, the quasigeoid models CR-2005 and QGZÚ-2013 are used for the needs of this work, which are described by the values of the height anomaly in the regular grid. Another source of data used is a set of selective maintenance points.
Austfonna Glacier Ice Sheet Variation Monitoring Using GRACE and GRACE-FO Data
Korekáčová, Barbora
GRACE and GRACE-FO satellite missions provide important data necessary for temporal gravity field variation modelling. The main cause of Earth’s gravity field variations monitored by GRACE and GRACE-FO is the motion of Earth masses. To assess the ice mass variations, we have to correct the measured gravity signal for land hydrology variations and effect of post-glacial isostatic rebound. This paper describes the computational process of ice mass variations in Austfonna glacier ice cap. A total of 198 monthly GRACE and GRACE-FO global geopotential models, global hydrological model GLDAS NOAH and GIA model forced with ICE-5G global ice loading history were used to estimate the value of quadratic trend in terms of equivalent water height.
Influence of the Number of Control Points on Mobile Laser Scanning Accuracy
Nosek, Jakub ; Kalvoda, Petr ; Kuruc, Michal ; Volařík, Tomáš
Mobile laser scanning (MLS) is currently commonly used in a number of surveying applications, such as large-area mapping. This paper focuses on the effect of the number of control points on the resulting accuracy of MLS point clouds. The MLS cloud was compared with reference data in the form of a high-precision test point field and a terrestrial laser scanning reference cloud. Testing confirmed the manufacturer's requirements for the maximum spacing of control points 100 m. Matching with a higher density (up to 50 m spacing) allows eliminating local deformations in MLS clouds.
Usage of Photogrammetric Scanning of Cultural Heritage for the Purposes of the Cadastre of Real Estate
Kyseľ, Peter
The cadastral map collection contains maps of different origin and quality, and the less-quality maps are prevailing. Its effective renewal is needed. To meet this goal, it would be maybe necessary to use measurements from other sources besides the special measurements for the new mapping. The paper deals with the testing of exploitability of a photogrammetric measurement of cultural heritage for the cadastre. In the paper, the coordinates of building corners were determined using photogrammetry and compared to the existing numerical cadastral map. The precision and exploitability of the measurement for the cadastre was assessed based on these results. This and similar measurements could be suitable supplement for the measurements and could make the process of mapping more effective.
Dante's Inferno as an ArcGIS StoryMap
Münzberger, Josef
StoryMap was created to reconstruct the location and structure of Dante's Inferno. Its components (maps and 3D model) were built up based on an analysis of Comedy and early studies devoted to the mapping of Hell (A. Manetti, G. Galilei). Accompanied by selected verses and supporting text, they let the readers follow the story of determining the location, shape, and division of Hell. The literary work dated to the beginning of the 14th century is thus revived thanks to modern technologies and can be viewed from a non-traditional perspective.
Use of ArcGIS Dashboards to Visualize Covid-19 Pandemic Data
Brezničanová, Adriana
The report deals with the ArcGIS Dashboards application and its use in displaying Covid-19 pandemic data. The subject is a description of the functionality of the application and also its updating depending on the changing data. The paper describes the entire process of creating an application, from creating map layers in ArcGIS Pro, through data processing, publishing them to ArcGIS Online, creating a dashboard and updating it. The result is an approach to the creation of ArcGIS Dashboards and informing about the course of the pandemic on the created dashboard. The resulting dashboard shows the current situation in districts and regions, information on vaccinations, hospital occupancy and also historical data.

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