scholarly journals Application of Möbius coordinate transformation in evaluating Newton's integral

2011 ◽  
Vol 41 (2) ◽  
pp. 95-115
Author(s):  
Robert Tenzer ◽  
Vladislav Gladkikh
Keyword(s):  
Coordinate Transformation ◽  
Observation Point ◽  
Data Sets ◽  
Spherical Coordinates ◽  
Three Solutions ◽  
Digital Terrain ◽  
Near Zone ◽  
Newton’S Integral ◽  
Mass Volume ◽  
Gravitational Contribution

Application of Möbius coordinate transformation in evaluating Newton's integralWe propose a numerical scheme which efficiently combines various existing methods of solving the Newton's volume integral. It utilises the analytical solution of Newton's integral for tesseroid in computing the near-zone contribution to gravitational field quantities (potential and its first radial derivative). The far-zone gravitational contribution is computed using the expressions derived based on applying Molodensky's truncation coefficients to a spectral representation of Newton's integral. The weak singularity of Newton's integral is treated analytically using formulas for the gravitational contribution of the cylindrical mass volume centered with respect to the observation point. All three solutions are defined and evaluated in the system of polar spherical coordinates. A conversion of the geographical to polar spherical coordinates of input data sets (digital terrain and density models) is based on the Möbius transformation with an enhanced integration grid resolution at vicinity of the observation point.

scholarly journals Coordinate transformation parameters in Nepal by using neural network and SVD methods

2019 ◽  
Vol 9 (1) ◽  
pp. 22-28
Author(s):  
Kutubuddin Ansari ◽  
Prabin Gyawali ◽  
Prachand Man Pradhan ◽  
Kwan-Dong Park
Keyword(s):  
Neural Network ◽  
Coordinate Transformation ◽  
Data Sets ◽  
Extension Model ◽  
Global Positioning ◽  
Coordinate Measurements ◽  
Transformation Parameters ◽  
Artificial Neural Network Ann ◽  
Value Decomposition ◽  
Svd Method

Abstract The present study computes B-W extension model (extended Bursa-Wolf model) coordinate transformation parameters from World Geodetic System 1984 (WGS-84) to the Everest datum namely Everest (1830) and Everest (1956) using records of coordinate measurements from Global Positioning System (GPS) observable across Nepal region. Synthetic or modeled coordinates were determined by using the Artificial Neural Network (ANN) and Singular Value Decomposition (SVD) methods. We studied 9-transformation parameters with the help of the ANN technique and validated the outcomes with the SVD method. The comparative analysis of the ANN, as well as SVD methods, was done with the observed output following one way ANOVA test. The analysis showed that the null hypothesis for both datums were acceptable and suggesting all models statistically significantly equivalent to each other. The outcomes from this study would complement a relatively better understanding of the techniques for coordinate transformation and precise coordinate assignment while assimilating data sets from different resources.

Potential fields and their partial derivatives produced by a 2D homogeneous polygonal source: A summary with some revisions

Geophysics ◽  
2011 ◽  
Vol 76 (4) ◽  
pp. L29-L34 ◽  
Author(s):  
Zhen Jia ◽  
Shiguo Wu
Keyword(s):  
Magnetic Field ◽  
Cross Section ◽  
Observation Point ◽  
Potential Fields ◽  
Data Sets ◽  
Partial Derivatives ◽  
First Order ◽  
Gravity And Magnetic ◽  
Derivatives Of ◽  
The Magnetic Field

We summarized and revised the present forward modeling methods for calculating the gravity- and magnetic-field components and their partial derivatives of a 2D homogeneous source with a polygonal cross section. The responses of interest include the gravity-field components and their first- and second-order partial derivatives and the magnetic-field components and their first-order partial derivatives. The revised formulas consist of several basic quantities that are common in all the formulations. A singularity appears when the observation point coincides with a polygon vertex. This singularity is removable for the gravity formulas but not for the others. The compact forms of the revised formulas make them easy to implement. We compare the gravity- and magnetic-field components and their partial derivatives produced by a 2D prism whose polygonal cross section approximates a cylinder with the corresponding analytical fields and partial derivatives of the cylinder. The perfect fittings presented by both data sets confirm the reliability of the updated formulas.

scholarly journals DIGITAL TERRAIN MODELS FROM MOBILE LASER SCANNING DATA IN MORAVIAN KARST

2016 ◽  
Vol XLI-B3 ◽  
pp. 387-394 ◽  
Author(s):  
N. Tyagur ◽  
M. Hollaus
Keyword(s):  
Czech Republic ◽  
Laser Scanning ◽  
Point Clouds ◽  
Low Noise ◽  
Data Sets ◽  
The Czech Republic ◽  
Digital Terrain ◽  
3D Point Clouds ◽  
Moravian Karst

During the last ten years, mobile laser scanning (MLS) systems have become a very popular and efficient technology for capturing reality in 3D. A 3D laser scanner mounted on the top of a moving vehicle (e.g. car) allows the high precision capturing of the environment in a fast way. Mostly this technology is used in cities for capturing roads and buildings facades to create 3D city models. In our work, we used an MLS system in Moravian Karst, which is a protected nature reserve in the Eastern Part of the Czech Republic, with a steep rocky terrain covered by forests. For the 3D data collection, the Riegl VMX 450, mounted on a car, was used with integrated IMU/GNSS equipment, which provides low noise, rich and very dense 3D point clouds. <br><br> The aim of this work is to create a digital terrain model (DTM) from several MLS data sets acquired in the neighbourhood of a road. The total length of two covered areas is 3.9 and 6.1 km respectively, with an average width of 100 m. For the DTM generation, a fully automatic, robust, hierarchic approach was applied. The derivation of the DTM is based on combinations of hierarchical interpolation and robust filtering for different resolution levels. For the generation of the final DTMs, different interpolation algorithms are applied to the classified terrain points. The used parameters were determined by explorative analysis. All MLS data sets were processed with one parameter set. As a result, a high precise DTM was derived with high spatial resolution of 0.25 x 0.25 m. The quality of the DTMs was checked by geodetic measurements and visual comparison with raw point clouds. The high quality of the derived DTM can be used for analysing terrain changes and morphological structures. Finally, the derived DTM was compared with the DTM of the Czech Republic (DMR 4G) with a resolution of 5 x 5 m, which was created from airborne laser scanning data. The vertical accuracy of the derived DTMs is around 0.10 m.

scholarly journals DIGITAL TERRAIN MODELS FROM MOBILE LASER SCANNING DATA IN MORAVIAN KARST

2016 ◽  
Vol XLI-B3 ◽  
pp. 387-394 ◽  
Author(s):  
N. Tyagur ◽  
M. Hollaus
Keyword(s):  
Czech Republic ◽  
Laser Scanning ◽  
Point Clouds ◽  
Low Noise ◽  
Data Sets ◽  
The Czech Republic ◽  
Digital Terrain ◽  
3D Point Clouds ◽  
Moravian Karst

During the last ten years, mobile laser scanning (MLS) systems have become a very popular and efficient technology for capturing reality in 3D. A 3D laser scanner mounted on the top of a moving vehicle (e.g. car) allows the high precision capturing of the environment in a fast way. Mostly this technology is used in cities for capturing roads and buildings facades to create 3D city models. In our work, we used an MLS system in Moravian Karst, which is a protected nature reserve in the Eastern Part of the Czech Republic, with a steep rocky terrain covered by forests. For the 3D data collection, the Riegl VMX 450, mounted on a car, was used with integrated IMU/GNSS equipment, which provides low noise, rich and very dense 3D point clouds. &lt;br&gt;&lt;br&gt; The aim of this work is to create a digital terrain model (DTM) from several MLS data sets acquired in the neighbourhood of a road. The total length of two covered areas is 3.9 and 6.1 km respectively, with an average width of 100 m. For the DTM generation, a fully automatic, robust, hierarchic approach was applied. The derivation of the DTM is based on combinations of hierarchical interpolation and robust filtering for different resolution levels. For the generation of the final DTMs, different interpolation algorithms are applied to the classified terrain points. The used parameters were determined by explorative analysis. All MLS data sets were processed with one parameter set. As a result, a high precise DTM was derived with high spatial resolution of 0.25 x 0.25 m. The quality of the DTMs was checked by geodetic measurements and visual comparison with raw point clouds. The high quality of the derived DTM can be used for analysing terrain changes and morphological structures. Finally, the derived DTM was compared with the DTM of the Czech Republic (DMR 4G) with a resolution of 5 x 5 m, which was created from airborne laser scanning data. The vertical accuracy of the derived DTMs is around 0.10 m.

scholarly journals Identification of Archaeologically Relevant Areas Using Open Geodata

2020 ◽  
Vol 70 (3) ◽  
pp. 107-125
Author(s):  
M. Fabian Meyer-Heß
Keyword(s):  
Research Topic ◽  
Geospatial Data ◽  
Light Detection And Ranging ◽  
Data Sets ◽  
Full Potential ◽  
Automated Classification ◽  
Digital Terrain ◽  
Landscape Models ◽  
Terrain Models ◽  
Digital Landscape

Abstract Light detection and ranging (LiDAR) and digital terrain models (DTM) revolutionized archeological prospection in the last two decades. Using the new technique, comprehensive areal detections of archeological relief structures (field monuments) hidden under dense vegetation became possible and archeologists found new sites even in well-known areas. In times of Open Geodata policies, archeologists have access to geospatial data sets such as DTM. Assessing its full potential requires automated workflows, which is a recent research topic in archeological research. However, all approaches, both manually and automated, are affected by misclassifications caused by confusions of archeological and modern structures. Digital landscape models (DLM) help differentiating structures by their location. Concerning these data, only 74% of the total area of Westphalia and Lippe need archeological investigation, increasing precision of automated classification approaches.

Alternative Methods for Developing and Assessing the Accuracy of UAV-Derived DEMs

2019 ◽  
pp. 1175-1196
Author(s):  
Dion J. Wiseman ◽  
Jurjen van der Sluijs
Keyword(s):  
High Resolution ◽  
Accuracy Assessment ◽  
Point Clouds ◽  
Alternative Methods ◽  
Data Sets ◽  
Digital Terrain ◽  
Terrain Models ◽  
Dense Point ◽  
Data Points ◽  
Derived Data

Digital terrain models are invaluable datasets that are frequently used for visualizing, modeling, and analyzing Earth surface processes. Accurate models covering local scale landscape features are often very expensive and have poor temporal resolution. This research investigates the utility of UAV acquired imagery for generating high resolution terrain models and provides a detailed accuracy assessment according to recommended protocols. High resolution UAV imagery was acquired over a localized dune complex in southwestern Manitoba, Canada and two alternative workflows were evaluated for extracting point clouds. UAV-derived data points were then compared to reference data sets acquired using mapping grade GPS receivers and a total station. Results indicated that the UAV imagery was capable of producing dense point clouds and high resolution terrain models with mean errors as low as -0.15 m and RMSE values of 0.42 m depending on the resolution of the image dataset and workflow employed.

scholarly journals SPECTRAL ANALYSIS OF THE SEISMIC IMPACT IN NEAR ZONE OF STRONG EARTHQUAKE AND EFFECT DETAILS

2016 ◽  
Author(s):  
Э.Г. Геодакян ◽  
Дж.К. Карапетян ◽  
В.Б. Заалишвили ◽  
С.М. Оганесян ◽  
С.Н. Саргсян
Keyword(s):  
Spectral Analysis ◽  
Strong Earthquake ◽  
Seismic Waves ◽  
Geological Structure ◽  
Observation Point ◽  
Geological Environment ◽  
Seismic Effects ◽  
Near Zone ◽  
Seismic Impact ◽  
Instrumental Records

На основе цифровых инструментальных записей исследованы влияние геологической среды распространения сейсмических волн и геологического строения «инженерного» слоя под пунктом наблюдения на амплитудный уровень и частотный состав сейсмических воздействий The influence of the geological environment of seismic waves and the geological structure of the «engineering» layer under observation point on the level of amplitude and frequency composition of seismic effects are investigated on the basis of digital instrumental records

scholarly journals How Well Do We Know Europa’s Topography? An Evaluation of the Variability in Digital Terrain Models of Europa

2021 ◽  
Vol 13 (24) ◽  
pp. 5097
Author(s):  
Michael T. Bland ◽  
Randolph L. Kirk ◽  
Donna M. Galuszka ◽  
David P. Mayer ◽  
Ross A. Beyer ◽  
...  
Keyword(s):  
Horizontal Resolution ◽  
Data Sets ◽  
Digital Terrain Models ◽  
Matching Accuracy ◽  
Extraterrestrial Life ◽  
Correlation Kernel ◽  
Digital Terrain ◽  
Terrain Models ◽  
Ice Shell ◽  
Pixel Scale

Jupiter’s moon Europa harbors one of the most likely environments for extant extraterrestrial life. Determining whether Europa is truly habitable requires understanding the structure and thickness of its ice shell, including the existence of perched water or brines. Stereo-derived topography from images acquired by NASA Galileo’s Solid State Imager (SSI) of Europa are often used as a constraint on ice shell structure and heat flow, but the uncertainty in such topography has, to date, not been rigorously assessed. To evaluate the current uncertainty in Europa’s topography we generated and compared digital terrain models (DTMs) of Europa from SSI images using both the open-source Ames Stereo Pipeline (ASP) software and the commercial SOCET SET® software. After first describing the criteria for assessing stereo quality in detail, we qualitatively and quantitatively describe both the horizontal resolution and vertical precision of the DTMs. We find that the horizontal resolution of the SOCET SET® DTMs is typically 8–11× the root mean square (RMS) pixel scale of the images, whereas the resolution of the ASP DTMs is 9–13× the maximum pixel scale of the images. We calculate the RMS difference between the ASP and SOCET SET® DTMs as a proxy for the expected vertical precision (EP), which is a function of the matching accuracy and stereo geometry. We consistently find that the matching accuracy is ~0.5 pixels, which is larger than well-established “rules of thumb” that state that the matching accuracy is 0.2–0.3 pixels. The true EP is therefore ~1.7× larger than might otherwise be assumed. In most cases, DTM errors are approximately normally distributed, and errors that are several times the derived EP occur as expected. However, in two DTMs, larger errors (differences) occur and correlate with real topography. These differences primarily result from manual editing of the SOCET SET® DTMs. The product of the DTM error and the resolution is typically 4–8 pixel2 if calculated using the RMS image scale for SOCET SET® DTMs and the maximum images scale for the ASP DTMs, which is consistent with recent work using martian data sets and suggests that the relationship applies more broadly. We evaluate how ASP parameters affect DTM quality and find that using a smaller subpixel refinement kernel results in DTMs with smaller (better) resolution but, in some cases, larger gaps, which are sometimes reduced by increasing the size of the correlation kernel. We conclude that users of ASP should always systematically evaluate the choice of parameters for a given dataset.

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