New geoid models computation in the Southeast part of Brazil

2021 ◽  
Author(s):  
Valeria Silva ◽  
Gabriel Guimarães ◽  
Denizar Blitkow ◽  
Ana Cristina Matos
Keyword(s):  
Gravity Data ◽  
Digital Terrain Model ◽  
Minas Gerais ◽  
Data Sets ◽  
Geoid Model ◽  
Terrain Model ◽  
Paulo State ◽  
Normal Heights ◽  
Field Works ◽  
Gnss Measurements

<p>In the last decade, big efforts have been undertaken in terms of gravity surveys in the Southeast part of Brazil. First of all, São Paulo state has gravity data coverage quite completed in terms of 5’ resolution. Second, in the last few years, some field works have been carried out in Minas Gerais state. The purpose of gravity densification is not only to improve the quality of geoid (quasi-geoid) models in Brazil, but also to contribute to the geodetic infrastructure, in particular, at the moment, for the establishment of the International Height Reference Frame, where two of six planned stations are located in the densification area. These efforts resulted in the computation of two quasi-geoid models in the Southeast region of Brazil. The decision is to compute a quasi-geoid instead of a geoid model, once since 2018, the Brazilian vertical system is based on normal heights. The Minas Gerais model was computed using Least Squares Collocation, via Fast Collocation. The spectral decomposition was employed in the technique for quasi-geoid model computation, where the reference field was represented by XGM2019 up to degree and order 200. The model was compared with GNSS/leveling in order to check the consistency of two different data sets. Two quasi-geoidal models for the São Paulo state have been computed. Numerical integration through the Fast Fourier Transform (FFT) was used to perform the integral. The Molodensky gravity anomaly was determined in a 5’ grid, reduced and restored using the Residual Terrain Model (RTM) technique and the XGM2019 with the degree and order 250 and 720. The validation for the São Paulo quasi-geoid model is based on the GNSS measurements in the leveling network too.  The Digital Terrain Model SRTM15 plus was used in the continent and the ocean areas in both states.</p>

scholarly journals CLASSIC: a semi-distributed rainfall-runoff modelling system

2007 ◽  
Vol 11 (1) ◽  
pp. 516-531 ◽  
Author(s):  
S. M. Crooks ◽  
P. S. Naden
Keyword(s):  
Spatial Scales ◽  
Digital Terrain Model ◽  
Flood Frequency ◽  
Data Sets ◽  
Rainfall Runoff ◽  
Terrain Model ◽  
Flow Duration Curves ◽  
Rainfall Runoff Model ◽  
The Uk ◽  
Modelling System

Abstract. This paper describes the development of a semi-distributed conceptual rainfall–runoff model, originally formulated to simulate impacts of climate and land-use change on flood frequency. The model has component modules for soil moisture balance, drainage response and channel routing and is grid-based to allow direct incorporation of GIS- and Digital Terrain Model (DTM)-derived data sets into the initialisation of parameter values. Catchment runoff is derived from the aggregation of components of flow from the drainage module within each grid square and from total routed flow from all grid squares. Calibration is performed sequentially for the three modules using different objective functions for each stage. A key principle of the modelling system is the concept of nested calibration, which ensures that all flows simulated for points within a large catchment are spatially consistent. The modelling system is robust and has been applied successfully at different spatial scales to three large catchments in the UK, including comparison of observed and modelled flood frequency and flow duration curves, simulation of flows for uncalibrated catchments and identification of components of flow within a modelled hydrograph. The role of such a model in integrated catchment studies is outlined.

The experimental geoid 2020 – the first joint geoid model for the North American and Pacific Geopotential Datum 

2021 ◽  
Author(s):  
Yan Ming Wang ◽  
Xiaopeng Li ◽  
Kevin Ahlgren ◽  
Jordan Krcmaric ◽  
Ryan Hardy ◽  
...  
Keyword(s):  
North American ◽  
Gravity Data ◽  
The United States ◽  
Geodetic Survey ◽  
Airborne Gravity ◽  
Data Sets ◽  
National Geodetic Survey ◽  
Geoid Model ◽  
Satellite Gravity ◽  
The North

<p>For the upcoming North American-Pacific Geopotential Datum of 2022, the National Geodetic Survey (NGS), the Canadian Geodetic Survey (CGS) and the National Institute of Statistics and Geography of Mexico (INEGI) computed the first joint experimental gravimetric geoid model (xGEOID) on 1’x1’ grids that covers a region bordered by latitude 0 to 85 degree, longitude 180 to 350 degree east. xGEOID20 models are computed using terrestrial gravity data, the latest satellite gravity model GOCO06S, altimetric gravity data DTU15, and an additional nine airborne gravity blocks of the GRAV-D project, for a total of 63 blocks. In addition, a digital elevation model in a 3” grid was produced by combining MERIT, TanDEM-X, and USGS-NED and used for the topographic/gravimetric reductions. The geoid models computed from the height anomalies (NGS) and from the Helmert-Stokes scheme (CGS) were combined using two different weighting schemes, then evaluated against the independent GPS/leveling data sets. The models perform in a very similar way, and the geoid comparisons with the most accurate Geoid Slope Validation Surveys (GSVS) from 2011, 2014 and 2017 indicate that the relative geoid accuracy could be around 1-2 cm baseline lengths up to 300 km for these GSVS lines in the United States. The xGEOID20 A/B models were selected from the combined models based on the validation results. The geoid accuracies were also estimated using the forward modeling.</p>

scholarly journals Simulation of the Indonesian land gravity data using a digital terrain model data

2004 ◽  
Vol 56 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Leni Sophia Heliani ◽  
Yoichi Fukuda ◽  
Shuzo Takemoto
Keyword(s):  
Gravity Data ◽  
Digital Terrain Model ◽  
Model Data ◽  
Terrain Model ◽  
Digital Terrain

An improved topographic database for King George Island: compilation, application and outlook

2001 ◽  
Vol 13 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Matthias Braun ◽  
Jefferson C. Simões ◽  
Steffen Vogt ◽  
Ulisses F. Bremer ◽  
Norbert Blindow ◽  
...  
Keyword(s):  
Satellite Image ◽  
Digital Terrain Model ◽  
Data Sets ◽  
Image Mosaic ◽  
King George Island ◽  
Differential Gps ◽  
Terrain Model ◽  
Digital Database ◽  
Topographic Information ◽  
Potential Applications

A new topographic database for King George Island, one of the most visited areas in Antarctica, is presented. Data from differential GPS surveys, gained during the summers 1997/98 and 1999/2000, were combined with up to date coastlines from a SPOT satellite image mosaic, and topographic information from maps as well as from the Antarctic Digital Database. A digital terrain model (DTM) was generated using ARC/INFO GIS. From contour lines derived from the DTM and the satellite image mosaic a satellite image map was assembled. Extensive information on data accuracy, the database as well as on the criteria applied to select place names is given in the multilingual map. A lack of accurate topographic information in the eastern part of the island was identified. It was concluded that additional topographic surveying or radar interferometry should be conducted to improve the data quality in this area. In three case studies, the potential applications of the improved topographic database are demonstrated. The first two examples comprise the verification of glacier velocities and the study of glacier retreat from the various input data-sets as well as the use of the DTM for climatological modelling. The last case study focuses on the use of the new digital database as a basic GIS (Geographic Information System) layer for environmental monitoring and management on King George Island.

scholarly journals GRAVIMETRIC GEOID MODELLING OVER PENINSULAR MALAYSIA USING TWO DIFFERENT GRIDDING APPROACHES FOR COMBINING FREE AIR ANOMALY

2019 ◽  
Vol XLII-4/W16 ◽  
pp. 515-522
Author(s):  
M. F. Pa’suya ◽  
A. H. M. Din ◽  
J. C. McCubbine ◽  
A. H. Omar ◽  
Z. M. Amin ◽  
...  
Keyword(s):  
Gravity Data ◽  
Reference Signal ◽  
Digital Terrain Model ◽  
Peninsular Malaysia ◽  
Airborne Gravity ◽  
Geopotential Model ◽  
Gravimetric Geoid ◽  
Geoid Model ◽  
Free Air ◽  
Free Air Anomaly

Abstract. We investigate the use of the KTH Method to compute gravimetric geoid models of Malaysian Peninsular and the effect of two differing strategies to combine and interpolate terrestrial, marine DTU17 free air gravity anomaly data at regular grid nodes. Gravimetric geoid models were produced for both free air anomaly grids using the GOCE-only geopotential model GGM GO_CONS_GCF_2_SPW_R4 as the long wavelength reference signal and high-resolution TanDEM-X global digital terrain model. The geoid models were analyzed to assess how the different gridding strategies impact the gravimetric geoid over Malaysian Peninsular by comparing themto 172 GNSS-levelling derived geoid undulations. The RMSE of the two sets of gravimetric geoid model / GNSS-levelling residuals differed by approx. 26.2 mm. When a 4-parameter fit is used, the difference between the RMSE of the residuals reduced to 8 mm. The geoid models shown here do not include the latest airborne gravity data used in the computation of the official gravimetric geoid for the Malaysian Peninsular, for this reason they are not as precise.

scholarly journals DETERMINATION OF GEOGRAPHIC POSITION OF OBJECT BY APPLYING 3D POLAR OBSERVATIONS

Aviation ◽  
2010 ◽  
Vol 14 (2) ◽  
pp. 43-48 ◽  
Author(s):  
Algimantas Zakarevičius ◽  
Vladislovas Česlovas Aksamitauskas ◽  
Algimantas Jakučionis ◽  
Arminas Stanionis
Keyword(s):  
Digital Terrain Model ◽  
Geoid Model ◽  
Normal Height ◽  
Cartesian Coordinates ◽  
Object A ◽  
Terrain Model ◽  
The Earth ◽  
Geographic Position ◽  
Geodetic Height ◽  
Airport Runway

The geographic position of an object is determined by geodetic latitude, geodetic longitude, geodetic and normal height, and height of the object above the surface of the earth. To determine the geographic position of an object, a technologic scheme is recommended: by applying 3D polar observations, the 3D Cartesian coordinates of the object in the local horizontal coordinate system (for example, with an airport runway tied system) are determined; local horizontal 3D Cartesian coordinates are recomputed into the system of geocentric equatorial 3D Cartesian coordinates; the geodetic coordinates (geodetic latitude, geodetic longitude, and geodetic height) are computed from the geocentric equatorial 3D Cartesian coordinates; based on information about geodetic height and the digital geoid model, the normal height of the object is computed; and object height above the earth is computed from normal height and the digital terrain model. Algorithms for the realisation of this technologic scheme are presented. Santrauka Objekto geografine padetis apibūdinama geodezine platuma, geodezine ilguma, geodeziniu bei normaliniu aukščiais ir objekto aukščiu virš Žemes paviršiaus. Objekto geografinei padečiai nustatyti rekomenduojama tokia technologine schema: taikant erdvinius polinius matavimus, nustatomos objekto erdvines stačiakampes koordinates vietineje (pvz., oro uosto) horizontineje koordinačiu sistemoje; vietines horizontines erdvines stačiakampes koordinates perskaičiuojamos i geocentriniu ekvatoriniu erdviniu stačiakampiu koordinačiu sistema; pagal geocentrines ekvatorines erdvines stačiakampes koordinates apskaičiuojamos geodezines koordinates (geodezine platuma, geodezine ilguma ir geodezinis aukštis); žinant geodezini aukšti ir turint skaitmenini geoido modeli, skaičiuojamas objekto normalinis aukštis; turint normalini aukšti ir skaitmenini reljefo modeli, apskaičiuojamas objekto aukštis virš Žemes paviršiaus. Pateikiami algoritmai šiai technologinei schemai realizuoti.

scholarly journals SimpleForest - a comprehensive tool for 3d reconstruction of trees from forest plot point clouds

2021 ◽  
Author(s):  
Jan Hackenberg ◽  
Kim Calders ◽  
Miro Demol ◽  
Pasi Raumonen ◽  
Alexandre Piboule ◽  
...  
Keyword(s):  
Digital Terrain Model ◽  
Point Clouds ◽  
Forest Plot ◽  
Data Sets ◽  
Cross Sectional ◽  
Data Set ◽  
Terrain Model ◽  
Digital Terrain ◽  
Pipe Model ◽  
The One

The here-on presented SimpleForest is written in C++ and published under GPL v3. As input data SimpleForest utilizes forestry scenes recorded as terrestrial laser scan clouds. SimpleForest provides a fully automated pipeline to model the ground as a digital terrain model, then segment the vegetation and finally build quantitative structure models of trees (QSMs) consisting of up to thousands of topologically ordered cylinders. These QSMs allow us to calculate traditional forestry metrics such as diameter at breast height, but also volume and other structural metrics that are hard to measure in the field. Our volume evaluation on three data sets with destructive volumes show high prediction qualities with concordance correlation coefficient CCC (r2 adj.) of 0.91 (0.87), 0.94 (0.92) and 0.97 (0.93) for each data set respectively. We combine two common assumptions in plant modeling The sum of cross sectional areas after a branch junction equals the one before the branch junction (Pipe Model Theory) and Twigs are self-similar (West, Brown and Enquist model). As even sized twigs correspond to even sized cross sectional areas for twigs we define the Reverse Pipe Radius Branchorder (RPRB) as the square root of the number of supported twigs. The prediction model radius = B 0 ∗ RP RB relies only on correct topological information and can be used to detect and correct overestimated cylinders. In QSM building the necessity to handle overestimated cylinders is well known. The RPRB correction performs better with a CCC (r2 adj.) of 0.97 (0.93) than former published ones 0.80 (0.88) and 0.86 (0.85) in our validation. We encourage forest ecologists to analyze output parameters such as the GrowthVolume published in earlier works, but also other parameters such as the GrowthLength, VesselVolume and RPRB which we define in this manuscript.

scholarly journals The MASCOT landing area on asteroid (162173) Ryugu: Stereo-photogrammetric analysis using images of the ONC onboard the Hayabusa2 spacecraft

2019 ◽  
Vol 632 ◽  
pp. L4 ◽  
Author(s):  
F. Preusker ◽  
F. Scholten ◽  
S. Elgner ◽  
K.-D. Matz ◽  
S. Kameda ◽  
...  
Keyword(s):  
High Resolution ◽  
Control Point ◽  
Digital Terrain Model ◽  
Landing Site ◽  
Surface Model ◽  
Data Sets ◽  
Camera System ◽  
Terrain Model ◽  
Digital Terrain ◽  
Camera Orientation

A high-resolution 3D surface model, map-projected to a digital terrain model (DTM), and precisely ortho-rectified context images (orthoimages) of MASCOT landing site area are important data sets for the scientific analysis of relevant data that have been acquired with MASCOT’s image camera system MASCam and other instruments (e.g., the radiometer MARA and the magnetometer MASMag). We performed a stereo-photogrammetric (SPG) analysis of 1050 images acquired from the Hayabusa2 Optical Navigation Camera system (ONC) during the asteroid characterization phase and the MASCOT release phase in early October 2018 to construct a photogrammetric control point network of asteroid (162173) Ryugu. We validated existing rotational parameters for Ryugu and improved the camera orientation (position and pointing) of the ONC images to decimeter accuracy using SPG bundle block adjustment. We produced a high-resolution DTM of the entire MASCOT landing site area. Finally, based on this DTM, a set of orthoimages from the highest-resolution ONC images around MASCOT’s final rest position complements the results of this analysis.

scholarly journals Mapping with Pléiades—End-to-End Workflow

2019 ◽  
Vol 11 (17) ◽  
pp. 2052 ◽  
Author(s):  
Roland Perko ◽  
Hannes Raggam ◽  
Peter M. Roth
Keyword(s):  
Digital Terrain Model ◽  
Building Blocks ◽  
Surface Model ◽  
Data Sets ◽  
3D Mapping ◽  
Digital Surface Model ◽  
Terrain Model ◽  
Digital Terrain ◽  
Surface Models ◽  
End To End

In this work, we introduce an end-to-end workflow for very high-resolution satellite-based mapping, building the basis for important 3D mapping products: (1) digital surface model, (2) digital terrain model, (3) normalized digital surface model and (4) ortho-rectified image mosaic. In particular, we describe all underlying principles for satellite-based 3D mapping and propose methods that extract these products from multi-view stereo satellite imagery. Our workflow is demonstrated for the Pléiades satellite constellation, however, the applied building blocks are more general and thus also applicable for different setups. Besides introducing the overall end-to-end workflow, we need also to tackle single building blocks: optimization of sensor models represented by rational polynomials, epipolar rectification, image matching, spatial point intersection, data fusion, digital terrain model derivation, ortho rectification and ortho mosaicing. For each of these steps, extensions to the state-of-the-art are proposed and discussed in detail. In addition, a novel approach for terrain model generation is introduced. The second aim of the study is a detailed assessment of the resulting output products. Thus, a variety of data sets showing different acquisition scenarios are gathered, allover comprising 24 Pléiades images. First, the accuracies of the 2D and 3D geo-location are analyzed. Second, surface and terrain models are evaluated, including a critical look on the underlying error metrics and discussing the differences of single stereo, tri-stereo and multi-view data sets. Overall, 3D accuracies in the range of 0 . 2 to 0 . 3 m in planimetry and 0 . 2 to 0 . 4 m in height are achieved w.r.t. ground control points. Retrieved surface models show normalized median absolute deviations around 0 . 9 m in comparison to reference LiDAR data. Multi-view stereo outperforms single stereo in terms of accuracy and completeness of the resulting surface models.

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