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24 pages, 7145 KiB  
Article
On the Theoretical Link between Optimized Geospatial Conflation Models for Linear Features
by Zhen Lei, Zhangshun Yuan and Ting L. Lei
ISPRS Int. J. Geo-Inf. 2024, 13(9), 310; https://doi.org/10.3390/ijgi13090310 - 29 Aug 2024
Viewed by 890
Abstract
Geospatial data conflation involves matching and combining two maps to create a new map. It has received increased research attention in recent years due to its wide range of applications in GIS (Geographic Information System) data production and analysis. The map assignment problem [...] Read more.
Geospatial data conflation involves matching and combining two maps to create a new map. It has received increased research attention in recent years due to its wide range of applications in GIS (Geographic Information System) data production and analysis. The map assignment problem (conceptualized in the 1980s) is one of the earliest conflation methods, in which GIS features from two maps are matched by minimizing their total discrepancy or distance. Recently, more flexible optimization models have been proposed. This includes conflation models based on the network flow problem and new models based on Mixed Integer Linear Programming (MILP). A natural question is: how are these models related or different, and how do they compare? In this study, an analytic review of major optimized conflation models in the literature is conducted and the structural linkages between them are identified. Moreover, a MILP model (the base-matching problem) and its bi-matching version are presented as a common basis. Our analysis shows that the assignment problem and all other optimized conflation models in the literature can be viewed or reformulated as variants of the base models. For network-flow based models, proof is presented that the base-matching problem is equivalent to the network-flow based fixed-charge-matching model. The equivalence of the MILP reformulation is also verified experimentally. For the existing MILP-based models, common notation is established and used to demonstrate that they are extensions of the base models in straight-forward ways. The contributions of this study are threefold. Firstly, it helps the analyst to understand the structural commonalities and differences of current conflation models and to choose different models. Secondly, by reformulating the network-flow models (and therefore, all current models) using MILP, the presented work eases the practical application of conflation by leveraging the many off-the-shelf MILP solvers. Thirdly, the base models can serve as a common ground for studying and writing new conflation models by allowing a modular and incremental way of model development. Full article
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<p>The flow network for the fc−matching problem. Adapted from [<a href="#B11-ijgi-13-00310" class="html-bibr">11</a>].</p>
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<p>The flow network for the fc−bimatching problem. Adapted from [<a href="#B11-ijgi-13-00310" class="html-bibr">11</a>].</p>
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<p>Six road datasets in Santa Barbara County, CA: Open Street Map vs. TIGER.</p>
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<p>Sensitivity of the <span class="html-italic">fc-matching</span> model to the fixed cost (Sites 1 and 5).</p>
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<p>The recall for the <span class="html-italic">fc-matching</span> problems and the <span class="html-italic">base-matching</span> problems.</p>
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<p>The recall for the <span class="html-italic">fc-matching</span> problems and the <span class="html-italic">base-matching</span> problems.</p>
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<p>The precision for the <span class="html-italic">fc-matching</span> problems and the <span class="html-italic">base-matching</span> problems.</p>
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20 pages, 13777 KiB  
Article
A Semantic-Spatial Aware Data Conflation Approach for Place Knowledge Graphs
by Lianlian He, Hao Li and Rui Zhang
ISPRS Int. J. Geo-Inf. 2024, 13(4), 106; https://doi.org/10.3390/ijgi13040106 - 22 Mar 2024
Cited by 1 | Viewed by 2160
Abstract
Recent advances in knowledge graphs show great promise to link various data together to provide a semantic network. Place is an important part in the big picture of the knowledge graph since it serves as a powerful glue to link any data to [...] Read more.
Recent advances in knowledge graphs show great promise to link various data together to provide a semantic network. Place is an important part in the big picture of the knowledge graph since it serves as a powerful glue to link any data to its georeference. A key technical challenge in constructing knowledge graphs with location nodes as geographical references is the matching of place entities. Traditional methods typically rely on rule-based matching or machine-learning techniques to determine if two place names refer to the same location. However, these approaches are often limited in the feature selection of places for matching criteria, resulting in imbalanced consideration of spatial and semantic features. Deep feature-based methods such as deep learning methods show great promise for improved place data conflation. This paper introduces a Semantic-Spatial Aware Representation Learning Model (SSARLM) for Place Matching. SSARLM liberates the tedious manual feature extraction step inherent in traditional methods, enabling an end-to-end place entity matching pipeline. Furthermore, we introduce an embedding fusion module designed for the unified encoding of semantic and spatial information. In the experiment, we evaluate the approach to named places from Guangzhou and Shanghai cities in GeoNames, OpenStreetMap (OSM), and Baidu Map. The SSARLM is compared with several classical and commonly used binary classification machine learning models, and the state-of-the-art large language model, GPT-4. The results demonstrate the benefit of pre-trained models in data conflation of named places. Full article
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<p>Process for semantic-spatial aware place knowledge graph construction.</p>
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<p>SSARLM Model Architecture Diagram.</p>
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<p>Three data sources in Guangzhou and Shanghai.</p>
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<p>Statistical results of issues for positive samples.</p>
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<p>SPARQL queries on the PlaceKG. (<b>a</b>) Query a PlaceEntity instance by name. (<b>b</b>) Query matched named places that the PlaceEntity instance derived from. (<b>c</b>) Query strategies used for the place name conflation. (<b>d</b>) Query the location of the PlaceEntity instance.</p>
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14 pages, 13333 KiB  
Article
Highway to the Comfort Zone: History of the Psychrometric Chart
by Eric Teitelbaum, Clayton Miller and Forrest Meggers
Buildings 2023, 13(3), 797; https://doi.org/10.3390/buildings13030797 - 17 Mar 2023
Cited by 5 | Viewed by 6873
Abstract
The psychrometric chart is the most common data visualization technique for the designers of thermal comfort systems worldwide. From its humble roots as means of expressing the characteristics of air in building systems design, the use of the chart has grown to include [...] Read more.
The psychrometric chart is the most common data visualization technique for the designers of thermal comfort systems worldwide. From its humble roots as means of expressing the characteristics of air in building systems design, the use of the chart has grown to include the representation of the zones of human thermal comfort according to both conventional and adaptive models. In this paper, we present an extensive history of this development and the fallacies with representing comfort simply as a box that sometimes moves on the chart. The origins of the link between refrigeration control and comfort control are examined through archival reviews, examining the works of Carrier, Yagoglou, and their contemporaries in the context of modern comfort mischaracterizations. A clearer understanding of the mapping of comfort, control, and climate metrics with psychrometrics is reported, and a critique of the conflation is reported to increase awareness of the limitations of such treatment of these three critical domains. Full article
(This article belongs to the Special Issue Indoor Environment and Thermal Comfort Performance of Buildings)
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<p>Willis Carrier’s first psychrometric chart [<a href="#B1-buildings-13-00797" class="html-bibr">1</a>]. Here, the abscissa is labeled “Dry bulb temperature” and provided in degrees Fahrenheit; the ordinate is “Grains of moisture per lb dry air”.</p>
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<p>Yagoglou and Houghton’s equal temperature framework [<a href="#B5-buildings-13-00797" class="html-bibr">5</a>]. Here, the abscissa is “Dry bulb temperature” and provided in degrees Fahrenheit; the ordinate is “Grains of moisture per lb dry air”.</p>
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<p>Experimental setup, data, and output of a study determining the comfort zone with air velocity introduced as an independent variable [<a href="#B6-buildings-13-00797" class="html-bibr">6</a>].</p>
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<p>Kata thermometer study from 1922 [<a href="#B13-buildings-13-00797" class="html-bibr">13</a>]. Here the abscissa is labeled “Dry bulb temperature, Degrees Fahrenheit”; the ordinate is “Cooling Power of Air in Btu per Square Foot per Hour”.</p>
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<p>Use of psychrometrics throughout comfort, controls, and climate frameworks, combining pure psychrometric representations along the lines of the triangle into applied frameworks at the vertices. Beginning with the “Comfort Control” chart and proceeding clockwise, references for each chart are provided [<a href="#B1-buildings-13-00797" class="html-bibr">1</a>,<a href="#B6-buildings-13-00797" class="html-bibr">6</a>,<a href="#B22-buildings-13-00797" class="html-bibr">22</a>,<a href="#B23-buildings-13-00797" class="html-bibr">23</a>,<a href="#B28-buildings-13-00797" class="html-bibr">28</a>,<a href="#B29-buildings-13-00797" class="html-bibr">29</a>].</p>
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<p>Heat transfer through the human body [<a href="#B42-buildings-13-00797" class="html-bibr">42</a>].</p>
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<p>A standard psychrometric chart for system design [<a href="#B28-buildings-13-00797" class="html-bibr">28</a>].</p>
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<p>Demonstrating two regimes of operative temperature versus air speed calculated using Equation (<a href="#FD1-buildings-13-00797" class="html-disp-formula">1</a>); green represents a regime where <math display="inline"><semantics> <mrow> <msub> <mi>t</mi> <mi>r</mi> </msub> <mo>&gt;</mo> <msub> <mi>t</mi> <mi>a</mi> </msub> </mrow> </semantics></math>, which results in an intuitive relationship where the operative temperature decreases as air speed increases; red represents a regime where <math display="inline"><semantics> <mrow> <msub> <mi>t</mi> <mi>r</mi> </msub> <mo>&lt;</mo> <msub> <mi>t</mi> <mi>a</mi> </msub> </mrow> </semantics></math>, which results in operative temperature increasing as air speed increases. This is counterintuitive since an increase in air speed results in more cooling capacity relative to a human body; however, an increasing operative temperature implies warmer conditions.</p>
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21 pages, 7549 KiB  
Article
Harmonizing Full and Partial Matching in Geospatial Conflation: A Unified Optimization Model
by Ting L. Lei and Zhen Lei
ISPRS Int. J. Geo-Inf. 2022, 11(7), 375; https://doi.org/10.3390/ijgi11070375 - 6 Jul 2022
Cited by 3 | Viewed by 1887
Abstract
Spatial data conflation is aimed at matching and merging objects in two datasets into a more comprehensive one. Starting from the “map assignment problem” in the 1980s, optimized conflation models treat feature matching as a natural optimization problem of minimizing certain metrics, such [...] Read more.
Spatial data conflation is aimed at matching and merging objects in two datasets into a more comprehensive one. Starting from the “map assignment problem” in the 1980s, optimized conflation models treat feature matching as a natural optimization problem of minimizing certain metrics, such as the total discrepancy. One complication in optimized conflation is that heterogeneous datasets can represent geographic features differently. Features can correspond to target features in the other dataset either on a one-to-one basis (forming full matches) or on a many-to-one basis (forming partial matches). Traditional models consider either full matching or partial matches exclusively. This dichotomy has several issues. Firstly, full matching models are limited and cannot capture any partial match. Secondly, partial matching models treat full matches just as partial matches, and they are more prone to admit false matches. Thirdly, existing conflation models may introduce conflicting directional matches. This paper presents a new model that captures both full and partial matches simultaneously. This allows us to impose structural constraints differently on full/partial matches and enforce the consistency between directional matches. Experimental results show that the new model outperforms conventional optimized conflation models in terms of precision (89.2%), while achieving a similar recall (93.2%). Full article
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<p>Conflation issues with OpenStreetMap (green) and TIGER (red) networks in downtown Santa Barbara, CA. Blue arrows represent matches. (<b>a</b>) Spatial offsets defeat spatial joins; (<b>b</b>) full and partial matches in a street block.</p>
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<p>Transitive assignments: (<b>a</b>) transitive assignments in fc-bimatching; (<b>b</b>) removing transitive assignments with u-bimatching.</p>
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<p>Test data at six sites in Santa Barbara County, CA, from OSM (green) and TIGER (red), respectively.</p>
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<p>Precision rates of optimized conflation models for the Santa Barbara dataset (OSM vs. TIGER). (<b>a</b>–<b>f</b>) Results for sites #1 through #6.</p>
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<p>Precision rates of optimized conflation models for the Santa Barbara dataset (OSM vs. TIGER). (<b>a</b>–<b>f</b>) Results for sites #1 through #6.</p>
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<p>Recall rates of optimized conflation models for the Santa Barbara dataset (OSM vs. TIGER). (<b>a</b>–<b>f</b>) Results for sites #1 through #6.</p>
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<p>F-score of optimized conflation models for the Santa Barbara dataset (OSM vs. TIGER). (<b>a</b>–<b>f</b>) Results for sites #1 through #6.</p>
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<p>F-score of optimized conflation models for the Santa Barbara dataset (OSM vs. TIGER). (<b>a</b>–<b>f</b>) Results for sites #1 through #6.</p>
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<p>Percentage of full matches produced by tested optimized conflation models for the Santa Barbara dataset (OSM vs. TIGER). (<b>a</b>–<b>f</b>) Results for sites #1 through #6.</p>
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<p>Percentage of full matches produced by tested optimized conflation models for the Santa Barbara dataset (OSM vs. TIGER). (<b>a</b>–<b>f</b>) Results for sites #1 through #6.</p>
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19 pages, 671 KiB  
Review
The Intellectual Domains of Sustainability Leadership in SMEs
by Jane Boeske and Peter A. Murray
Sustainability 2022, 14(4), 1978; https://doi.org/10.3390/su14041978 - 9 Feb 2022
Cited by 15 | Viewed by 5578
Abstract
The goal of this paper is to review the intertwined range of conceptualizations that have blurred developing leadership knowledge regarding environmental sustainability. An examination of the leadership literature reveals differential descriptions about sustainable, environmental, and sustainability leadership which are increasingly being used to [...] Read more.
The goal of this paper is to review the intertwined range of conceptualizations that have blurred developing leadership knowledge regarding environmental sustainability. An examination of the leadership literature reveals differential descriptions about sustainable, environmental, and sustainability leadership which are increasingly being used to imply what sustainability-focused leaders do, their interactions, their relationships, and how they address sustainable challenges. While extant research supports that leadership is a critical capability to respond and adapt to constant external environmental and economic upheaval in large firms, agreement about the types of leadership practices necessary to achieve positive environmental sustainability and eco-efficient outcomes is less clear in Small and Medium Enterprises (SMEs). To resolve these problems, we synthesize the sustainable, environmental and sustainability leadership literature by (a) reviewing and clarifying these leadership constructs, (b) theoretically unravelling these overlapping concepts, and (c) developing an integrated framework of intellectual capital and sustainability leadership practices. From a theoretical perspective, this paper seeks to make a significant contribution to the scholarly leadership literature by offering several leadership classifications of skills and knowledge relevant to leadership knowledge domains. Given that extant research has conflated many leadership approaches, this paper builds on the theoretical knowledge of the kind of leadership skills required for sustainability leadership. From a practical perspective, we provide SME leaders with knowledge about the types of leadership practices, behaviours, and activities that will enhance sustainable productivity in their firms. The paper is designed to advance a new way of thinking about existing sustainability leadership by presenting an original contribution that alters and reorganizes potential causal maps, that are potentially more valuable. Whilst most of the leadership research involves large firms, we seek to better understand and inform sustainability leadership in SMEs. Full article
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<p>An intellectual capital framework of sustainability leadership in SMEs. Source: Authors.</p>
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17 pages, 743 KiB  
Article
No Preferred Reference Frame at the Foundation of Quantum Mechanics
by William Stuckey, Timothy McDevitt and Michael Silberstein
Entropy 2022, 24(1), 12; https://doi.org/10.3390/e24010012 - 22 Dec 2021
Cited by 8 | Viewed by 7374
Abstract
Quantum information theorists have created axiomatic reconstructions of quantum mechanics (QM) that are very successful at identifying precisely what distinguishes quantum probability theory from classical and more general probability theories in terms of information-theoretic principles. Herein, we show how one such principle, Information [...] Read more.
Quantum information theorists have created axiomatic reconstructions of quantum mechanics (QM) that are very successful at identifying precisely what distinguishes quantum probability theory from classical and more general probability theories in terms of information-theoretic principles. Herein, we show how one such principle, Information Invariance and Continuity, at the foundation of those axiomatic reconstructions, maps to “no preferred reference frame” (NPRF, aka “the relativity principle”) as it pertains to the invariant measurement of Planck’s constant h for Stern-Gerlach (SG) spin measurements. This is in exact analogy to the relativity principle as it pertains to the invariant measurement of the speed of light c at the foundation of special relativity (SR). Essentially, quantum information theorists have extended Einstein’s use of NPRF from the boost invariance of measurements of c to include the SO(3) invariance of measurements of h between different reference frames of mutually complementary spin measurements via the principle of Information Invariance and Continuity. Consequently, the “mystery” of the Bell states is understood to result from conservation per Information Invariance and Continuity between different reference frames of mutually complementary qubit measurements, and this maps to conservation per NPRF in spacetime. If one falsely conflates the relativity principle with the classical theory of SR, then it may seem impossible that the relativity principle resides at the foundation of non-relativisitic QM. In fact, there is nothing inherently classical or quantum about NPRF. Thus, the axiomatic reconstructions of QM have succeeded in producing a principle account of QM that reveals as much about Nature as the postulates of SR. Full article
(This article belongs to the Special Issue Quantum Mechanics and Its Foundations II)
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Graphical abstract
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<p>Probability state space for the qubit <math display="inline"><semantics> <mrow> <mo stretchy="false">|</mo> <mi>u</mi> <mo>〉</mo> </mrow> </semantics></math> in the <span class="html-italic">z</span> basis. Since this state space is isomorphic to 3-dimensional real space, the Bloch sphere is shown in a real space reference frame with its related Stern-Gerlach (SG) magnet orientations (see Knight ([<a href="#B59-entropy-24-00012" class="html-bibr">59</a>], p. 1307) for an explanation of the SG experiment). The probability is given for a <math display="inline"><semantics> <mrow> <mo>+</mo> <mn>1</mn> </mrow> </semantics></math> outcome at the measurement direction shown [<a href="#B55-entropy-24-00012" class="html-bibr">55</a>]. Compare this with <a href="#entropy-24-00012-f002" class="html-fig">Figure 2</a>.</p>
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<p>In this set up, the first SG magnets (oriented at <math display="inline"><semantics> <mover accent="true"> <mi>z</mi> <mo>^</mo> </mover> </semantics></math>) are being used to produce an initial state <math display="inline"><semantics> <mrow> <mo stretchy="false">|</mo> <mi>ψ</mi> <mo>〉</mo> <mo>=</mo> <mo stretchy="false">|</mo> <mi>u</mi> <mo>〉</mo> </mrow> </semantics></math> for measurement by the second SG magnets (oriented at <math display="inline"><semantics> <mover accent="true"> <mi>b</mi> <mo>^</mo> </mover> </semantics></math>). Compare this with <a href="#entropy-24-00012-f001" class="html-fig">Figure 1</a>.</p>
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<p>Probability state space for the classical bit.</p>
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<p>The classical constructive model of the Stern-Gerlach (SG) experiment. If the atoms enter with random orientations of their “intrinsic” magnetic moments (due to their “intrinsic” angular momenta), the SG magnets should produce all possible deflections, not just the two that are observed [<a href="#B59-entropy-24-00012" class="html-bibr">59</a>,<a href="#B66-entropy-24-00012" class="html-bibr">66</a>].</p>
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<p>The “intrinsic” angular momentum of Bob’s particle <math display="inline"><semantics> <mover accent="true"> <mi>S</mi> <mo>→</mo> </mover> </semantics></math> projected along his measurement direction <math display="inline"><semantics> <mover accent="true"> <mi>b</mi> <mo>^</mo> </mover> </semantics></math>. This does <span class="html-italic">not</span> happen with spin angular momentum due to NPRF.</p>
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<p>State space for a qubit showing two reference frames of mutually complementary SG spin measurements [<a href="#B55-entropy-24-00012" class="html-bibr">55</a>].</p>
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23 pages, 3092 KiB  
Article
An End-to-End Point of Interest (POI) Conflation Framework
by Raymond Low, Zeynep Duygu Tekler and Lynette Cheah
ISPRS Int. J. Geo-Inf. 2021, 10(11), 779; https://doi.org/10.3390/ijgi10110779 - 15 Nov 2021
Cited by 30 | Viewed by 3841
Abstract
Point of interest (POI) data serves as a valuable source of semantic information for places of interest and has many geospatial applications in real estate, transportation, and urban planning. With the availability of different data sources, POI conflation serves as a valuable technique [...] Read more.
Point of interest (POI) data serves as a valuable source of semantic information for places of interest and has many geospatial applications in real estate, transportation, and urban planning. With the availability of different data sources, POI conflation serves as a valuable technique for enriching data quality and coverage by merging the POI data from multiple sources. This study proposes a novel end-to-end POI conflation framework consisting of six steps, starting with data procurement, schema standardisation, taxonomy mapping, POI matching, POI unification, and data verification. The feasibility of the proposed framework was demonstrated in a case study conducted in the eastern region of Singapore, where the POI data from five data sources was conflated to form a unified POI dataset. Based on the evaluation conducted, the resulting unified dataset was found to be more comprehensive and complete than any of the five POI data sources alone. Furthermore, the proposed approach for identifying POI matches between different data sources outperformed all baseline approaches with a matching accuracy of 97.6% with an average run time below 3 min when matching over 12,000 POIs to result in 8699 unique POIs, thereby demonstrating the framework’s scalability for large scale implementation in dense urban contexts. Full article
(This article belongs to the Special Issue Intelligent Systems Based on Open and Crowdsourced Location Data)
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<p>Overview of the proposed POI conflation framework.</p>
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<p>The data procurement step begins by defining the dimensions of a rectangular bounding box that envelopes the study area before dividing the bounding box into a grid pattern consisting of sub-bounding boxes. The study area’s shapefile is subsequently used to filter out all sub-bounding boxes that do not lie within its boundaries.</p>
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<p>The variable bounding box approach starts by dividing the study area into a series of sub-bounding boxes of a certain dimension and recursively dividing each sub-bounding box into boxes of smaller dimensions each time the number of results returned reaches the upper limit. The number in each circle represents the sequence in which an example query was constructed and called. The red circle indicates that the number of results returned reaches the upper limit, while a green circle indicates that the number of results returned falls below the upper limit.</p>
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<p>An example POI from Google Places before and after the schema standardisation step. A dummy example is provided for illustration.</p>
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<p>Application of the proposed POI conflation framework within the study area of Tampines. POIs obtained from Google Places are not required to go through the Taxonomy Mapping step as the Google Places’ place type taxonomy was chosen as the default taxonomy in this study.</p>
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<p>The geographical distribution of the POIs from different data sources.</p>
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13 pages, 287 KiB  
Review
The Significance of ‘the Person’ in Addiction
by Pádraic Mark Hurley
Religions 2021, 12(10), 893; https://doi.org/10.3390/rel12100893 - 18 Oct 2021
Viewed by 2822
Abstract
Van Gordon et al. outline the classification of their Ontological Addiction Theory (OAT), including its aetiology and treatment. In this review article I will from an appreciative perspective question some of its fundamental assumptions by presenting an alternative view on the ontology of [...] Read more.
Van Gordon et al. outline the classification of their Ontological Addiction Theory (OAT), including its aetiology and treatment. In this review article I will from an appreciative perspective question some of its fundamental assumptions by presenting an alternative view on the ontology of ‘the person’, as distinct from its presently assumed conventional conflation with a contracted separate egoic self. I will propose this view as structurally and ethically significant for the ‘embodied’ experience of a reconstructed “dynamic and non-dual self”, as cultivated in their treatment. Rather than this reconstructed self simply being socially desirable for functional purposes, I will underscore the meaning-generative case for ontological status, in the absence of which, a pervasive ‘sense of lack’ is evident, with all attendant individual, psychological, social, ecological and ethical implications. This article brings a developmental psychology perspective to bear in appreciating ‘personhood’ as an emergent, progressively realised and is thus similarly aligned with the intent of OAT in overcoming egoic addictive suffering. This mapping of the territory however populates a blind spot in OAT’s diagnosis by affirming unique personhood, a quality of ‘integrative presence’, meaningfully understood as a psycho-spiritual ontological reality. It offers, as with OAT’s stated intent, the merit of avoiding attendant mental health and developmental pitfalls, which can beset what we may discern as an implicit transcendental reductionist assumption operative in OAT, where ‘the many’ are reduced to ‘the One’ and there are, it is assumed, no real many. This framing is resonant with the lived experience of healthy ‘individuation’, a process distinct from the problematic phenomenon of ‘individualism’, evidenced by the empirical data on post-conventional human development, which potentially provides diagnostic markers for any optimal treatment discernment. It is also attuned to what many recognise as a contemporary Fourth Turning in Buddhism, in its conscious evolutionary recognition of the emergence in non-dual states of a ‘unique personal perspective’, and/or a relative individuation within the whole. This differentiation has formerly been interpreted through an ‘impersonal’ lens as an egoic holdover, and potentially inhibits ethical action in the world, as distinct from the ethical import and potential fruits stemming from the ontological affirmation of the person. Full article
(This article belongs to the Special Issue Spirituality and Addiction)
40 pages, 21218 KiB  
Article
Automated Conflation of Digital Elevation Model with Reference Hydrographic Lines
by Timofey E. Samsonov
ISPRS Int. J. Geo-Inf. 2020, 9(5), 334; https://doi.org/10.3390/ijgi9050334 - 20 May 2020
Cited by 8 | Viewed by 7251
Abstract
Combining misaligned spatial data from different sources complicates spatial analysis and creation of maps. Conflation is a process that solves the misalignment problem through spatial adjustment or attribute transfer between similar features in two datasets. Even though a combination of digital elevation model [...] Read more.
Combining misaligned spatial data from different sources complicates spatial analysis and creation of maps. Conflation is a process that solves the misalignment problem through spatial adjustment or attribute transfer between similar features in two datasets. Even though a combination of digital elevation model (DEM) and vector hydrographic lines is a common practice in spatial analysis and mapping, no method for automated conflation between these spatial data types has been developed so far. The problem of DEM and hydrography misalignment arises not only in map compilation, but also during the production of generalized datasets. There is a lack of automated solutions which can ensure that the drainage network represented in the surface of generalized DEM is spatially adjusted with independently generalized vector hydrography. We propose a new method that performs the conflation of DEM with linear hydrographic data and is embeddable into DEM generalization process. Given a set of reference hydrographic lines, our method automatically recognizes the most similar paths on DEM surface called counterpart streams. The elevation data extracted from DEM is then rubbersheeted locally using the links between counterpart streams and reference lines, and the conflated DEM is reconstructed from the rubbersheeted elevation data. The algorithm developed for extraction of counterpart streams ensures that the resulting set of lines comprises the network similar to the network of ordered reference lines. We also show how our approach can be seamlessly integrated into a TIN-based structural DEM generalization process with spatial adjustment to pre-generalized hydrographic lines as additional requirement. The combination of the GEBCO_2019 DEM and the Natural Earth 10M vector dataset is used to illustrate the effectiveness of DEM conflation both in map compilation and map generalization workflows. Resulting maps are geographically correct and are aesthetically more pleasing in comparison to a straightforward combination of misaligned DEM and hydrographic lines without conflation. Full article
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<p>Misalignment between digital elevation model and hydrographic line.</p>
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<p>DEM conflation method at a glance: (<b>a</b>) input DEM and hydrographic lines, (<b>b</b>) ordering of hydrographic lines, (<b>c</b>) extraction of counterpart streams, (<b>d</b>) generation of rubbersheet links, (<b>e</b>) extraction of vector elevation data, (<b>f</b>) rubbersheeting of elevation data, (<b>g</b>) triangulation of rubbersheeted elevation data, (<b>h</b>) reconstruction of output conflated DEM. Reference hydrographic lines are depicted in light blue color. Counterpart streams are depicted in red color.</p>
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<p>Reference hydrographic lines split at intersections. Non-standard configurations: (<b>a</b>) braided streams and deltas, (<b>b</b>) incorrect direction of the line, (<b>c</b>) artificial channel connecting two rivers.</p>
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<p>Reference hydrographic lines arranged according to the modified Hack ordering.</p>
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<p>Definition of counterpart stream candidate: reference hydrographic line (<span class="html-italic">h</span>), counterpart stream candidate (<span class="html-italic">s</span>), catch radius (<span class="html-italic">r</span>), Directed Hausdorff distance (<math display="inline"><semantics> <msub> <mover accent="true"> <mi>d</mi> <mo stretchy="false">→</mo> </mover> <mi>H</mi> </msub> </semantics></math>) from <span class="html-italic">s</span> to <span class="html-italic">h</span>.</p>
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<p>Flowline counterpart stream.</p>
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<p>Least-cost counterpart stream. The rectangle outlines the area represented in Figure 9.</p>
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<p>Topological rules for tracing the counterparts of multiple reference hydrographic lines: (<b>a</b>) topological rule 1 (preservation of confluence junction), (<b>b</b>) topological rule 2 (preservation of bifurcation junction), (<b>c</b>) topological rule 3 (extension of subordinate counterpart), (<b>d</b>) topological rule 4 (trimming of subordinate counterpart near confluence junction) (<b>e</b>) topological rule 5 (trimming of subordinate counterpart near bifurcation junction).</p>
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<p>Derivation of counterpart confluence junction.</p>
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<p>Rubbersheet links.</p>
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<p>Conflation of raster DEM with reference hydrographic line: (<b>a</b>) source DEM and reference hydrographic line; (<b>b</b>) elevation points (black dots), counterpart stream (red line), rubbersheet links (white arrows), conflation area (transparent gray polygon) and identity links (white dots); (<b>c</b>) rubbersheeted elevation points; (<b>d</b>) TIN; (<b>e</b>) rasterized conflated DEM; (<b>f</b>) carved and widened conflated DEM.</p>
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<p>Conflation of raster DEM with reference hydrographic line (during generalization): (<b>a</b>) source DEM and reference hydrographic line; (<b>b</b>) streams (black lines), watershed boundaries (gray lines), counterpart stream (red line), rubbersheet links (white arrows), conflation area (transparent gray polygon) and identity links (white dots); (<b>c</b>) rubbersheeted streams and watershed boundaries; (<b>d</b>) TIN; (<b>e</b>) rasterized conflated DEM; (<b>f</b>) carved and widened conflated DEM.</p>
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<p>General workflow for conflation of raster DEM with reference hydrographic lines.</p>
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<p>Top: reference hydrographic lines and generalized conflated DEM. Bottom: counterpart streams and the source DEM.</p>
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<p>Cartographic images for I. Linz (<b>left</b>) and II. Prague (<b>right</b>) fragments: (<b>a</b>) source DEM, (<b>b</b>) conflated DEM, (<b>c</b>) conflated generalized DEM.</p>
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<p>Cartographic images for III. Bratislava (<b>left</b>) and IV. Budapest (<b>right</b>) fragments: (<b>a</b>) source DEM, (<b>b</b>) conflated DEM, (<b>c</b>) conflated generalized DEM.</p>
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<p>Processing time: (<b>a</b>) total processing time and its structure, (<b>b</b>) flowline counterpart tracing time for the reference line with <math display="inline"><semantics> <mrow> <mi>I</mi> <mi>D</mi> <mo>=</mo> <mn>13</mn> </mrow> </semantics></math> as a function of catch radius <span class="html-italic">r</span>.</p>
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<p>Displacement statistics: (<b>a</b>) probability density of rubbersheet link coordinates, (<b>b</b>) probability density of displacement vector horizontal coordinates, (<b>c</b>) empirical distribution function of horizontal displacement magnitude, (<b>d</b>) probability density of vertical displacement, (<b>e</b>) empirical distribution function of the absolute value of vertical displacement.</p>
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<p>Unreliable least-cost counterpart in meandering river section: reference hydrographic line (<span class="html-italic">h</span>), counterpart stream (<span class="html-italic">c</span>).</p>
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5 pages, 351 KiB  
Proceeding Paper
Local Mathematics and No Information at a Distance; Some Effects on Physics and Geometry
by Paul Benioff
Proceedings 2020, 47(1), 3; https://doi.org/10.3390/proceedings2020047003 - 19 May 2020
Viewed by 1341
Abstract
Local mathematics consists of a collection of mathematical systems located at each space and time point. The collection is limited to the systems that include numbers in their axiomatic description. A scalar map between systems at different locations is based on the distinction [...] Read more.
Local mathematics consists of a collection of mathematical systems located at each space and time point. The collection is limited to the systems that include numbers in their axiomatic description. A scalar map between systems at different locations is based on the distinction of two conflated concepts, number and number value. The effect that this setup has on theory descriptions of physical and geometric systems is described. This includes a scalar spin 0 field in gauge theories, expectation values in quantum mechanics and path lengths in geometry. The possible relation of the scalar map to consciousness is noted. Full article
(This article belongs to the Proceedings of IS4SI 2019 Summit)
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<p>Illustration of the existence of local mathematics at each point in space and time. The illustration is for three locations, <math display="inline"> <semantics> <mrow> <mi>x</mi> <mo>,</mo> <mi>t</mi> </mrow> </semantics> </math>, <math display="inline"> <semantics> <mrow> <mi>y</mi> <mo>,</mo> <mi>s</mi> </mrow> </semantics> </math>, and <math display="inline"> <semantics> <mrow> <mi>w</mi> <mo>,</mo> <mi>u</mi> <mo>.</mo> </mrow> </semantics> </math></p>
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19 pages, 33327 KiB  
Article
A New, Score-Based Multi-Stage Matching Approach for Road Network Conflation in Different Road Patterns
by Müslüm Hacar and Türkay Gökgöz
ISPRS Int. J. Geo-Inf. 2019, 8(2), 81; https://doi.org/10.3390/ijgi8020081 - 13 Feb 2019
Cited by 11 | Viewed by 4251
Abstract
Road-matching processes establish links between multi-sourced road lines representing the same entities in the real world. Several road-matching methods have been developed in the last three decades. The main issue related to this process is selecting the most appropriate method. This selection depends [...] Read more.
Road-matching processes establish links between multi-sourced road lines representing the same entities in the real world. Several road-matching methods have been developed in the last three decades. The main issue related to this process is selecting the most appropriate method. This selection depends on the data and requires a pre-process (i.e., accuracy assessment). This paper presents a new matching method for roads composed of different patterns. The proposed method matches road lines incrementally (i.e., from the most similar matching to the least similar). In the experimental testing, three road networks in Istanbul, Turkey, which are composed of tree, cellular, and hybrid patterns, provided by the municipality (authority), OpenStreetMap (volunteered), TomTom (private), and Basarsoft (private) were used. The similarity scores were determined using Hausdorff distance, orientation, sinuosity, mean perpendicular distance, mean length of triangle edges, and modified degree of connectivity. While the first four stages determined certain matches with regards to the scores, the last stage determined them with a criterion for overlapping areas among the buffers of the candidates. The results were evaluated with manual matching. According to the precision, recall, and F-value, the proposed method gives satisfactory results on different types of road patterns. Full article
(This article belongs to the Special Issue Multi-Source Geoinformation Fusion)
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<p>Study area and road networks composed of tree (<b>a</b>), cellular (<b>b</b>), and hybrid (<b>c</b>) patterns.</p>
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<p>Two candidates for matching (<b>a</b>), minimum distances from Line r to Line g (<b>b</b>), from Line g to Line r (<b>c</b>), and maximum of minimum distances (i.e., Hausdorff distance) (<b>d</b>).</p>
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<p>Orientation angles, intervals, and classes.</p>
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<p>The sinuous length (S) and the straight-line distance (d) of a road line.</p>
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<p>A road line (continuous) and its perpendicular distances (dashed).</p>
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<p>Centroids of road lines and triangulated irregular network (TIN) (dashed lines).</p>
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<p>Degree (<b>a</b>) and modified degree (<b>b</b>) of connectivity of road lines.</p>
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<p>Scoring based on the similarity of the candidate matches.</p>
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<p>Workflow of the proposed method.</p>
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<p>Workflow of the proposed method.</p>
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<p>Accuracy distribution of similarity indicators.</p>
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<p>Alignment by rubber-sheet transformation.</p>
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<p>A sample for the mismatches: Istanbul Metropolitan Municipality (IMM)(green) and Basarsoft (red).</p>
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<p>A sample for the incorrect matches: OSM (blue) and TomTom (orange).</p>
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<p>OpenStreetMap (OSM) (blue) and TomTom (orange) road lines and the sample extends (red rectangles).</p>
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14 pages, 4078 KiB  
Article
Automated Matching of Multi-Scale Building Data Based on Relaxation Labelling and Pattern Combinations
by Yunfei Zhang, Jincai Huang, Min Deng, Chi Chen, Fangbin Zhou, Shuchun Xie and Xiaoliang Fang
ISPRS Int. J. Geo-Inf. 2019, 8(1), 38; https://doi.org/10.3390/ijgi8010038 - 16 Jan 2019
Cited by 11 | Viewed by 4062
Abstract
With the increasingly urgent demand for map conflation and timely data updating, data matching has become a crucial issue in big data and the GIS community. However, non-rigid deviation, shape homogenization, and uncertain scale differences occur in crowdsourced and official building data, causing [...] Read more.
With the increasingly urgent demand for map conflation and timely data updating, data matching has become a crucial issue in big data and the GIS community. However, non-rigid deviation, shape homogenization, and uncertain scale differences occur in crowdsourced and official building data, causing challenges in conflating heterogeneous building datasets from different sources and scales. This paper thus proposes an automated building data matching method based on relaxation labelling and pattern combinations. The proposed method first detects all possible matching objects and pattern combinations to create a matching table, and calculates four geo-similarities for each candidate-matching pair to initialize a probabilistic matching matrix. After that, the contextual information of neighboring candidate-matching pairs is explored to heuristically amend the geo-similarity-based matching matrix for achieving a contextual matching consistency. Three case studies are conducted to illustrate that the proposed method obtains high matching accuracies and correctly identifies various 1:1, 1:M, and M:N matching. This indicates the pattern-level relaxation labelling matching method can efficiently overcome the problems of shape homogeneity and non-rigid deviation, and meanwhile has weak sensitivity to uncertain scale differences, providing a functional solution for conflating crowdsourced and official building data. Full article
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<p>Complex difficulties in matching multi-scale building polygons: (<b>a</b>) shape homogenization and non-rigid deviations between building features; (<b>b</b>) 1:M and M:N matching caused by inconsistent levels of detail (LODs).</p>
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<p>The relaxation labelling matching model in consideration of individual objects and pattern combinations: (<b>a</b>) graphical representation; (<b>b</b>) matrix representation.</p>
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<p>The possible matching combinations of one building object <span class="html-italic">r<sub>i</sub></span>: (<b>a</b>) one building object <span class="html-italic">r<sub>i</sub></span> and its candidate-matching objects <span class="html-italic">t</span><sub>1</sub>…<span class="html-italic">t</span><sub>4</sub>; (<b>b</b>) <span class="html-italic">r<sub>i</sub></span> matching with none; (<b>c</b>) <span class="html-italic">r<sub>i</sub></span> matching with one object; (<b>d</b>) <span class="html-italic">r<sub>i</sub></span> matching with two objects; (<b>e</b>) <span class="html-italic">r<sub>i</sub></span> matching with three objects; (<b>f</b>) <span class="html-italic">r<sub>i</sub></span> matching with four objects.</p>
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<p>Aggregating neighboring candidate-matching objects into pattern combinations: (<b>a</b>) aggregating two or more objects based on centroid distances; (<b>b</b>) aggregating two objects based on convex hull approximation.</p>
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<p>Calculation of absolute geometric similarity and the relative compatibility coefficient: (<b>a</b>) absolute geometric similarity between candidate-matching pairs; (<b>b</b>) relative compatibility coefficient between neighboring candidate-matching pairs. MER: minimum enclosing rectangle.</p>
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<p>Integrating the sub-support indexes of neighboring individual objects and pattern combinations into a total support index: (<b>a</b>) neighboring individual objects and pattern combinations of (<span class="html-italic">r<sub>i</sub></span>, <span class="html-italic">t<sub>j</sub></span>); (<b>b</b>) integrating all sub-support indexes into a total support index.</p>
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<p>Matching results comparison of the mock building data: (<b>a</b>) the initial matching pairs based on local geometric similarity; (<b>b</b>) the identified matching pairs by the object-level relaxation labelling method; (<b>c</b>) the identified matching pairs by the pattern-level relaxation labelling method.</p>
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<p>Matching results of the Xi’an and Dallas data: (<b>a</b>) the matching results for the Xi’an data with obvious scale differences; (<b>b</b>) the matching results for the Dallas data with uncertain scale differences.</p>
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<p>Matching probability change during the relaxation labelling process: (<b>a</b>) probability change of candidate-matching pairs of object #125; (<b>b</b>) probability change of candidate-matching pairs of object #26.</p>
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<p>Comparing the probabilities of matching with an individual object and simultaneously matching with multiple objects: (<b>a</b>) object #81 and #17 in <span class="html-italic">R</span> and their candidate-matching objects in <span class="html-italic">T</span>; (<b>b</b>) the matching probability comparison of all candidate-matching pairs of #81; (<b>c</b>) the matching probability comparison of all candidate-matching pairs of #17.</p>
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17 pages, 2687 KiB  
Article
Graph-Based Matching of Points-of-Interest from Collaborative Geo-Datasets
by Tessio Novack, Robin Peters and Alexander Zipf
ISPRS Int. J. Geo-Inf. 2018, 7(3), 117; https://doi.org/10.3390/ijgi7030117 - 15 Mar 2018
Cited by 26 | Viewed by 7172
Abstract
Several geospatial studies and applications require comprehensive semantic information from points-of-interest (POIs). However, this information is frequently dispersed across different collaborative mapping platforms. Surprisingly, there is still a research gap on the conflation of POIs from this type of geo-dataset. In this paper, [...] Read more.
Several geospatial studies and applications require comprehensive semantic information from points-of-interest (POIs). However, this information is frequently dispersed across different collaborative mapping platforms. Surprisingly, there is still a research gap on the conflation of POIs from this type of geo-dataset. In this paper, we focus on the matching aspect of POI data conflation by proposing two matching strategies based on a graph whose nodes represent POIs and edges represent matching possibilities. We demonstrate how the graph is used for (1) dynamically defining the weights of the different POI similarity measures we consider; (2) tackling the issue that POIs should be left unmatched when they do not have a corresponding POI on the other dataset and (3) detecting multiple POIs from the same place in the same dataset and jointly matching these to the corresponding POI(s) from the other dataset. The strategies we propose do not require the collection of training samples or extensive parameter tuning. They were statistically compared with a “naive”, though commonly applied, matching approach considering POIs collected from OpenStreetMap and Foursquare from the city of London (England). In our experiments, we sequentially included each of our methodological suggestions in the matching procedure and each of them led to an increase in the accuracy in comparison to the previous results. Our best matching result achieved an overall accuracy of 91%, which is more than 10% higher than the accuracy achieved by the baseline method. Full article
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<p>(<b>a</b>) A hypothetical graph. Nodes represent POI and edges matching pair candidates; (<b>b</b>) Matching result obtained with the Naïve method; (<b>c</b>) Matching result obtained with the Best-best method; (<b>d</b>) Matching result obtained with the Combinatorial method.</p>
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<p>Graph representing four existing POIs from OSM and Foursquare. (<b>a</b>–<b>c</b>) Matching results obtained with the three different strategies investigated in this work. Edge weights were computed with the name similarity measure presented in <a href="#sec2dot1-ijgi-07-00117" class="html-sec">Section 2.1</a>.</p>
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<p>Transformation applied to the graph’s edges weights before applying the Combinatorial matching strategy. (<b>a</b>) The graph and its original edge weights; (<b>b</b>) Mean values of the edges connected to each node; (<b>c</b>) Original edge weights minus the mean values computed in the previous step; (<b>d</b>) New edge weights resulting from the summation of the values obtained in the previous step.</p>
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<p>Queries applied for including edges in the subset of edges extracted by the Best-best method. (<b>a</b>) Queries and decision applied to the ambiguous edges obtained by applying the Naïve method taking the blue dataset as the reference one; (<b>b</b>) Queries and decision applied to the ambiguous edges obtained by applying the Naïve method taking the orange dataset as the reference one.</p>
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<p>Queries applied for including edges in the subset of edges extracted by the Best-best method. (<b>a</b>) Queries and decision applied to the ambiguous edges obtained by applying the Naïve method taking the blue dataset as the reference one; (<b>b</b>) Queries and decision applied to the ambiguous edges obtained by applying the Naïve method taking the orange dataset as the reference one.</p>
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<p>Histogram of the distances between the pairs of matching POI from OSM and Foursquare comprising our test-sample set.</p>
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<p>Evaluation of the different matching strategies applied with different similarity measures aggregated by their unweighted and weighted sum. (<b>a</b>,<b>b</b>) One-to-one and one-to-many matching accuracies obtained with the three different strategies and similarity measures aggregated by their unweighted (<b>a</b>) and weighted sum (<b>b</b>). (<b>c</b>,<b>d</b>) One-to-none matching accuracies obtained with the Best-best and Combinatorial strategies and similarity measures aggregated by their unweighted (<b>c</b>) and weighted sum (<b>d</b>). (<b>e</b>,<b>f</b>) Overall accuracies with similarity measures aggregated by their unweighted (<b>e</b>) and weighted sums (<b>f</b>).</p>
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<p>Matching accuracies obtained before and after applying the procedure for tackling the existence of multiple POIs representing the same place.</p>
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12543 KiB  
Article
Texture-Cognition-Based 3D Building Model Generalization
by Po Liu, Chengming Li and Fei Li
ISPRS Int. J. Geo-Inf. 2017, 6(9), 260; https://doi.org/10.3390/ijgi6090260 - 23 Aug 2017
Cited by 4 | Viewed by 5077
Abstract
Three-dimensional (3D) building models have been widely used in the fields of urban planning, navigation and virtual geographic environments. These models incorporate many details to address the complexities of urban environments. Level-of-detail (LOD) technology is commonly used to model progressive transmission and visualization. [...] Read more.
Three-dimensional (3D) building models have been widely used in the fields of urban planning, navigation and virtual geographic environments. These models incorporate many details to address the complexities of urban environments. Level-of-detail (LOD) technology is commonly used to model progressive transmission and visualization. These detailed groups of models can be replaced by a single model using generalization. In this paper, the texture features are first introduced into the generalization process, and a self-organizing mapping (SOM)-based algorithm is used for texture classification. In addition, a new cognition-based hierarchical algorithm is proposed for model-group clustering. First, a constrained Delaunay triangulation (CDT) is constructed using the footprints of building models that are segmented by a road network, and a preliminary proximity graph is extracted from the CDT by visibility analysis. Second, the graph is further segmented by the texture–feature and landmark models. Third, a minimum support tree (MST) is created from the segmented graph, and the final groups are obtained by linear detection and discrete-model conflation. Finally, these groups are conflated using small-triangle removal while preserving the original textures. The experimental results demonstrate the effectiveness of this algorithm. Full article
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<p>Algorithm framework.</p>
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<p>Experimental data: (<b>a</b>) original model-visualization effect with footprints; (<b>b</b>) texture image of the selected model.</p>
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<p>Delaunay triangulation: (<b>a</b>) non-constraint; (<b>b</b>) boundary constraint.</p>
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<p>Visibility analysis: (<b>a</b>) Delaunay triangulation (DT); (<b>b</b>) constrained Delaunay triangulation (CDT); (<b>c</b>) preliminary proximity graph.</p>
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<p>Texture mapping: (<b>a</b>) original triangle; (<b>b</b>) texture image; (<b>c</b>) pixel in the triangles.</p>
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<p>Texture features.</p>
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<p>Texture classification by statistical analysis.</p>
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<p>Texture classification in the (<b>a</b>) global region and (<b>b</b>) local region.</p>
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<p>Proximity graph that is segmented by the types of textures.</p>
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<p>Landmark detection: (<b>a</b>) proximity relationship; (<b>b</b>) graph from landmark detection.</p>
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<p>Minimum support tree (MST).</p>
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<p>Linear detection: (<b>a</b>) preliminary proximity graph; (<b>b</b>) MST; (<b>c</b>) final graph.</p>
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<p>Discrete-model clustering: (<b>a</b>) discrete-polygon linking; (<b>b</b>) the final proximity graph.</p>
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<p>Visualization of model conflation: (<b>a</b>) conflation model; (<b>b</b>) original model.</p>
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<p>Model organization: (<b>a</b>) model’s footprints; (<b>b</b>) clustering order.</p>
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<p>Level of detail (LOD) switch with pixel threshold.</p>
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<p>Model visualization from the (<b>a</b>) far viewpoint; (<b>b</b>) medium viewpoint; and (<b>c</b>) near viewpoint.</p>
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<p>Three-dimensional building-model visualization: (<b>a</b>,<b>c</b>) conflation model with triangle removal; (<b>b</b>,<b>d</b>) original detailed-texture model.</p>
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<p>Building-LOD-model visualization with different screen pixels thresholds: (<b>a</b>) 60 pixels; (<b>b</b>) 120 pixels; (<b>c</b>) 400 pixels.</p>
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<p>Comparison of the frame rates between rendering the origin model and LOD models.</p>
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Article
The Tasks of the Crowd: A Typology of Tasks in Geographic Information Crowdsourcing and a Case Study in Humanitarian Mapping
by João Porto de Albuquerque, Benjamin Herfort and Melanie Eckle
Remote Sens. 2016, 8(10), 859; https://doi.org/10.3390/rs8100859 - 18 Oct 2016
Cited by 60 | Viewed by 16100
Abstract
In the past few years, volunteers have produced geographic information of different kinds, using a variety of different crowdsourcing platforms, within a broad range of contexts. However, there is still a lack of clarity about the specific types of tasks that volunteers can [...] Read more.
In the past few years, volunteers have produced geographic information of different kinds, using a variety of different crowdsourcing platforms, within a broad range of contexts. However, there is still a lack of clarity about the specific types of tasks that volunteers can perform for deriving geographic information from remotely sensed imagery, and how the quality of the produced information can be assessed for particular task types. To fill this gap, we analyse the existing literature and propose a typology of tasks in geographic information crowdsourcing, which distinguishes between classification, digitisation and conflation tasks. We then present a case study related to the “Missing Maps” project aimed at crowdsourced classification to support humanitarian aid. We use our typology to distinguish between the different types of crowdsourced tasks in the project and choose classification tasks related to identifying roads and settlements for an evaluation of the crowdsourced classification. This evaluation shows that the volunteers achieved a satisfactory overall performance (accuracy: 89%; sensitivity: 73%; and precision: 89%). We also analyse different factors that could influence the performance, concluding that volunteers were more likely to incorrectly classify tasks with small objects. Furthermore, agreement among volunteers was shown to be a very good predictor of the reliability of crowdsourced classification: tasks with the highest agreement level were 41 times more probable to be correctly classified by volunteers. The results thus show that the crowdsourced classification of remotely sensed imagery is able to generate geographic information about human settlements with a high level of quality. This study also makes clear the different sophistication levels of tasks that can be performed by volunteers and reveals some factors that may have an impact on their performance. Full article
(This article belongs to the Special Issue Citizen Science and Earth Observation)
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<p>Tomnod platform for classification tasks in Ethiopia. Volunteers are showed an image and should indicate whether they identified buildings in the highlighted area [<a href="#B26-remotesensing-08-00859" class="html-bibr">26</a>].</p>
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<p>The Humanitarian OpenStreetMap Team Tasking Manager [<a href="#B29-remotesensing-08-00859" class="html-bibr">29</a>] is the crowdsourcing tool used to coordinate the simultaneous digitisation efforts of thousands of volunteers worldwide. It presents instructions for volunteers and asks them to select a square to map. By doing this, the selected region is opened for mapping in one of the OpenStreetMap editors.</p>
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<p>PyBossa crowdsourcing tool configured to present conflation tasks aimed at updating and validating shelters mapped after the 2015 Nepal Earthquake. On the (<b>a</b>) side of the image, a more recent image is shown, whereas on the (<b>b</b>) side, the reference image used for mapping is presented. The overlaid <b>blue</b> polygon is a mapped shelter object that comes from the OpenStreetMap database. Volunteers should analyse the three data sources to check if the shelters mapped before are still valid. Source: Anhorn et al. (2016) [<a href="#B23-remotesensing-08-00859" class="html-bibr">23</a>].</p>
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<p>Overview of the methodological workflow of this paper.</p>
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<p>Web user interface of the crowdsourced classification task.</p>
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<p>Contributions per volunteer.</p>
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<p>Task difficulty: (<b>a</b>) tasks without object have a higher share of correct classifications; and (<b>b</b>) a conditional density plot that confirms that tasks with higher number of misclassifications are more probable to contain objects.</p>
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<p>Distribution of user agreement in tasks: (<b>a</b>) tasks without object have a higher share of consensual classifications; and (<b>b</b>) a conditional density plot that confirms that classifications with higher agreement are more probable to contain no objects.</p>
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<p>Violin plot showing the distribution of agreement level of tasks according to the classification result.</p>
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<p>Spatial distribution of number of false negatives, road length and settlement area: (<b>a</b>) number of false negatives/task; (<b>b</b>) road length; and (<b>c</b>) settlement area.</p>
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<p>Violin plots showing the distribution of road length (<b>a</b>) and settlement area (<b>b</b>) according to classification results (both log transformed).</p>
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<p>Examples of “difficult cases”: (<b>a</b>) isolated settlement containing only a few buildings; (<b>b</b>) a road that appears amidst forest areas; (<b>c</b>) image partially covered by clouds; (<b>d</b>) a settlement that is split into two different tasks.</p>
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<p>Spatial distribution of false positives per task and of waterways: (<b>a</b>) number of false positives/task; and (<b>b</b>) waterways.</p>
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<p>Examples of tiles containing waterways that were incorrectly classified by volunteers.</p>
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