scholarly journals Analytical procedures for 3D mapping at the Photogeological Laboratory of the Geological Survey of Denmark and Greenland

2018 ◽  
pp. 99-104 ◽  
Author(s):  
Erik Vest Sørensen ◽  
Mads Dueholm
Keyword(s):  
Three Dimensional ◽  
Three Dimensions ◽  
Geological Survey ◽  
Aerial Photographs ◽  
3D Mapping ◽  
Digital Version ◽  
Remote Sensing Technique ◽  
Small Frame ◽  
Analytical Procedures ◽  
Steep Terrain

Photogrammetry is a classical remote sensing technique dating back to the 19th century that allows geologists to make three-dimensional observations in two-dimensional images using human stereopsis. Pioneering work in the 1980s and 1990s (Dueholm 1992) combined the use of vertical (nadirlooking) aerial photographs with oblique stereo images from handheld small-frame cameras into so-called multi-model photogrammetry. This was a huge technological step forward that made it possible to map, in three dimensions, steep terrain that would otherwise be inaccessible or poorly resolved in conventional nadir-looking imagery. The development was fundamental to the mapping and investigation of e.g. the Nuussuaq basin (Pedersen et al. 2006). Digital photogrammetry, the all-digital version of multi-model photogrammetry, is nowadays an efficient and powerful geological tool that is used by the Photogeological Laboratory at the Geological Survey of Denmark and Greenland (GEUS) to address geological problems in a range of projects from 3D mapping to image-based surface reconstruction and orthophoto production. Here we present an updated description (complementary to Dueholm 1992) of the analytical procedures in the typical digital workflow used in current 3Dmapping projects at GEUS.

MORPHOLOGICAL STUDY OF GEOPHYSICAL MAPS BY VIEWING IN THREE DIMENSIONS

Geophysics ◽  
1971 ◽  
Vol 36 (2) ◽  
pp. 396-414 ◽  
Author(s):  
S. Parker Gay
Keyword(s):  
Optical System ◽  
Morphological Study ◽  
Three Dimensional ◽  
Polarized Light ◽  
Three Dimensions ◽  
Aerial Photographs ◽  
Texture Recognition ◽  
Contour Map ◽  
Contour Maps ◽  
One Step

Stereo pairs of contour maps may be constructed by a process analogous to, but the inverse of, the process used to make contour maps from stereo pairs of aerial photographs. This construction can be carried out either manually or with computer plotting devices. The contoured stereo pairs are then viewed in three dimensions by a variety of methods: with lens or mirror stereoscopes, with bicolor anaglyphs in drafted, printed, or projected form, or by polarized light methods. Preferred techniques at present are 1) 5‐inch wide prints viewed by the mirror stereoscope, and 2) anaglyphic rear projection on a 3×4 ft screen. The advantages of studying complex contour maps in three dimensions are striking. The entire morphology of the map may be studied rapidly by the human optical system, the latter carrying out such functions as trend filtering, wavelength filtering, form and texture recognition, and location of linears almost simultaneously. Important features that are missed or seen with difficulty on the flat contour map become obvious in a three‐dimensional view, and may be studied further in detail by manual or computer techniques. The method appears to be a significant interpretational breakthrough, bringing us one step closer to a total interpretation, wherein all observable map features are correlated with their geological causes.

Cellular Automaton Simulations of Surface Mass Transport Due to Curvature Gradients: Simulations of Sintering in 3-D.

1991 ◽  
Vol 249 ◽  
Author(s):  
D.P. Bentz ◽  
P.J.P. Pimienta ◽  
E.J. Garboczi ◽  
W.C. Carter
Keyword(s):  
Cellular Automaton ◽  
Scaling Laws ◽  
Chemical Potential ◽  
Pore Space ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Computation Method ◽  
Surface Mass ◽  
Digital Version ◽  
The Continuum

ABSTRACTA cellular automaton algorithm is described that simulates the evolution of a surface driven by the reduction of chemical potential differences on the surface. When the surface tension is isotropic, the chemical potential is proportional to the curvature at the surface. This process is important in the development of microstructure during the sintering of powders. The algorithm is implemented in two and three dimensions in a digital image mode, using discrete pixels to represent continuum objects. The heart of the algorithm is a pixel-counting-based method for computing the potential at a pixel located in a digital surface. This method gives an approximate measure of the curvature at the given surface pixel. The continuum version of this method is analytically shown to give the true curvature at a point on a continuum surface. The digital version of the curvature computation method is shown to obey the scaling laws derived for the continuum version. The evolution of the surface of a three dimensional loosely packed powder, along with the percolation characteristics of its pore space, are computed as an example of the algorithm.

scholarly journals A FRAMEWORK FOR RELIABLE THREE-DIMENSIONAL UNDERGROUND UTILITY MAPPING FOR URBAN PLANNING

2018 ◽  
Vol XLII-4/W10 ◽  
pp. 209-214 ◽  
Author(s):  
R. van Son ◽  
S. W. Jaw ◽  
J. Yan ◽  
V. Khoo ◽  
R. Loo ◽  
...  
Keyword(s):  
Urban Planning ◽  
High Speed ◽  
Large Scale ◽  
Three Dimensional ◽  
Research Literature ◽  
Three Dimensions ◽  
3D Mapping ◽  
Literature Study ◽  
Underground Utilities ◽  
Utility Services

<p><strong>Abstract.</strong> To optimise the use of limited available land, land-scarce cities such as Singapore are increasingly looking towards the underground in search of more space. A good understanding of what already exists underground is essential for the planning of underground spaces. In particular, utility services make up a significant part of what exists underground. To meet planning needs, the Singapore government has initiated efforts towards bringing records of existing utility networks together in a single database and share its contents to support planning, design, and construction of underground developments. However, these records can not be relied on to support these critical processes: They are not guaranteed to represent today’s state of the underground, are not accurate or of unknown accuracy, are inconsistently modelled, and may indicate as-design information instead of as-built information. This lack of reliability leads to an increase in cost and a loss in efficiency caused by the need to repeatedly survey to locate existing utility services on-site, and can have potentially disastrous outcomes when an excavation would damage existing services. Technological advances in utility surveying and mapping devices such as Ground Penetrating Radar (GPR) and gyroscopic pipeline mapping devices offer the potential of accurately mapping utilities in three dimensions (3D) at a large scale and high speed. However, a better understanding of the benefits and limitations of these technologies in a practical context is needed, as well as their suitability for mapping to support applications such as urban planning and land administration. The Digital Underground project is a collaboration between Singapore-ETH Centre, Singapore Land Authority and the City of Zürich that aims to develop a roadmap towards a reliable 3D utility map of Singapore. To enable the development of utility mapping standards and guidelines, the 3D mapping workflow for underground utilities is studied extensively based on market research, literature study, and case studies. This work presents the beginnings of a framework for 3D mapping of underground utilities as one of the initial results of the Digital Underground project as it is in progress. From these experiences, it can be concluded that, together with existing data, data captured using various surveying methods can indeed contribute to the establishment and maintenance of a consolidated and reliable utility map. To this end, a multi-sensor, multi-data 3D mapping workflow is proposed to integrate data captured using different surveying techniques during different moments in the development lifecycle of utilities. Based on this framework, this work also identifies areas for improvement and critical gaps to be bridged that will ultimately form part of the roadmap.</p>

Design and modeling of linearly-constrained compliant spines for human-scale locomotion on rocky surfaces

2017 ◽  
Vol 36 (9) ◽  
pp. 985-999 ◽  
Author(s):  
Shiquan Wang ◽  
Hao Jiang ◽  
Mark R Cutkosky
Keyword(s):  
Three Dimensional ◽  
Humanoid Robots ◽  
Normal Direction ◽  
Three Dimensions ◽  
Shear Stresses ◽  
Spine Density ◽  
Human Scale ◽  
Linearly Constrained ◽  
Bending Loads ◽  
Steep Terrain

We present a new spine solution for the locomotion of human-scale robots on steep, rocky surfaces, known as linearly-constrained spines. The spine stiffness is low in the normal direction but high with respect to lateral and bending loads. The solution differs from previous spine arrays used for small robots in having a much higher spine density and less spine scraping over asperities. We present theoretical and empirical results to demonstrate that this solution is capable of shear stresses of over 200kPa, enabling human-scale robots to apply forces parallel to steep rock surfaces for climbing, bracing, etc. The analysis includes the effects of spine geometry, stiffness, backlash and three-dimensional loading angle to predict the overall forces possible in three dimensions of both single and opposed configurations of spine arrays. Demonstrated applications include a gripper for a “smart staff” aimed at helping humanoid robots to negotiate steep terrain and a palm that provides over 700N in shear for the RoboSimian quadruped.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

Extension of the Spatial PDI Model to Three Dimensions

1997 ◽  
Vol 84 (1) ◽  
pp. 176-178
Author(s):  
Frank O'Brien
Keyword(s):  
Population Density ◽  
Dimensional Space ◽  
Finite Lattice ◽  
Three Dimensional ◽  
Upper Bounds ◽  
Three Dimensions ◽  
Lower And Upper Bounds ◽  
Density Index ◽  
Three Dimensional Space

The author's population density index ( PDI) model is extended to three-dimensional distributions. A derived formula is presented that allows for the calculation of the lower and upper bounds of density in three-dimensional space for any finite lattice.

scholarly journals Free partition functions and an averaged holographic duality

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Nima Afkhami-Jeddi ◽  
Henry Cohn ◽  
Thomas Hartman ◽  
Amirhossein Tajdini
Keyword(s):  
Partition Function ◽  
Spectral Gap ◽  
Central Charge ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Partition Functions ◽  
General Constraints ◽  
Dimensional Gravity ◽  
Holographic Duality

Abstract We study the torus partition functions of free bosonic CFTs in two dimensions. Integrating over Narain moduli defines an ensemble-averaged free CFT. We calculate the averaged partition function and show that it can be reinterpreted as a sum over topologies in three dimensions. This result leads us to conjecture that an averaged free CFT in two dimensions is holographically dual to an exotic theory of three-dimensional gravity with U(1)c×U(1)c symmetry and a composite boundary graviton. Additionally, for small central charge c, we obtain general constraints on the spectral gap of free CFTs using the spinning modular bootstrap, construct examples of Narain compactifications with a large gap, and find an analytic bootstrap functional corresponding to a single self-dual boson.

Turbulent three-dimensional dielectric electrohydrodynamic convection between two plates

2012 ◽  
Vol 696 ◽  
pp. 228-262 ◽  
Author(s):  
A. Kourmatzis ◽  
J. S. Shrimpton
Keyword(s):  
Spatial Data ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Energy Budgets ◽  
Turbulent Regime ◽  
Scalar Flux ◽  
Wide Range ◽  
Scalar Variance

AbstractThe fundamental mechanisms responsible for the creation of electrohydrodynamically driven roll structures in free electroconvection between two plates are analysed with reference to traditional Rayleigh–Bénard convection (RBC). Previously available knowledge limited to two dimensions is extended to three-dimensions, and a wide range of electric Reynolds numbers is analysed, extending into a fully inherently three-dimensional turbulent regime. Results reveal that structures appearing in three-dimensional electrohydrodynamics (EHD) are similar to those observed for RBC, and while two-dimensional EHD results bear some similarities with the three-dimensional results there are distinct differences. Analysis of two-point correlations and integral length scales show that full three-dimensional electroconvection is more chaotic than in two dimensions and this is also noted by qualitatively observing the roll structures that arise for both low (${\mathit{Re}}_{E} = 1$) and high electric Reynolds numbers (up to ${\mathit{Re}}_{E} = 120$). Furthermore, calculations of mean profiles and second-order moments along with energy budgets and spectra have examined the validity of neglecting the fluctuating electric field ${ E}_{i}^{\ensuremath{\prime} } $ in the Reynolds-averaged EHD equations and provide insight into the generation and transport mechanisms of turbulent EHD. Spectral and spatial data clearly indicate how fluctuating energy is transferred from electrical to hydrodynamic forms, on moving through the domain away from the charging electrode. It is shown that ${ E}_{i}^{\ensuremath{\prime} } $ is not negligible close to the walls and terms acting as sources and sinks in the turbulent kinetic energy, turbulent scalar flux and turbulent scalar variance equations are examined. Profiles of hydrodynamic terms in the budgets resemble those in the literature for RBC; however there are terms specific to EHD that are significant, indicating that the transfer of energy in EHD is also attributed to further electrodynamic terms and a strong coupling exists between the charge flux and variance, due to the ionic drift term.

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