The generalized gravity anomaly: Endoscopic microgravity

Geophysics ◽  
1991 ◽  
Vol 56 (5) ◽  
pp. 712-723 ◽  
Author(s):  
J. Lakshmanan
Keyword(s):  
Underground Structure ◽  
Bouguer Anomaly ◽  
Digital Terrain Model ◽  
Gravity Anomalies ◽  
Underground Structures ◽  
Terrain Model ◽  
Digital Terrain ◽  
Generalized Inversion ◽  
Gravity Measurements ◽  
The One

Various underground 3-D gravity surveys have necessitated a generalization of the usual gravity corrections and of the Bouguer anomaly. The method presented here compares raw, time‐dependent gravity measurements, to a model’s total theoretical field, including known fields: moon, sun, 1967 Reference Ellipsoid, oceans; partially known fields: due to a single digital terrain model of known geometry but of unknown densities; and unknown fields due to underground structures of unknown shapes and of unknown densities. For a single‐density model, the corresponding first‐degree residual is close in concept to the Bouguer anomaly. To best determine underground structure, generalized inversion then leads to determination of the one or several densities and of one or several “regional” parameters, which minimize residuals. The suggested method is mainly advantageous in special types of gravity surveys, such as rugged terrain, or in the case of underground surveys, where conventional corrections, with a preset terrain density can possibly lead to substantial errors. Two field examples are developed (1) the Cheops pyramid survey, where the processing of gravity measurements inside, above, and around the pyramid led to an evaluation of the structure’s overall density and of density changes in the structure; and (2) the Coche hydroelectric tunnel in the Alps, where the method leads to a 3-D model explaining the very strong gravity anomalies observed in the tunnel and on the mountain above it.

scholarly journals BACKPACK MOBILE MAPPING SOLUTION FOR DTM EXTRACTION OF LARGE INACCESSIBLE SPACES

2019 ◽  
Vol XLII-2/W15 ◽  
pp. 473-480
Author(s):  
F. Fassi ◽  
L. Perfetti
Keyword(s):  
Digital Terrain Model ◽  
Small Scale ◽  
Mobile Mapping ◽  
Terrain Model ◽  
Digital Terrain ◽  
Mapping System ◽  
Mobile Mapping System ◽  
The One ◽  
Mapping Solution

<p><strong>Abstract.</strong> The paper presents the case study of the complete 3D survey of the area of the Fort of Pietole in Borgo Virgilio using the Leica Pegasus Backpack wearable Mobile Mapping System (MMS). Surveying the site is challenging because of its complex topology on the one hand (with notably narrow passages) and because of the presence of vegetation on the other. The framework within which this research takes place is the Fort of Pietole survey project that aims at the extraction of the Digital Terrain Model (DTM) of the area and the georeferencing of the fort defensive structures. The requirement of the project is the 3D reconstruction of the whole area at an accuracy that stands between a big scale environmental survey and a small-scale architectonic survey (1&amp;thinsp;:&amp;thinsp;500).</p> <p>The project is the opportunity to discuss the state of the art of wearable MMS, and to test the versatility and accuracy outcomes of the Pegasus Backpack under varying and challenging condition (indoor-outdoor, even-uneven pavement, satellite covered-denied areas) with the ambitious goal to use only the backpack MMS to record all the data from the DTM to the indoor narrow structures.</p>

scholarly journals Correlation among Earthwork and Cropmark Anomalies within Archaeological Landscape Investigation by Using LiDAR and Multispectral Technologies from UAV

Drones ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 72
Author(s):  
Diego Ronchi ◽  
Marco Limongiello ◽  
Salvatore Barba
Keyword(s):  
Vegetation Indices ◽  
Three Dimensional ◽  
Digital Terrain Model ◽  
Buried Structures ◽  
Aerial Photos ◽  
Terrain Model ◽  
Survey Techniques ◽  
Digital Terrain ◽  
Vegetation Maps ◽  
The One

This project aimed to systematically investigate the archaeological remains of the imperial Domitian villa in Sabaudia (Italy), using different three-dimensional survey techniques. Particular attention in the research was paid to the identification and documentation of traces that buried structures left on the surface occupied by the villa, which extended for 46 hectares, an area that was fully covered with structures. Since a dense pine forest was planted during the 1940s and is currently covering the site, this contribution investigates particularly the correlation among the presence of cropmarks, identifiable with the processing of multispectral maps and vegetation indices from RGB images, and earthwork anomalies identified in a Digital Terrain Model (DTM) built, by utilizing a light detection and ranging (LiDAR) flight from an Unmanned Aerial Vehicle (UAV). The study demonstrates how the use of vegetation maps—calculated starting from RGB and multispectral aerial photos—can provide a more expeditious preliminary analysis on the position and extension of areas characterized by the presence of buried structures, but also that, in order to investigate in-depth a context in similar conditions, the most effective approach remains the one based on LiDAR technology. The integration between the two techniques may prove fruitful in limiting the extension of the areas to be investigated with terrestrial survey techniques.

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 Assessing lahars from ice-capped volcanoes using ASTER satellite data, the SRTM DTM and two different flow models: case study on Iztaccíhuatl (Central Mexico)

2008 ◽  
Vol 8 (3) ◽  
pp. 559-571 ◽  
Author(s):  
D. Schneider ◽  
H. Delgado Granados ◽  
C. Huggel ◽  
A. Kääb
Keyword(s):  
Digital Terrain Model ◽  
Interaction Model ◽  
Summit Crater ◽  
Fumarolic Activity ◽  
Model Calculations ◽  
Crater Lakes ◽  
Flow Models ◽  
Terrain Model ◽  
Digital Terrain ◽  
The One

Abstract. Lahars frequently affect the slopes of ice-capped volcanoes. They can be triggered by volcano-ice interactions during eruptions but also by processes such as intense precipitation or by outbursts of glacial water bodies not directly related to eruptive activity. We use remote sensing, GIS and lahar models in combination with ground observations for an initial lahar hazard assessment on Iztaccíhuatl volcano (5230 m a.s.l.), considering also possible future developments of the glaciers on the volcano. Observations of the glacial extent are important for estimations of future hazard scenarios, especially in a rapidly changing tropical glacial environment. In this study, analysis of the glaciers on Iztaccíhuatl shows a dramatic retreat during the last 150 years: the glaciated area in 2007 corresponds to only 4% of the one in 1850 AD and the glaciers are expected to survive no later than the year 2020. Most of the glacial retreat is considered to be related to climate change but in-situ observations suggest also that geo- and hydrothermal heat flow at the summit-crater area can not be ruled out, as emphasized by fumarolic activity documented in a former study. However, development of crater lakes and englacial water reservoirs are supposed to be a more realistic scenario for lahar generation than sudden ice melting by rigorous volcano-ice interaction. Model calculations show that possible outburst floods have to be larger than ~5×105 m3 or to achieve an H/L ratio (Height/runout Length) of 0.2 and lower in order to reach the populated lower flanks. This threshold volume equals 2.4% melted ice of Iztaccíhuatl's total ice volume in 2007, assuming 40% water and 60% volumetric debris content of a potential lahar. The model sensitivity analysis reveals important effects of the generic type of the Digital Terrain Model (DTM) used on the results. As a consequence, the predicted affected areas can vary significantly. For such hazard zonation, we therefore suggest the use of different types of DTMs and flow models, followed by a careful comparison and interpretation of the results.

Selection of Appropriate Scale of Relief Model

2017 ◽  
Author(s):  
Marta Kuzma ◽  
Marcin Lisowski
Keyword(s):  
Large Scale ◽  
Digital Terrain Model ◽  
Terrain Model ◽  
Digital Terrain ◽  
Vertical Scale ◽  
Land Surveying ◽  
Correct Representation ◽  
The Subject ◽  
The One ◽  
Selection Of

This paper presents the application of digital terrain model in developing a relief model. The digital terrain model served as the basis for the relief model. The research has taken into account the subject of combining different data in order to develop a numerical model of the land − surveying, bathymetry, maps. Another issue addressed was the one of vertical scale or exceeding it in the developed model. Its appropriate selection allows the correct representation of the terrain geomorphology. The paper presents research in carrying out relief model of Szczesliwicki Park in Warsaw. The results show the link between the vertical scale or exceeding it and the accuracy (correctness) of relief model in large-scale descriptions. In addition, a verification of models was made with the use of a scanner that uses structural light.

scholarly journals The Application of Decision Binary Trees to Assess the Usefulness of The Digital Terrain Model in Studying the Relationships Between Relief and Vegetation in The Polish High Tatra

2006 ◽  
Vol 12 (1) ◽  
pp. 305-313
Author(s):  
Karol Kącki
Keyword(s):  
Land Cover ◽  
Plant Communities ◽  
Natural Environment ◽  
Dominant Role ◽  
Digital Terrain Model ◽  
Binary Trees ◽  
Terrain Model ◽  
Digital Terrain ◽  
The Subject ◽  
The One

Abstract The relationships between individual components of the natural environment have long been an object of research (Kostrowicki, Wójcik, 1972; Rączkowska, Kozłowska, 1994; Kozłowska, Rączkowska, 1996). This paper is an attempt to analyse the relationships between two geocomponents of the natural environment: relief and vegetation, from a perspective contrary to the one currently prevailing in the literature of the subject. This approach assumes that relief, with its dominant role as a component strongly affecting the formation of the remaining factors, can be indicative in character and as such can represent basic factors that help determine and anticipate the occurrences of certain plant communities as well as locations with no vegetation. Using geoinformation data along with the tools to process them, an attempt was made to assess the usefulness of the DTM (Digital Terrain Model) to identify selected plant communities, rock and water. The development of a model of the relationships between the relief and the vegetation is an attempt to capture the correspondence between the parameters characterising the relief, calculated using the DTM model and classes of objects, with the use of information obtained from an Ikonos XS image. This model was subsequently used to draw a map of the land cover for a part of the Gąsienicowa Valley in the High Tatra (Dolina Gąsienicowa). For the purpose of this exercise, a technique of data classification called DBT (Decision Binary Trees) was used.

scholarly journals The Effect of LiDAR Sampling Density on DTM Accuracy for Areas with Heavy Forest Cover

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 265
Author(s):  
Mihnea Cățeanu ◽  
Arcadie Ciubotaru
Keyword(s):  
Forest Cover ◽  
Initial Point ◽  
Ground Surface ◽  
Digital Terrain Model ◽  
Morphological Data ◽  
Sampling Density ◽  
Terrain Model ◽  
Digital Terrain ◽  
Point Density ◽  
The Impact

Laser scanning via LiDAR is a powerful technique for collecting data necessary for Digital Terrain Model (DTM) generation, even in densely forested areas. LiDAR observations located at the ground level can be separated from the initial point cloud and used as input for the generation of a Digital Terrain Model (DTM) via interpolation. This paper proposes a quantitative analysis of the accuracy of DTMs (and derived slope maps) obtained from LiDAR data and is focused on conditions common to most forestry activities (rough, steep terrain with forest cover). Three interpolation algorithms were tested: Inverse Distance Weighted (IDW), Natural Neighbour (NN) and Thin-Plate Spline (TPS). Research was mainly focused on the issue of point data density. To analyze its impact on the quality of ground surface modelling, the density of the filtered data set was artificially lowered (from 0.89 to 0.09 points/m2) by randomly removing point observations in 10% increments. This provides a comprehensive method of evaluating the impact of LiDAR ground point density on DTM accuracy. While the reduction of point density leads to a less accurate DTM in all cases (as expected), the exact pattern varies by algorithm. The accuracy of the LiDAR-derived DTMs is relatively good even when LiDAR sampling density is reduced to 0.40–0.50 points/m2 (50–60 % of the initial point density), as long as a suitable interpolation algorithm is used (as IDW proved to be less resilient to density reductions below approximately 0.60 points/m2). In the case of slope estimation, the pattern is relatively similar, except the difference in accuracy between IDW and the other two algorithms is even more pronounced than in the case of DTM accuracy. Based on this research, we conclude that LiDAR is an adequate method for collecting morphological data necessary for modelling the ground surface, even when the sampling density is significantly reduced.

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