scholarly journals Small Scale Map Projection and Coordinate System Improvement in Consideration of Usability and Compatibility

2016 ◽  
Vol 34 (2) ◽  
pp. 171-183
Author(s):  
Byoung Gil Choi ◽  
Young Woo Na ◽  
Jin Woo Jung
Keyword(s):  
Coordinate System ◽  
Small Scale ◽  
Map Projection ◽  
System Improvement

scholarly journals Improvement of Mountain-Wave Turbulence Forecasts in NOAA’s Rapid Refresh (RAP) Model with the Hybrid Vertical Coordinate System

2019 ◽  
Vol 34 (3) ◽  
pp. 773-780 ◽  
Author(s):  
Jung-Hoon Kim ◽  
Robert D. Sharman ◽  
Stanley G. Benjamin ◽  
John M. Brown ◽  
Sang-Hun Park ◽  
...  
Keyword(s):  
North America ◽  
Coordinate System ◽  
Weather Prediction ◽  
Energy Dissipation Rate ◽  
Small Scale ◽  
False Alarms ◽  
Mountain Wave ◽  
Vertical Coordinate ◽  
Terrain Following ◽  
Scale Turbulence

Abstract Spurious mountain-wave features have been reported as false alarms of light-or-stronger numerical weather prediction (NWP)-based cruise level turbulence forecasts especially over the western mountainous region of North America. To reduce this problem, a hybrid sigma–pressure vertical coordinate system was implemented in NOAA’s operational Rapid Refresh model, version 4 (RAPv4), which has been running in parallel with the conventional terrain-following coordinate system of RAP version 3 (RAPv3). Direct comparison of vertical velocity |w| fields from the RAPv4 and RAPv3 models shows that the new RAPv4 model significantly reduces small-scale spurious vertical velocities induced by the conventional terrain-following coordinate system in the RAPv3. For aircraft-scale turbulence forecasts, |w| and |w|/Richardson number (|w|/Ri) derived from both the RAPv4 and RAPv3 models are converted into energy dissipation rate (EDR) estimates. Then, those EDR-scaled indices are evaluated using more than 1.2 million in situ EDR turbulence reports from commercial aircraft for 4 months (September–December 2017). Scores of the area under receiver operating characteristic curves for the |w|- and |w|/Ri-based EDR forecasts from the RAPv4 are 0.69 and 0.83, which is statistically significantly improved over the RAPv3 of 0.63 and 0.77, respectively. The new RAPv4 became operational on 12 July 2018 and provides better guidance for operational turbulence forecasting over North America.

High-Performance Small-Scale Raster Map Projection Empowered by Cyberinfrastructure

2018 ◽  
pp. 171-188
Author(s):  
Michael P. Finn ◽  
Yan Liu ◽  
David M. Mattli ◽  
Babak Behzad ◽  
Kristina H. Yamamoto ◽  
...  
Keyword(s):  
High Performance ◽  
Small Scale ◽  
Map Projection

scholarly journals Proposed single-zone map projection system for Turkey

2021 ◽  
Vol 112 (1) ◽  
pp. 35-45
Author(s):  
Faruk Yildirim ◽  
Fatih Kadi
Keyword(s):  
Coordinate System ◽  
Large Scale ◽  
Projection System ◽  
Map Projection ◽  
Map Projections ◽  
Coordinate Base ◽  
Processing Errors ◽  
First Time ◽  
East West ◽  
Single Coordinate

Abstract The coordinate base of the maps or sheets produced is the Universal Transversal Mercator (UTM) conformal projection, and it is not possible to work in a single coordinate system in Turkey. Therefore, a transition from UTM to other conformal projections is required. For the countries extending in an east–west UTM zone width like Turkey, composite projection (CP), a double standard paralleling Lambert Conformal Conic (LCC) and double map projections (DP) are used widely. However, this process causes increase in working load and processing errors by users. This study aims to determine a common projection system that can be used in the whole country. In this context, a composite projection from UTM and LCC projection has been defined for the first time. According to the results obtained, map projection CP with the least distortion values in both east–west and north–south directions has been chosen. With the CP selection, a single coordinate system has been determined for medium- and large-scale maps. Projection correction formulas, scale factor and false origin have been determined for map coordinates in CP. These distortions are obtained with a difference of less than 1 cm for 1 km long sides and less than 0.003″ for the azimuth value of this side, when the correction formulas are used.

Statistics of Absolute and Relative Dispersion in the Atmospheric Convective Boundary Layer: A Large-Eddy Simulation Study

2006 ◽  
Vol 63 (4) ◽  
pp. 1253-1272 ◽  
Author(s):  
Alessandro Dosio ◽  
Jordi Vilà-Guerau de Arellano
Keyword(s):  
Coordinate System ◽  
Large Scale ◽  
Relative Concentration ◽  
Small Scale ◽  
Third Order ◽  
Convective Boundary ◽  
The Third ◽  
Eddy Simulation ◽  
The Absolute ◽  
Mean Concentration

Abstract The influence of the different scales of turbulent motion on plume dispersion in the atmospheric convective boundary layer (CBL) is studied by means of a large-eddy simulation (LES). In particular, the large-scale (meandering) and small-scale (relative diffusion) contributions are separated by analyzing dispersion in two reference systems: the absolute (fixed) coordinate system and the coordinate system relative to the plume’s instantaneous center of mass. In the relative coordinate system, the (vertically) inhomogeneous meandering motion is removed, and only the small-scale, homogeneous turbulent motion contributes to the dispersion process. First, mean plume position, dispersion parameters (variance), and skewness of the plume position are discussed. The analysis of the third-order moments shows how the structure and the symmetry of scalar distribution are affected with respect to the turbulent characteristics of the CBL (inhomogeneity of the large-scale vertical motion) and the presence of the boundary conditions (surface and top of the CBL). In fact, the reflection of the plume by the CBL boundaries generates the presence of nonlinear cross-correlation terms in the balance equation for the third-order moments of the plume position. As a result, the third-order moment of the absolute position is not balanced by the sum of the third-order moments of the meandering and relative plume position. Second, mean concentration and concentration fluctuations are calculated and discussed in both coordinate systems. The intensity of relative concentration fluctuation icr, which quantifies the internal (in plume) mixing, is explicitly calculated. Based on these results, a parameterization for the probability distribution function (PDF) of the relative concentration is proposed, showing very good agreement with the LES results. Finally, the validity of Gifford’s formula, which relates the absolute concentration’s high-order moments to the relative concentration and the PDF of the plume centerline, is studied. It is found that due to the presence of the CBL boundaries, Gifford’s formula is not able to reproduce correctly the value of the absolute mean concentration near the ground. This result is analyzed by showing that, when the plume is reflected by the CBL boundaries, the instantaneous relative plume width z′2r(t) departs from its mean value σ2r. By introducing the skewness of the relative plume position into a parameterization for the relative mean concentration, the results for the calculated mean concentration are improved.

An Integrated Approach to Map Projections and Plane Coordinates

1974 ◽  
Vol 28 (5) ◽  
pp. 637-642
Author(s):  
Thomas Wray
Keyword(s):  
Coordinate System ◽  
Traditional Approach ◽  
Integrated Approach ◽  
Integrated System ◽  
Intermediate Step ◽  
Coordinate Systems ◽  
Map Projection ◽  
Map Projections ◽  
The North ◽  
The Individual

A redefinition of the North American geodetic networks may well require a reappraisal of the various plane coordinate systems in use in North America. Now “plane coordinate system” and “map projection” are really only different names for the same thing. An approach to coordinate conversion is described in which each map projection (plane coordinate system) is not analyzed as an individual, but the whole set of map projections is regarded as an integrated system. The various projections are displayed in a “family tree” and conversion between two coordinate systems is performed by following the most direct path in this tree. The advantages of this approach are that 1) reduction to latitude and longitude as an intermediate step is usually unnecessary and 2) the individual steps in the tree are usually quite simple mathematically owing to the flexibility in the parameters used. The traditional approach using latitude and longitude as essential parameters often leads to ugly mathematical functions best approximated by Taylor series whose coefficients may be quite awkward to determine.

scholarly journals Estimation of the Cartographic Projection and~its Application in Geoinformatics-habilitation thesis presentation

2017 ◽  
Vol 16 (1) ◽  
pp. 17-52 ◽  
Author(s):  
Tomáš Bayer
Keyword(s):  
Pole Position ◽  
Distance Functions ◽  
Small Scale ◽  
Central Meridian ◽  
Unknown Parameters ◽  
Map Projection ◽  
Geometric Reconstruction ◽  
Sphere Radius ◽  
Habilitation Thesis ◽  
Map Analysis

<div class="abstract"><div class="abstract_item"><em>Modern techniques for the map analysis allow for the creation of full or partial geometric reconstruction of its content. The projection is described by the set of estimated constant values: transformed pole position, standard parallel latitude, longitude of the central meridian, and a constant parameter. Analogously the analyzed map is represented by its constant values: auxiliary sphere radius, origin shifts, and angle of rotation. Several new methods denoted as M6-M9 for the estimation of an unknown map projection and its parameters differing in the number of determined parameters, reliability, robustness, and convergence have been developed. However, their computational demands are similar. Instead of directly measuring the dissimilarity of two projections, the analyzed map in an unknown projection and the image of the sphere in the well-known (i.e., analyzed) projection are compared. Several distance functions for the similarity measurements based on the location as well as shape similarity approaches are proposed. An unconstrained global optimization problem poorly scaled, with large residuals, for the vector of unknown parameters is solved by the hybrid BFGS method. To avoid a slower convergence rate for small residual problems, it has the ability to switch between first- and second-order methods. Such an analysis is beneficial and interesting for historic, old, or current maps without information about the projection. Its importance is primarily referred to refinement of spatial georeference for the medium- and small-scale maps, analysis of the knowledge about the former world, analysis of the incorrectly/inaccurately drawn regions, and appropriate cataloging of maps. The proposed algorithms have been implemented in the new version of the <span style="font-family: monospace;">detectproj</span> software.</em></div></div>

scholarly journals Given the problem of projection, are heat maps an oxymoron?

2019 ◽  
Vol 1 ◽  
pp. 1-2
Author(s):  
Daniel Strebe
Keyword(s):  
Density Variation ◽  
Two Dimensions ◽  
Small Scale ◽  
Continuous Measure ◽  
Area Measure ◽  
Heat Map ◽  
Heat Maps ◽  
Map Projection ◽  
Map Projections ◽  
Mercator Projection

<p><strong>Abstract.</strong> With the proliferation of data analysis and visualization tools, we see more and more heat maps. But should we? Are such displays meaningful? At large scales, heat maps need not be controversial (though common tools can blight even simple cases). But what about small-scale maps? Is anyone thinking about the effects of projection on heat maps? How do map projections change the semantics of heat maps? What projections permit meaningful heat maps? How should heat maps be calculated in the presence of a map projection? We explore these problems and questions in this presentation to offer critique and advice.</p><p>For the purposes of this discussion, a heat map is a representation of the density or magnitude of a spatial phenomenon on two dimensions, treating the density or magnitude as a continuous measure whether or not the underlying phenomenon is continuous. If the data are too sparse in the presentation space, then the fiction of continuity ought to be avoided; a heat map would not be an appropriate visualization. While real world examples of heat maps that violate this principle are easy to find, we take the principle for granted and do not elaborate further here.</p><p>Unfortunately, there are several other ways to construct ineffective heat maps. One of the primary offenses is to ignore the effect of map projection on the presentation of density. It should be clear that a projection whose area measure varies widely across the presentation space necessarily distorts density. If the heat map is a presentation of density &amp;ndash; which most are &amp;ndash; then poor choice of projection would contradict the purpose of a heat map. The result would be a blatant fiction. Surprisingly, the Mercator projection often can be found in small scale heat maps, for the reason that the projection is common, is the default in many sets of tooling, and is sometimes the only projection available with the set of map construction tools. And yet, as far as density variation goes, a worse case than Mercator cannot be found among common projections.</p><p>Even if density remains constant across the map, a poor heat map could be generated if the analysis for the heat map mixes phenomenon space, which is geographic, with projected space, which is not. Common tools commit this fallacy. The result is that a phenomenon whose density diminishes radially (for example) from a hot point might show as concentric circles of decreasing intensity on the projected map, whereas we would expect elongations of the heat field in accordance with the projection’s distortion metric.</p><p>We conclude that, while it is possible to construct responsible heat maps of geographic data, there are several pitfalls. Among these pitfalls, we find that common tools conspire to assist in the presentation of fiction instead of fact.</p>

scholarly journals A coordinate-system-independent method for comparing joint rotational mobilities

2020 ◽  
Vol 223 (18) ◽  
pp. jeb227108
Author(s):  
Armita R. Manafzadeh ◽  
Stephen M. Gatesy
Keyword(s):  
Coordinate System ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Rotational Mobility ◽  
Coordinate Systems ◽  
Map Projection ◽  
Fold Reduction ◽  
Euler Space ◽  
Rotational Degrees Of Freedom ◽  
Alternative Spaces

ABSTRACTThree-dimensional studies of range of motion currently plot joint poses in a ‘Euler space’ whose axes are angles measured in the joint's three rotational degrees of freedom. Researchers then compute the volume of a pose cloud to measure rotational mobility. However, pairs of poses that are equally different from one another in orientation are not always plotted equally far apart in Euler space. This distortion causes a single joint's mobility to change when measured based on different joint coordinate systems and precludes fair comparison among joints. Here, we present two alternative spaces inspired by a 16th century map projection – cosine-corrected and sine-corrected Euler spaces – that allow coordinate-system-independent comparison of joint rotational mobility. When tested with data from a bird hip joint, cosine-corrected Euler space demonstrated a 10-fold reduction in variation among mobilities measured from three joint coordinate systems. This new quantitative framework enables previously intractable, comparative studies of articular function.

Sign in / Sign up

Export Citation Format

Share Document