ISPRS International Journal of Geo-Information

19 pages, 3301 KiB

Open AccessArticle

A Spatially Explicit Approach for Targeting Resource-Poor Smallholders to Improve Their Participation in Agribusiness: A Case of Nyando and Vihiga County in Western Kenya

by Mwehe Mathenge, Ben G. J. S. Sonneveld and Jacqueline E. W. Broerse

ISPRS Int. J. Geo-Inf. 2020, 9(10), 612; https://doi.org/10.3390/ijgi9100612 - 21 Oct 2020

Cited by 3 | Viewed by 2619

Abstract

The majority of smallholder farmers in Sub-Saharan Africa face myriad challenges to participating in agribusiness markets. However, how the spatially explicit factors interact to influence household decision choices at the local level is not well understood. This paper’s objective is to identify, map, [...] Read more.

The majority of smallholder farmers in Sub-Saharan Africa face myriad challenges to participating in agribusiness markets. However, how the spatially explicit factors interact to influence household decision choices at the local level is not well understood. This paper’s objective is to identify, map, and analyze spatial dependency and heterogeneity in factors that impede poor smallholders from participating in agribusiness markets. Using the researcher-administered survey questionnaires, we collected geo-referenced data from 392 households in Western Kenya. We used three spatial geostatistics methods in Geographic Information System to analyze data—Global Moran’s I, Cluster and Outliers Analysis, and geographically weighted regression. Results show that factors impeding smallholder farmers exhibited local spatial autocorrelation that was linked to the local context. We identified distinct local spatial clusters (hot spots and cold spots clusters) that were spatially and statistically significant. Results affirm that spatially explicit factors play a crucial role in influencing the farming decisions of smallholder households. The paper has demonstrated that geospatial analysis using geographically disaggregated data and methods could help in the identification of resource-poor households and neighborhoods. To improve poor smallholders’ participation in agribusiness, we recommend policymakers to design spatially targeted interventions that are embedded in the local context and informed by locally expressed needs. Full article

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Geographical location of Nyando and Vihiga study areas. Full article ">Figure 2
Steps applied in geocoded household survey design; (a) distribution of randomized GIS points; (b) uploaded KML layers on ‘GPS Essential App’ in Android phone, and (c) Actual surveyed household GPS points. Full article ">Figure 3
Graph showing the most optimal statistically significant peak z-scores of spatial clustering. Full article ">Figure 4
Map of Nyando showing local spatial clusters with a higher concentration of poorer households (hot spots) and richer households (cold spots). Full article ">Figure 5
Map of Vihiga showing local spatial clusters with a higher concentration of poorer households (hot spots) and richer households (cold spots). Full article ">Figure 6
The two maps reveals that, in both Nyando and Vihiga areas, there were more poorer households (red dots) than richer households (blue dots) located within a I Kilometer buffer (crosshatched areas) from the tarmac road, main town, and rivers. Full article ">Figure 7
Survey results showing households head education level vs agribusiness skills possession. Full article ">

19 pages, 4761 KiB

Open AccessArticle

Evolution and Optimization of Urban Network Spatial Structure: A Case Study of Financial Enterprise Network in Yangtze River Delta, China

by Yizhen Zhang, Tao Wang, Agus Supriyadi, Kun Zhang and Zhi Tang

ISPRS Int. J. Geo-Inf. 2020, 9(10), 611; https://doi.org/10.3390/ijgi9100611 - 21 Oct 2020

Cited by 23 | Viewed by 3700

Abstract

The urban network is an important method of spatial optimization, and measuring the development level of the urban network is a prerequisite for spatial optimization. Combining geographic information system (GIS) spatial analysis, social network analysis, and multidimensional scaling models, we explored the evolution [...] Read more.

The urban network is an important method of spatial optimization, and measuring the development level of the urban network is a prerequisite for spatial optimization. Combining geographic information system (GIS) spatial analysis, social network analysis, and multidimensional scaling models, we explored the evolution of the urban network spatial structure in the Yangtze River Delta from 1990 to 2017 and proposed corresponding optimization measures. The results showed that the urban network spatial structure of the Yangtze River Delta has evolved from a single-center cluster with Shanghai as its core to a multi-center network with Shanghai as its core and Nanjing, Hangzhou, and Hefei as secondary cores. The density of the urban network has gradually expanded, but the strength of the connection between edge cities such as Chizhou, Suqian, and Quzhou and the core cities needs to be further improved. We found that the evolution of the urban network spatial structure has been driven by preferential attachment, path dependence, and differences in economic and industrial development. Finally, we propose optimizing the urban network spatial structure by strengthening the driving ability of the core cities, clarifying urban functions and development directions, and establishing a unified coordination mechanism. This paper enriches and deepens our understanding of the characteristics of the city network in the Yangtze River Delta, and provides a reference for the optimization of the urban network spatial structure. Full article

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Study area and location of the Yangtze River Delta in China. Full article ">Figure 2
Location and number of financial companies in the Yangtze River Delta. Full article ">Figure 3
Operation principle of the modularity model. We divided closely connected cities into different communities through a modularity model. (a) The blue nodes represent all the different cities. (b) After modularity optimization, some closely connected cities are selected, and cities of the same color are in the same community. (c) The cities of the same color are grouped into the same community after modularity division. Full article ">Figure 4
Intercity network for the Yangtze River Delta from 1990 to 2017. The weight of the edge represents the R value (the total connection strength between cities) calculated above. Full article ">Figure 4 Cont.
Intercity network for the Yangtze River Delta from 1990 to 2017. The weight of the edge represents the R value (the total connection strength between cities) calculated above. Full article ">Figure 5
Network community division in the Yangtze River Delta from 1990 to 2017. The weight of the edge represents the R value (the total connection strength between cities) as calculated above. The same color is used to represent the cities in the same community, and the size of the node represents the degree centrality. (a–d) show the evolution of network community in 1990, 2000, 2008, and 2017, respectively. Full article ">Figure 6
Evolution Mode of Urban Network Spatial Structure in Yangtze River Delta from 1990 to 2017. Note: <img alt="Ijgi 09 00611 i005" src="/ijgi/ijgi-09-00611/article_deploy/html/images/ijgi-09-00611-i005.png"/> represents a type I city, <img alt="Ijgi 09 00611 i006" src="/ijgi/ijgi-09-00611/article_deploy/html/images/ijgi-09-00611-i006.png"/> represents a type II city, <img alt="Ijgi 09 00611 i007" src="/ijgi/ijgi-09-00611/article_deploy/html/images/ijgi-09-00611-i007.png"/> represents a type III city, <img alt="Ijgi 09 00611 i008" src="/ijgi/ijgi-09-00611/article_deploy/html/images/ijgi-09-00611-i008.png"/> represents a type IV city. The green surrounding the red node refers to the research of Li et al., and to a certain extent represents the urban hinterland. [<a href="#B14-ijgi-09-00611" class="html-bibr">14</a>]. Full article ">

17 pages, 10168 KiB

Open AccessArticle

Articulated Trajectory Mapping for Reviewing Walking Tours

by Iori Sasaki, Masatoshi Arikawa and Akinori Takahashi

ISPRS Int. J. Geo-Inf. 2020, 9(10), 610; https://doi.org/10.3390/ijgi9100610 - 21 Oct 2020

Cited by 5 | Viewed by 2752

Abstract

This paper addresses how to enrich a map-based representation for reviewing walking tours with the features of trajectory mapping and tracing animation. Generally, a trajectory generated by raw GPS data can often be difficult to browse through on a map. To resolve this [...] Read more.

This paper addresses how to enrich a map-based representation for reviewing walking tours with the features of trajectory mapping and tracing animation. Generally, a trajectory generated by raw GPS data can often be difficult to browse through on a map. To resolve this issue, we first illustrated tangled trajectory lines, inaccurate indoor positioning, and unstable trajectory lines as problems encountered when mapping raw trajectory data. Then, we proposed a new framework that focuses on GPS horizontal accuracy to locate indoor location points and find stopping points on an accelerometer. We also applied a conventional line simplification algorithm to make the trajectory cleaner and then integrated the extracted points with the clean trajectory line. Furthermore, our experiments with some actual logs of walking tours demonstrated that articulated trajectory mapping, which comprises simplification and characterization methods, sufficiently reliable and effective for better reviewing experiences. The paper contributes to the research on cleaning up map-based displays and tracing animations of raw trajectory GPS data by using not only location data but also sensor data that smartphones can collect. Full article

(This article belongs to the Special Issue Recent Trends in Location Based Services and Science)

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23 pages, 7669 KiB

Open AccessEditor’s ChoiceArticle

A 3D Geodatabase for Urban Underground Infrastructures: Implementation and Application to Groundwater Management in Milan Metropolitan Area

by Davide Sartirana, Marco Rotiroti, Chiara Zanotti, Tullia Bonomi, Letizia Fumagalli and Mattia De Amicis

ISPRS Int. J. Geo-Inf. 2020, 9(10), 609; https://doi.org/10.3390/ijgi9100609 - 21 Oct 2020

Cited by 8 | Viewed by 4415

Abstract

The recent rapid increase in urbanization has led to the inclusion of underground spaces in urban planning policies. Among the main subsurface resources, a strong interaction between underground infrastructures and groundwater has emerged in many urban areas in the last few decades. Thus, [...] Read more.

The recent rapid increase in urbanization has led to the inclusion of underground spaces in urban planning policies. Among the main subsurface resources, a strong interaction between underground infrastructures and groundwater has emerged in many urban areas in the last few decades. Thus, listing the underground infrastructures is necessary to structure an urban conceptual model for groundwater management needs. Starting from a municipal cartography (Open Data), thus making the procedure replicable, a GIS methodology was proposed to gather all the underground infrastructures into an updatable 3D geodatabase (GDB) for the metropolitan city of Milan (Northern Italy). The underground volumes occupied by three categories of infrastructures were included in the GDB: (a) private car parks, (b) public car parks and (c) subway lines and stations. The application of the GDB allowed estimating the volumes lying below groundwater table in four periods, detected as groundwater minimums or maximums from the piezometric trend reconstructions. Due to groundwater rising or local hydrogeological conditions, the shallowest, non-waterproofed underground infrastructures were flooded in some periods considered. This was evaluated in a specific pilot area and qualitatively confirmed by local press and photographic documentation reviews. The methodology emerged as efficient for urban planning, particularly for urban conceptual models and groundwater management plans definition. Full article

(This article belongs to the Special Issue Measuring, Mapping, Modeling, and Visualization of Cities)

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14 pages, 4883 KiB

Open AccessEditor’s ChoiceArticle

Accurate Road Marking Detection from Noisy Point Clouds Acquired by Low-Cost Mobile LiDAR Systems

by Ronghao Yang, Qitao Li, Junxiang Tan, Shaoda Li and Xinyu Chen

ISPRS Int. J. Geo-Inf. 2020, 9(10), 608; https://doi.org/10.3390/ijgi9100608 - 20 Oct 2020

Cited by 22 | Viewed by 4185

Abstract

Road markings that provide instructions for unmanned driving are important elements in high-precision maps. In road information collection technology, multi-beam mobile LiDAR scanning (MLS) is currently adopted instead of traditional mono-beam LiDAR scanning because of the advantages of low cost and multiple fields [...] Read more.

Road markings that provide instructions for unmanned driving are important elements in high-precision maps. In road information collection technology, multi-beam mobile LiDAR scanning (MLS) is currently adopted instead of traditional mono-beam LiDAR scanning because of the advantages of low cost and multiple fields of view for multi-beam laser scanners; however, the intensity information scanned by multi-beam systems is noisy and current methods designed for road marking detection from mono-beam point clouds are of low accuracy. This paper presents an accurate algorithm for detecting road markings from noisy point clouds, where most nonroad points are removed and the remaining points are organized into a set of consecutive pseudo-scan lines for parallel and/or online processing. The road surface is precisely extracted by a moving fitting window filter from each pseudo-scan line, and a marker edge detector combining an intensity gradient with an intensity statistics histogram is presented for road marking detection. Quantitative results indicate that the proposed method achieves average recall, precision, and Matthews correlation coefficient (MCC) levels of 90%, 95%, and 92%, respectively, showing excellent performance for road marking detection from multi-beam scanning point clouds. Full article

(This article belongs to the Special Issue Measuring, Mapping, Modeling, and Visualization of Cities)

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20 pages, 2913 KiB

Open AccessArticle

Privacy-Aware Visualization of Volunteered Geographic Information (VGI) to Analyze Spatial Activity: A Benchmark Implementation

by Alexander Dunkel, Marc Löchner and Dirk Burghardt

ISPRS Int. J. Geo-Inf. 2020, 9(10), 607; https://doi.org/10.3390/ijgi9100607 - 20 Oct 2020

Cited by 17 | Viewed by 3775

Abstract

Through volunteering data, people can help assess information on various aspects of their surrounding environment. Particularly in natural resource management, Volunteered Geographic Information (VGI) is increasingly recognized as a significant resource, for example, supporting visitation pattern analysis to evaluate collective values and improve [...] Read more.

Through volunteering data, people can help assess information on various aspects of their surrounding environment. Particularly in natural resource management, Volunteered Geographic Information (VGI) is increasingly recognized as a significant resource, for example, supporting visitation pattern analysis to evaluate collective values and improve natural well-being. In recent years, however, user privacy has become an increasingly important consideration. Potential conflicts often emerge from the fact that VGI can be re-used in contexts not originally considered by volunteers. Addressing these privacy conflicts is particularly problematic in natural resource management, where visualizations are often explorative, with multifaceted and sometimes initially unknown sets of analysis outcomes. In this paper, we present an integrated and component-based approach to privacy-aware visualization of VGI, specifically suited for application to natural resource management. As a key component, HyperLogLog (HLL)—a data abstraction format—is used to allow estimation of results, instead of more accurate measurements. While HLL alone cannot preserve privacy, it can be combined with existing approaches to improve privacy while, at the same time, maintaining some flexibility of analysis. Together, these components make it possible to gradually reduce privacy risks for volunteers at various steps of the analytical process. A specific use case demonstration is provided, based on a global, publicly-available dataset that contains 100 million photos shared by 581,099 users under Creative Commons licenses. Both the data processing pipeline and resulting dataset are made available, allowing transparent benchmarking of the privacy–utility tradeoffs. Full article

(This article belongs to the Special Issue Volunteered Geographic Information and Citizen Science)

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26 pages, 3605 KiB

Open AccessArticle

Towards Deriving Freight Traffic Measures from Truck Movement Data for State Road Planning: A Proposed System Framework

by Ahmed Karam, Thorbjørn M. Illemann, Kristian Hegner Reinau, Goran Vuk and Christian O. Hansen

ISPRS Int. J. Geo-Inf. 2020, 9(10), 606; https://doi.org/10.3390/ijgi9100606 - 14 Oct 2020

Cited by 6 | Viewed by 3533

Abstract

To make the right decisions on investments, operations, and policies in the public road sector, decision makers need knowledge about traffic measures of trucks, such as average travel time and the frequency of trips among geographical zones. Private logistics companies daily collect a [...] Read more.

To make the right decisions on investments, operations, and policies in the public road sector, decision makers need knowledge about traffic measures of trucks, such as average travel time and the frequency of trips among geographical zones. Private logistics companies daily collect a large amount of freight global positioning system (GPS) and shipment data. Processing such data can provide public decision makers with detailed freight traffic measures, which are necessary for making different planning decisions. The present paper proposes a system framework to be used in the research project “A new system for sharing data between logistics companies and public infrastructure authorities: improving infrastructure while maintaining competitive advantage”. Previous studies ignored the fact that the primary step for delivering valuable and usable data processing systems is to consider the final user’s needs when developing the system framework. Unlike existing studies, this paper develops the system framework through applying a user-centred design approach combining three main steps. The first step is to identify the specific traffic measures that satisfy the public decision makers’ planning needs. The second step aims to identify the different types of freight data required as inputs to the data processing system, while the third step illustrates the procedures needed to process the shared freight data. To do so, the current work employs methods of literature review and users’ need identification in applying a user-centralized approach. In addition, we develop a systematic assessment of the coverage and sufficiency of the currently acquired data. Finally, we illustrate the detailed functionality of the data processing system and provide an application case to illustrate its procedures. Full article

(This article belongs to the Special Issue Recent Trends in Location Based Services and Science)

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17 pages, 10280 KiB

Open AccessArticle

Is Crowdsourcing a Reliable Method for Mass Data Acquisition? The Case of COVID-19 Spread in Greece During Spring 2020

by Varvara Antoniou, Emmanuel Vassilakis and Maria Hatzaki

ISPRS Int. J. Geo-Inf. 2020, 9(10), 605; https://doi.org/10.3390/ijgi9100605 - 14 Oct 2020

Cited by 17 | Viewed by 4284

Abstract

We present a GIS-based crowdsourcing application that was launched soon after the first COVID-19 cases had been recorded in Greece, motivated by the need for fast, location-wise data acquisition regarding COVID-19 disease spread during spring 2020, due to limited testing. A single question [...] Read more.

We present a GIS-based crowdsourcing application that was launched soon after the first COVID-19 cases had been recorded in Greece, motivated by the need for fast, location-wise data acquisition regarding COVID-19 disease spread during spring 2020, due to limited testing. A single question was posted through a web App, to which the anonymous participants subjectively answered whether or not they had experienced any COVID-19 disease symptoms. Our main goal was to locate geographical areas with increased number of people feeling the symptoms and to determine any temporal changes in the statistics of the survey entries. It was found that the application was rapidly disseminated to the entire Greek territory via social media, having, thus, a great public reception. The higher percentages of participants experiencing symptoms coincided geographically with the highly populated urban areas, having also increased numbers of confirmed cases, while temporal variations were detected that accorded with the restrictions of activities. This application demonstrates that health systems can use crowdsourcing applications that assure anonymity, as an alternative to tracing apps, to identify possible hot spots and to reach and warn the public within a short time interval, increasing at the same time their situational awareness. However, a continuous reminder for participation should be scheduled. Full article

(This article belongs to the Collection Spatial Components of COVID-19 Pandemic)

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Interface of the survey in Greek and English (<a href="https://arcg.is/1yiXG4" target="_blank">https://arcg.is/1yiXG4</a>). Full article ">Figure 2
Dashboard showing the survey responders location, in real time (map on the left) and aggregation analysis for “Not Sure” (map in the middle) and “Yes” (map on the right) per Regional Unit performed every 3 hours (<a href="https://arcg.is/00Kanf" target="_blank">https://arcg.is/00Kanf</a>). Indicators below the maps show the total number of responders, Not Sure and Yes, respectively. Screenshot was taken on 18/03/2020 12:00 (EET). Full article ">Figure 3
Spatial distribution of survey entries, the majority of which are located in the Regions of Attica and Central Macedonia. Black lines indicate geographical boundaries of the Regions. Green points indicate No, light green Not Sure and red points Yes answers; black circles indicate bigger cities. Full article ">Figure 4
Temporal evolution for the Greek territory of (a) the number of participants per day with the number of Yes and Not Sure annotated; (b) ratios of the three different answers per day (left axis), compared to the confirmed cases (number/day; right axis); (c) the confirmed cases and deaths per day since the recording of the first confirmed case in Greece. Critical restriction of activities is also indicated with vertical solid or dashed lines. Full article ">Figure 5
Spatial distribution of survey entries for (a) the Region of Attica and (b) the Athens metropolitan area. Temporal evolution for the Region of Attica of (c) the number of participants per day with the number of Yes and Not Sure annotated, (d) ratios of the three different answers per day (left axis), compared to the confirmed cases (number/day; right axis), (e) the confirmed cases and deaths per day in Attica since the recording of the first confirmed case in Greece. Critical restriction of activities is also indicated with vertical solid or dashed lines. Full article ">Figure 6
Spatial distribution of survey entries for (a) the Region of Central Macedonia and (b) the greater area of Thessaloniki. Temporal evolution for the Region of Central Macedonia of (c) the number of participants per day with the number of Yes and Not Sure annotated; (d) ratios of the three different answers per day (left axis), compared to the confirmed cases (number/day; right axis); (e) the confirmed cases and deaths per day in Central Macedonia since the recording of the first confirmed case in Greece. Critical restriction of activities is also indicated with vertical solid or dashed lines. Full article ">Figure 7
Hot spot analysis for Athens metropolitan area and surrounding towns on daily basis for the first eight days of the survey. Full article ">

25 pages, 15167 KiB

Open AccessArticle

Reconstruction of Lost Cultural Heritage Sites and Landscapes: Context of Ancient Objects in Time and Space

by Lukáš Brůha, Josef Laštovička, Tomáš Palatý, Eva Štefanová and Přemysl Štych

ISPRS Int. J. Geo-Inf. 2020, 9(10), 604; https://doi.org/10.3390/ijgi9100604 - 14 Oct 2020

Cited by 16 | Viewed by 4464

Abstract

Diachronic studies play a key role in the research and documentation of cultural heritage and its changes, ranging from architectural fragments to landscape. Regarding the reconstructions of lost cultural heritage sites, the determination of landscape conditions in the reconstructed era goes frequently unheeded. [...] Read more.

Diachronic studies play a key role in the research and documentation of cultural heritage and its changes, ranging from architectural fragments to landscape. Regarding the reconstructions of lost cultural heritage sites, the determination of landscape conditions in the reconstructed era goes frequently unheeded. Often, only ruins and detached archeological artefacts remain of the built heritage. Placing them correctly within the reconstructed building complex is of similar importance as placing the lost monument in the context of the landscape at that time. The proposed method harmonizes highly heterogeneous sources to provide such a context. The solution includes the fusion of referential terrain models of different levels of detail (LODs) as well as the fusion of diverse 3D data sources for the reconstruction of the built heritage. Although the combined modeling of large landscapes and small 3D objects of a high detail results in very large datasets, we present a feasible solution, whose data structure is suitable for Geographic Information Systems (GIS) analyses of landscapes and also provides a smooth and clear 3D visualization and inspection of detailed features. The results are demonstrated in the case study of the island monastery, the vanished medieval town of Sekanka, and the surrounding landscape, which is located in Czechia and was the subject of intensive changes over time. Full article

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32 pages, 7257 KiB

Open AccessArticle

Detailed Streetspace Modelling for Multiple Applications: Discussions on the Proposed CityGML 3.0 Transportation Model

by Christof Beil, Roland Ruhdorfer, Theresa Coduro and Thomas H. Kolbe

ISPRS Int. J. Geo-Inf. 2020, 9(10), 603; https://doi.org/10.3390/ijgi9100603 - 13 Oct 2020

Cited by 30 | Viewed by 6385

Abstract

In the context of smart cities and digital twins, three-dimensional semantic city models are increasingly used for the analyses of large urban areas. While the representation of buildings, terrain, and vegetation has become standard for most city models, detailed spatio-semantic representations of streetspace [...] Read more.

In the context of smart cities and digital twins, three-dimensional semantic city models are increasingly used for the analyses of large urban areas. While the representation of buildings, terrain, and vegetation has become standard for most city models, detailed spatio-semantic representations of streetspace have played a minor role so far. This is now changing (1) because of data availability, and (2) because recent and emerging applications require having detailed data about the streetspace. The upcoming version 3.0 of the international standard CityGML provides a substantially updated data model regarding the transportation infrastructure, including the representation of the streetspace. However, there already exist a number of other standards and data formats dealing with the representation and exchange of streetspace data. Thus, based on an extensive literature review of potential applications as well as discussions and collaborations with relevant stakeholders, seven key modelling aspects of detailed streetspace models are identified. This allows a structured discussion of representational capabilities of the proposed CityGML3.0 Transportation Model with respect to these aspects and in comparison to the other standards. Subsequently, it is shown that CityGML3.0 meets most of these aspects and that streetspace models can be derived from various data sources and for different cities. Models generated compliant to the CityGML standard are immediately usable for a number of applications. This is demonstrated for some applications, such as land use management, solar potential analyses, and traffic and pedestrian simulations. Full article

(This article belongs to the Special Issue The Applications of 3D-City Models in Urban Studies)

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19 pages, 4739 KiB

Open AccessEditor’s ChoiceArticle

Concept and Evaluation of Heating Demand Prediction Based on 3D City Models and the CityGML Energy ADE—Case Study Helsinki

by Maxim Rossknecht and Enni Airaksinen

ISPRS Int. J. Geo-Inf. 2020, 9(10), 602; https://doi.org/10.3390/ijgi9100602 - 12 Oct 2020

Cited by 35 | Viewed by 4984

Abstract

This work presents a concept for heating demand and resulting CO

_{2}

emissions prediction based on a 3D city model in CityGML format in various scenarios under the consideration of a changing climate. In the case study of Helsinki, the Helsinki Energy and [...] Read more.

This work presents a concept for heating demand and resulting CO

_{2}

emissions prediction based on a 3D city model in CityGML format in various scenarios under the consideration of a changing climate. In the case study of Helsinki, the Helsinki Energy and Climate Atlas, that provides detailed information for individual buildings conducting the heating demand, is integrated into the 3D city model using the CityGML Energy Application Domain Extension (Energy ADE) to provide energy-relevant information based on a standardized data model stored in a CityGML database, called 3DCityDB. The simulation environment SimStadt is extended to retrieve the information stored within the Energy ADE schema, use it during simulations, and write simulation results back to the 3DCityDB. Due to climate change, a heating demand reduction of 4% per decade is predicted. By 2035, a reduction of 0.7 TWh is calculated in the normal and of 1.5 TWh in the advanced refurbishment scenario. Including the proposed improvements of the district heating network, heating CO

_{2}

emissions are predicted to be reduced by up to 82% by 2035 compared to 1990. The City of Helsinki’s assumed heating demand reduction through the modernization of 2.0 TWh/a by 2035 is not achieved with a 3% refurbishment rate. Furthermore, the reduction of CO

_{2}

emissions is mainly achieved through lower CO

_{2}

emission factors of the district heating network in Helsinki. Full article

(This article belongs to the Special Issue The Applications of 3D-City Models in Urban Studies)

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15 pages, 2358 KiB

Open AccessArticle

Semantic Segmentation of Remote-Sensing Imagery Using Heterogeneous Big Data: International Society for Photogrammetry and Remote Sensing Potsdam and Cityscape Datasets

by Ahram Song and Yongil Kim

ISPRS Int. J. Geo-Inf. 2020, 9(10), 601; https://doi.org/10.3390/ijgi9100601 - 12 Oct 2020

Cited by 19 | Viewed by 5232

Abstract

Although semantic segmentation of remote-sensing (RS) images using deep-learning networks has demonstrated its effectiveness recently, compared with natural-image datasets, obtaining RS images under the same conditions to construct data labels is difficult. Indeed, small datasets limit the effective learning of deep-learning networks. To [...] Read more.

Although semantic segmentation of remote-sensing (RS) images using deep-learning networks has demonstrated its effectiveness recently, compared with natural-image datasets, obtaining RS images under the same conditions to construct data labels is difficult. Indeed, small datasets limit the effective learning of deep-learning networks. To address this problem, we propose a combined U-net model that is trained using a combined weighted loss function and can handle heterogeneous datasets. The network consists of encoder and decoder blocks. The convolutional layers that form the encoder blocks are shared with the heterogeneous datasets, and the decoder blocks are assigned separate training weights. Herein, the International Society for Photogrammetry and Remote Sensing (ISPRS) Potsdam and Cityscape datasets are used as the RS and natural-image datasets, respectively. When the layers are shared, only visible bands of the ISPRS Potsdam data are used. Experimental results show that when same-sized heterogeneous datasets are used, the semantic segmentation accuracy of the Potsdam data obtained using our proposed method is lower than that obtained using only the Potsdam data (four bands) with other methods, such as SegNet, DeepLab-V3+, and the simplified version of U-net. However, the segmentation accuracy of the Potsdam images is improved when the larger Cityscape dataset is used. The combined U-net model can effectively train heterogeneous datasets and overcome the insufficient training data problem in the context of RS-image datasets. Furthermore, it is expected that the proposed method can not only be applied to segmentation tasks of aerial images but also to tasks with various purposes of using big heterogeneous datasets. Full article

(This article belongs to the Special Issue Geospatial Big Data and Machine Learning Opportunities and Prospects)

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Architecture of the combined U-net model. “Conv2D” denotes the two-dimensional (2D) convolutional layers, and “Conv2DTranspose” denotes a transposed 2D convolutional layer. “Concatenate” denotes a concatenated layer. Full article ">Figure 2
Framework of the proposed method. The combined U-net model shares encoding blocks and is trained using the combined weighted loss. Full article ">Figure 3
Example of the International Society for Photogrammetry and Remote Sensing (ISPRS) dataset; the patch number is 2–10: (a) RGB-image, (b) labeling image, (c) enlarged RGB-image, and (d) data labels. Full article ">Figure 4
Examples from the Cityscape dataset: (a,d) RGB-images, (b,e) original label images, and (c,f) redefined label images. Full article ">Figure 5
Final label classes of the Potsdam and Cityscape datasets. Full article ">Figure 6
Learning graph of the overall accuracy (OA) for each epoch. (a) SegNet with original bands of Potsdam dataset, (b) DeepLab-V3+ with original bands of Potsdam dataset, (c) simplified U-net with RGB bands of Potsdam dataset, (d) simplified U-net with original bands of Potsdam dataset, (e) Case 1 wherein training proceeded using both the Potsdam and Cityscape datasets (same sizes) by the combined U-net method. (f) Case 2 wherein training proceeded using the Potsdam and Cityscape datasets by the combined U-net method; however, the Cityscape dataset was about twice as large as the Potsdam dataset. Full article ">Figure 7
Example of input Potsdam RGB, label, and the resulting semantic segmentation images for the three cases. (a,f,k,q) are the input Potsdam images, (b,g,l,r) are the label images, (c,h,m,s) are the resulting images generated in simplified U-net, (d,i,n,t) are the resulting images generated in Case 1, and (e,j,o,u) are the resulting images generated in Case 2. Full article ">Figure 8
OA and loss of the test set when (a) the number of Cityscape datasets was varied and when (b) the weight values of the Potsdam and Cityscape were changed Full article ">

19 pages, 5103 KiB

Open AccessEditor’s ChoiceArticle

Assessing Quality of Life Inequalities. A Geographical Approach

by Antigoni Faka

ISPRS Int. J. Geo-Inf. 2020, 9(10), 600; https://doi.org/10.3390/ijgi9100600 - 12 Oct 2020

Cited by 23 | Viewed by 5086

Abstract

This study proposes an integrated methodology for evaluating and mapping quality of life (QoL) and the quality of a place as residence area, at local level. The QoL assessment was based on the development of composite criteria, using geographical variables that evaluate QoL, [...] Read more.

This study proposes an integrated methodology for evaluating and mapping quality of life (QoL) and the quality of a place as residence area, at local level. The QoL assessment was based on the development of composite criteria, using geographical variables that evaluate QoL, and geographic information systems. The composite criteria are related to the natural and the socioeconomic environment, the housing conditions, the infrastructure and services, and the cultural and recreational facilities. Each criterion was evaluated by a set of variables and each variable was weighted based on the residents’ preferences and the analytical hierarchy process. The criteria were also weighted and combined to assess overall QoL. The methodology was implemented in the Municipality of Katerini, Greece, and QoL mapping led to the zoning of the study area and the identification of areas with low and high QoL. The results revealed the highest level of overall QoL in three out of twenty-nine communities, which provide better housing conditions and access to public services and infrastructures, combining also qualitative natural environment, whereas five mountainous and remote communities scored the lowest level. Mapping QoL may support decision making strategies that target to improve human well-being, increase QoL levels and upgrade living conditions. Full article

(This article belongs to the Special Issue GIS-Based Analysis for Quality of Life and Environmental Monitoring)

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Municipality of Katerini and local administrative units (LAUs). LAUs are described by ID in <a href="#ijgi-09-00600-t001" class="html-table">Table 1</a>. Full article ">Figure 2
Flowchart of the proposed methodology. Full article ">Figure 3
Spatial layers of factors per criterion. (a) spatial layers of public services and infrastructures, (b) spatial layers of cultural and recreational facilities, (c) spatial layers of natural environment. Full article ">Figure 4
Variables of socioeconomic environment and housing conditions (%), LAUs of the Katerini Municipality. (a) percentage of unemployment, (b) percentage of higher educated population, (c) percentage of employment in upper occupational groups, (d) percentage of employment in lower occupational groups, (e) percentage of households without basic facilities, (f) percentage of households in detached houses, (g) percentage of households in newly built units, (h) housing space per person in m2. Full article ">Figure 5
Variables of public services and infrastructures, cultural and recreational facilities, and natural environment, LAUs of Katerini Municipality. (a) accessibility to medical services in minutes, (b) accessibility to educational facilities in minutes, (c) accessibility to sport facilities in minutes, (d) accessibility to urban amenities in minutes, (e) internet network density (Km/sq. Km), (f) accessibility to leisure facilities in minutes, (g) accessibility to cultural facilities in minutes, (h) accessibility to coastline in minutes, (i) percentage of urban areas, (j) percentage of forestlands. Full article ">Figure 6
Maps of the QoL criteria, LAUs of Katerini Municipality. (a) socioeconomic environment, (b) housing conditions, (c) public services and infrastructures, (d) cultural and recreational facilities, (e) natural environment. Full article ">Figure 7
Overall QoL levels, LAUs of the Katerini Municipality. Full article ">

14 pages, 2222 KiB

Open AccessArticle

Spatial Patterns of Childhood Obesity Prevalence in Relation to Socioeconomic Factors across England

by Yeran Sun, Xuke Hu, Ying Huang and Ting On Chan

ISPRS Int. J. Geo-Inf. 2020, 9(10), 599; https://doi.org/10.3390/ijgi9100599 - 11 Oct 2020

Cited by 6 | Viewed by 5254

Abstract

To examine to what extent spatial inequalities in childhood obesity are attributable to spatial inequalities in socioeconomic characteristics across a country, we aimed to investigate the spatial associations of socioeconomic characteristics and childhood obesity. We first explored spatial patterns of childhood obesity prevalence, [...] Read more.

To examine to what extent spatial inequalities in childhood obesity are attributable to spatial inequalities in socioeconomic characteristics across a country, we aimed to investigate the spatial associations of socioeconomic characteristics and childhood obesity. We first explored spatial patterns of childhood obesity prevalence, and subsequently investigated the spatial associations of socioeconomic factors and childhood obesity prevalence across England by selecting and estimating appropriate spatial regression models. As the data used are geospatial data, we used two newly developed specifications of spatial regression models to investigate the spatial association of socioeconomic factors and childhood obesity prevalence. As a result, among the two newly developed specifications of spatial regression models, the fast random effects specification of eigenvector spatial filtering (FRES-ESF) model appears to outperform the matrix exponential spatial specification of spatial autoregressive (MESS-SAR) model. Empirical results indicate that positive spatial dependence is found to exist in childhood obesity prevalence across England; and that socioeconomic factors are significantly associated with childhood obesity prevalence across England. In England, children living in areas with lower socioeconomic status are at higher risk of obesity. This study suggests effectively reducing spatial inequalities in socioeconomic status will plays a vital role in mitigating spatial inequalities in childhood obesity prevalence. Full article

(This article belongs to the Special Issue Geographical Analysis, Urban Modelling, Spatial Statistics, Econometric and Multidimensional Evaluation in Urban Environment)

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18 pages, 4004 KiB

Open AccessArticle

Simulating Large-Scale 3D Cadastral Dataset Using Procedural Modelling

by Jernej Tekavec, Anka Lisec and Eugénio Rodrigues

ISPRS Int. J. Geo-Inf. 2020, 9(10), 598; https://doi.org/10.3390/ijgi9100598 - 11 Oct 2020

Cited by 8 | Viewed by 2984

Abstract

Geospatial data and information within contemporary land administration systems are fundamental to manage the territory adequately. 3D land administration systems, often addressed as 3D cadastre, promise several benefits, particularly in managing today’s complex built environment, but these are currently still non-existent in their [...] Read more.

Geospatial data and information within contemporary land administration systems are fundamental to manage the territory adequately. 3D land administration systems, often addressed as 3D cadastre, promise several benefits, particularly in managing today’s complex built environment, but these are currently still non-existent in their full capacity. The development of any complex information and administration system, such as a land administration system, is time-consuming and costly, particularly during the phase of evaluation and testing. In this regard, the process of implementing such systems may benefit from using synthetic data. In this study, the method for simulating the 3D cadastral dataset is presented and discussed. The dataset is generated using a procedural modelling method, referenced to real cadastral data for the Slovenian territory and stored in a spatial database management system (DBMS) that supports storage of 3D spatial data. Spatial queries, related to 3D cadastral data management, are used to evaluate the database performance and storage characteristics, and 3D visualisation options. The results of the study show that the method is feasible for the simulation of large-scale 3D cadastral datasets. Using the developed spatial queries and their performance analysis, we demonstrate the importance of the simulated dataset for developing efficient 3D cadastral data management processes. Full article

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25 pages, 16093 KiB

Open AccessArticle

Spatial and Temporal Patterns in Volunteer Data Contribution Activities: A Case Study of eBird

by Guiming Zhang

ISPRS Int. J. Geo-Inf. 2020, 9(10), 597; https://doi.org/10.3390/ijgi9100597 - 11 Oct 2020

Cited by 32 | Viewed by 5355

Abstract

Volunteered geographic information (VGI) has great potential to reveal spatial and temporal dynamics of geographic phenomena. However, a variety of potential biases in VGI are recognized, many of which root from volunteer data contribution activities. Examining patterns in volunteer data contribution activities helps [...] Read more.

Volunteered geographic information (VGI) has great potential to reveal spatial and temporal dynamics of geographic phenomena. However, a variety of potential biases in VGI are recognized, many of which root from volunteer data contribution activities. Examining patterns in volunteer data contribution activities helps understand the biases. Using eBird as a case study, this study investigates spatial and temporal patterns in data contribution activities of eBird contributors. eBird sampling efforts are biased in space and time. Most sampling efforts are concentrated in areas of denser populations and/or better accessibility, with the most intensively sampled areas being in proximity to big cities in developed regions of the world. Reported bird species are also spatially biased towards areas where more sampling efforts occur. Temporally, eBird sampling efforts and reported bird species are increasing over the years, with significant monthly fluctuations and notably more data reported on weekends. Such trends are driven by the expansion of eBird and characteristics of bird species and observers. The fitness of use of VGI should be assessed in the context of applications by examining spatial, temporal and other biases. Action may need to be taken to account for the biases so that robust inferences can be made from VGI observations. Full article

(This article belongs to the Special Issue Citizen Science and Geospatial Capacity Building)

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16 pages, 42937 KiB

Open AccessEditor’s ChoiceArticle

A Smooth Transition Algorithm for Adjacent Panoramic Viewpoints Using Matched Delaunay Triangular Patches

by Pengcheng Zhao, Qingwu Hu, Zhixiong Tang and Mingyao Ai

ISPRS Int. J. Geo-Inf. 2020, 9(10), 596; https://doi.org/10.3390/ijgi9100596 - 10 Oct 2020

Cited by 5 | Viewed by 3956

Abstract

The unnatural panoramic image transition between two adjacent viewpoints reduces the immersion and interactive experiences of 360° panoramic walkthrough systems. In this paper, a dynamic panoramic image rendering and smooth transition algorithm for adjacent viewpoints is proposed. First, the feature points of adjacent [...] Read more.

The unnatural panoramic image transition between two adjacent viewpoints reduces the immersion and interactive experiences of 360° panoramic walkthrough systems. In this paper, a dynamic panoramic image rendering and smooth transition algorithm for adjacent viewpoints is proposed. First, the feature points of adjacent view images are extracted, a robust matching algorithm is used to establish adjacent point pairs, and the matching triangles are formed by using the homonymous points. Then, a dynamic transition model is formed by the simultaneous linear transitions of shape and texture for each control triangle. Finally, the smooth transition between adjacent viewpoints is implemented by overlaying the dynamic transition model with the 360° panoramic walkthrough scene. Experimental results show that this method has obvious advantages in visual representation with distinct visual movement. It can realize the smooth transition between two indoor panoramic stations with arbitrary station spacing, and its execution efficiency is up to 50 frames per second. It effectively enhances the interactivity and immersion of 360° panoramic walkthrough systems. Full article

(This article belongs to the Special Issue Measuring, Mapping, Modeling, and Visualization of Cities)

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Principle schematic diagram of panorama transition guided by matched triangular patches. Full article ">Figure 2
Proposed technique workflow for smooth transition between adjacent viewpoints. Full article ">Figure 3
Generation flow chart of triangular patches for controlling transition. The green arrow represents the direction of execution of the local projection, and the red arrow represents the direction of execution of the back projection. The picture at the bottom right shows the extracted control triangular patches. Full article ">Figure 4
Demonstration of the transition from one tri angle to another. Full article ">Figure 5
Middle textures generated by the smooth transition algorithm. The panorama scene transitions from the current site to the next with the process ranging from 0.0 to 1.0. The control patches transition from a small piece on the sphere to a hemi-spherical surface as the viewpoint moves forward. Full article ">Figure 6
The dynamic panoramic ball display strategy. The outer layer is a panoramic sphere for roaming, and the inner layer is the morph layer for smooth site transitions. Full article ">Figure 7
Visual performance of the 360° panoramic walkthrough system with smooth transitions between adjacent viewpoints. The panorama scene transitions from the current site to the next with the process ranging from 0.0 to 1.0. Full article ">

26 pages, 13177 KiB

Open AccessArticle

Hierarchical Instance Recognition of Individual Roadside Trees in Environmentally Complex Urban Areas from UAV Laser Scanning Point Clouds

by Yongjun Wang, Tengping Jiang, Jing Liu, Xiaorui Li and Chong Liang

ISPRS Int. J. Geo-Inf. 2020, 9(10), 595; https://doi.org/10.3390/ijgi9100595 - 10 Oct 2020

Cited by 22 | Viewed by 3477

Abstract

Individual tree segmentation is essential for many applications in city management and urban ecology. Light Detection and Ranging (LiDAR) system acquires accurate point clouds in a fast and environmentally-friendly manner, which enables single tree detection. However, the large number of object categories and [...] Read more.

Individual tree segmentation is essential for many applications in city management and urban ecology. Light Detection and Ranging (LiDAR) system acquires accurate point clouds in a fast and environmentally-friendly manner, which enables single tree detection. However, the large number of object categories and occlusion from nearby objects in complex environment pose great challenges in urban tree inventory, resulting in omission or commission errors. Therefore, this paper addresses these challenges and increases the accuracy of individual tree segmentation by proposing an automated method for instance recognition urban roadside trees. The proposed algorithm was implemented of unmanned aerial vehicles laser scanning (UAV-LS) data. First, an improved filtering algorithm was developed to identify ground and non-ground points. Second, we extracted tree-like objects via labeling on non-ground points using a deep learning model with a few smaller modifications. Unlike only concentrating on the global features in previous method, the proposed method revises a pointwise semantic learning network to capture both the global and local information at multiple scales, significantly avoiding the information loss in local neighborhoods and reducing useless convolutional computations. Afterwards, the semantic representation is fed into a graph-structured optimization model, which obtains globally optimal classification results by constructing a weighted indirect graph and solving the optimization problem with graph-cuts. The segmented tree points were extracted and consolidated through a series of operations, and they were finally recognized by combining graph embedding learning with a structure-aware loss function and a supervoxel-based normalized cut segmentation method. Experimental results on two public datasets demonstrated that our framework achieved better performance in terms of classification accuracy and recognition ratio of tree. Full article

(This article belongs to the Special Issue Advanced Research Based on Multi-Dimensional Point Cloud Analysis)

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15 pages, 4010 KiB

Open AccessEditor’s ChoiceTechnical Note

PolySimp: A Tool for Polygon Simplification Based on the Underlying Scaling Hierarchy

by Ding Ma, Zhigang Zhao, Ye Zheng, Renzhong Guo and Wei Zhu

ISPRS Int. J. Geo-Inf. 2020, 9(10), 594; https://doi.org/10.3390/ijgi9100594 - 10 Oct 2020

Cited by 6 | Viewed by 3556

Abstract

Map generalization is a process of reducing the contents of a map or data to properly show a geographic feature(s) at a smaller extent. Over the past few years, the fractal way of thinking has emerged as a new paradigm for map generalization. [...] Read more.

Map generalization is a process of reducing the contents of a map or data to properly show a geographic feature(s) at a smaller extent. Over the past few years, the fractal way of thinking has emerged as a new paradigm for map generalization. A geographic feature can be deemed as a fractal given the perspective of scaling, as its rough, irregular, and unsmooth shape inherently holds a striking scaling hierarchy of far more small elements than large ones. The pattern of far more small things than large ones is a de facto heavy tailed distribution. In this paper, we apply the scaling hierarchy for map generalization to polygonal features. To do this, we firstly revisit the scaling hierarchy of a classic fractal: the Koch Snowflake. We then review previous work that used the Douglas–Peuker algorithm, which identifies characteristic points on a line to derive three types of measures that are long-tailed distributed: the baseline length (d), the perpendicular distance to the baseline (x), and the area formed by x and d (area). More importantly, we extend the usage of the three measures to other most popular cartographical generalization methods; i.e., the bend simplify method, Visvalingam–Whyatt method, and hierarchical decomposition method, each of which decomposes any polygon into a set of bends, triangles, or convex hulls as basic geometric units for simplification. The different levels of details of the polygon can then be derived by recursively selecting the head part of geometric units and omitting the tail part using head/tail breaks, which is a new classification scheme for data with a heavy-tailed distribution. Since there are currently few tools with which to readily conduct the polygon simplification from such a fractal perspective, we have developed PolySimp, a tool that integrates the mentioned four algorithms for polygon simplification based on its underlying scaling hierarchy. The British coastline was selected to demonstrate the tool’s usefulness. The developed tool can be expected to showcase the applicability of fractal way of thinking and contribute to the development of map generalization. Full article

(This article belongs to the Special Issue Geographic Complexity: Concepts, Theories, and Practices)

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25 pages, 63671 KiB

Open AccessArticle

Spatio-Temporal Relationship between Land Cover and Land Surface Temperature in Urban Areas: A Case Study in Geneva and Paris

by Xu Ge, Dasaraden Mauree, Roberto Castello and Jean-Louis Scartezzini

ISPRS Int. J. Geo-Inf. 2020, 9(10), 593; https://doi.org/10.3390/ijgi9100593 - 10 Oct 2020

Cited by 15 | Viewed by 4427

Abstract

Currently, more than half of the world’s population lives in cities, which leads to major changes in land use and land surface temperature (LST). The associated urban heat island (UHI) effects have multiple impacts on energy consumption and human health. A better understanding [...] Read more.

Currently, more than half of the world’s population lives in cities, which leads to major changes in land use and land surface temperature (LST). The associated urban heat island (UHI) effects have multiple impacts on energy consumption and human health. A better understanding of how different land covers affect LST is necessary for mitigating adverse impacts, and supporting urban planning and public health management. This study explores a distance-based, a grid-based and a point-based analysis to investigate the influence of impervious surfaces, green area and waterbodies on LST, from large (distance and grid based analysis with 400 m grids) to smaller (point based analysis with 30 m grids) scale in the two mid-latitude cities of Paris and Geneva. The results at large scale confirm that the highest LST was observed in the city centers. A significantly positive correlation was observed between LST and impervious surface density. An anticorrelation between LST and green area density was observed in Paris. The spatial lag model was used to explore the spatial correlation among LST, NDBI, NDVI and MNDWI on a smaller scale. Inverse correlations between LST and NDVI and MNDWI, respectively, were observed. We conclude that waterbodies display the greatest mitigation on LST and UHI effects both on the large and smaller scale. Green areas play an important role in cooling effects on the smaller scale. An increase of evenly distributed green area and waterbodies in urban areas is suggested to lower LST and mitigate UHI effects. Full article

(This article belongs to the Special Issue Geodata Science and Spatial Analysis in Urban Studies)

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20 pages, 5248 KiB

Open AccessTechnical Note

Combining UAV Imagery, Volunteered Geographic Information, and Field Survey Data to Improve Characterization of Rural Water Points in Malawi

by Marc van den Homberg, Arjen Crince, Jurg Wilbrink, Daniël Kersbergen, Gumbi Gumbi, Simon Tembo and Rob Lemmens

ISPRS Int. J. Geo-Inf. 2020, 9(10), 592; https://doi.org/10.3390/ijgi9100592 - 9 Oct 2020

Cited by 4 | Viewed by 3803

Abstract

As the world is digitizing fast, the increase in Big and Small Data offers opportunities to enrich official statistics for reporting on Sustainable Development Goals (SDG). However, survey data coming from an increased number of organizations (Small Data) and Big Data offer challenges [...] Read more.

As the world is digitizing fast, the increase in Big and Small Data offers opportunities to enrich official statistics for reporting on Sustainable Development Goals (SDG). However, survey data coming from an increased number of organizations (Small Data) and Big Data offer challenges in terms of data heterogeneity. This paper describes a methodology for combining various data sources to create a more comprehensive dataset on SDG 6.1.1. (proportion of population using safely managed drinking water services). We enabled digital volunteers to trace buildings on satellite imagery and used the traces on OpenStreetMap to facilitate visual detection of water points on Unmanned Aerial Vehicle (UAV) imagery and estimate the number of people served per water point. Combining data on water points identified on our UAV imagery with data on water points from field surveys improves the overall quality in terms of removal of inconsistencies and enrichment of attribute information. Satellite imagery enables scaling more easily than UAV imagery but is too costly to acquire at sufficiently high resolution. For small areas, our workflow is cost-effective in creating an up-to-date and consistent water point dataset by combining UAV imagery, Volunteered Geographic Information, and field survey data. Full article

(This article belongs to the Special Issue Measuring and Monitoring Progress towards SDGs by Integrating Geospatial and Statistical Information)

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10 pages, 851 KiB

Open AccessReview

Usability of IoT and Open Data Repositories for Analyzing Water Pollution. A Case Study in the Czech Republic

by Jan Pavlík, Markéta Hrnčírová, Michal Stočes, Jan Masner and Jiří Vaněk

ISPRS Int. J. Geo-Inf. 2020, 9(10), 591; https://doi.org/10.3390/ijgi9100591 - 8 Oct 2020

Cited by 2 | Viewed by 2574

Abstract

Recently, the process of data opening has intensified, especially thanks to the involvement of many institutions that have not yet shared their data. Some entities provided data to the public long before the trend of open data was pushed to a wider level, [...] Read more.

Recently, the process of data opening has intensified, especially thanks to the involvement of many institutions that have not yet shared their data. Some entities provided data to the public long before the trend of open data was pushed to a wider level, but many institutions have only engaged in this process recently thanks to a systemic state-level effort to make data repositories available to the public. Therefore, there are many new potential sources of data available for research, including the area of water management. This article analyses the current state of available data in the Czech Republic—their content, structure, format, availability, costs and other indicators that affect the usability of these data for independent researchers in the area of water management. The case study was conducted to ascertain the levels of accessibility and usability of data in open data repositories and the possibilities of obtaining data from IoT (Internet of Things) devices such as networked sensors where required data is either not available from existing sources, too costly, or otherwise unsuitable for the research. The goal of the underlying research was to assess the impact/ratio of various watershed factors based on monitored indicators of water pollution in a model watershed. Such information would help propose measures for reducing the volume of pollution resulting in increased security in terms of available drinking water for the capital city Prague. Full article

(This article belongs to the Special Issue Integrating GIS and Internet of Things (IoT) in Sustainable Cities)

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34 pages, 9315 KiB

Open AccessEditor’s ChoiceArticle

A Comparative Study of Several Metaheuristic Algorithms to Optimize Monetary Incentive in Ridesharing Systems

by Fu-Shiung Hsieh

ISPRS Int. J. Geo-Inf. 2020, 9(10), 590; https://doi.org/10.3390/ijgi9100590 - 8 Oct 2020

Cited by 27 | Viewed by 3154

Abstract

The strong demand on human mobility leads to excessive numbers of cars and raises the problems of serious traffic congestion, large amounts of greenhouse gas emissions, air pollution and insufficient parking space in cities. Although ridesharing is a potential transport mode to solve [...] Read more.

The strong demand on human mobility leads to excessive numbers of cars and raises the problems of serious traffic congestion, large amounts of greenhouse gas emissions, air pollution and insufficient parking space in cities. Although ridesharing is a potential transport mode to solve the above problems through car-sharing, it is still not widely adopted. Most studies consider non-monetary incentive performance indices such as travel distance and successful matches in ridesharing systems. These performance indices fail to provide a strong incentive for ridesharing. The goal of this paper is to address this issue by proposing a monetary incentive performance indicator to improve the incentives for ridesharing. The objectives are to improve the incentive for ridesharing through a monetary incentive optimization problem formulation, development of a solution methodology and comparison of different solution algorithms. A non-linear integer programming optimization problem is formulated to optimize monetary incentive in ridesharing systems. Several discrete metaheuristic algorithms are developed to cope with computational complexity for solving the above problem. These include several discrete variants of particle swarm optimization algorithms, differential evolution algorithms and the firefly algorithm. The effectiveness of applying the above algorithms to solve the monetary incentive optimization problem is compared based on experimental results. Full article

(This article belongs to the Special Issue GIS in Sustainable Transportation)

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15 pages, 2567 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of the Space Syntax Measures Affecting Pedestrian Density through Ordinal Logistic Regression Analysis

by Özge Öztürk Hacar, Fatih Gülgen and Serdar Bilgi

ISPRS Int. J. Geo-Inf. 2020, 9(10), 589; https://doi.org/10.3390/ijgi9100589 - 7 Oct 2020

Cited by 8 | Viewed by 4154

Abstract

This paper examines the relationship between pedestrian density and space syntax measures in a university campus using ordinal logistic regression analysis. The pedestrian density assumed as the dependent variable of regression analysis was categorised in low, medium, and high classes by using Jenks [...] Read more.

This paper examines the relationship between pedestrian density and space syntax measures in a university campus using ordinal logistic regression analysis. The pedestrian density assumed as the dependent variable of regression analysis was categorised in low, medium, and high classes by using Jenks natural break classification. The data elements of groups were derived from pedestrian counts performed in 22 gates 132 times. The counting period grouped in nominal categories was assumed as an independent variable. Another independent was one of the 15 derived measures of axial analysis and visual graphic analysis. The statistically significant model results indicated that the integration of axial analysis was the most reasonable measure that explained the pedestrian density. Then, the changes in integration values of current and master plan datasets were analysed using paired sample t-test. The calculated p-value of t-test proved that the master plan would change the campus morphology for pedestrians. Full article

(This article belongs to the Special Issue Measuring, Mapping, Modeling, and Visualization of Cities)

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30 pages, 20417 KiB

Open AccessEditor’s ChoiceArticle

A Built Heritage Information System Based on Point Cloud Data: HIS-PC

by Florent Poux, Roland Billen, Jean-Paul Kasprzyk, Pierre-Henri Lefebvre and Pierre Hallot

ISPRS Int. J. Geo-Inf. 2020, 9(10), 588; https://doi.org/10.3390/ijgi9100588 - 7 Oct 2020

Cited by 17 | Viewed by 4568

Abstract

The digital management of an archaeological site requires to store, organise, access and represent all the information that is collected on the field. Heritage building information modelling, archaeological or heritage information systems now tend to propose a common framework where all the materials [...] Read more.

The digital management of an archaeological site requires to store, organise, access and represent all the information that is collected on the field. Heritage building information modelling, archaeological or heritage information systems now tend to propose a common framework where all the materials are managed from a central database and visualised through a 3D representation. In this research, we offer the development of a built heritage information system prototype based on a high-resolution 3D point cloud data set. The particularity of the approach is to consider a user-centred development methodology while avoiding meshing/down-sampling operations. The proposed system is initiated by a close collaboration between multi-modal users (managers, visitors, curators) and a development team (designers, developers, architects). The developed heritage information system permits the management of spatial and temporal information, including a wide range of semantics using relational along with NoSQL databases. The semantics used to describe the artifacts are subject to conceptual modelling. Finally, the system proposes a bi-directional communication with a 3D interface able to stream massive point clouds, which is a big step forward to provide a comprehensive site representation for stakeholders while minimising modelling costs. Full article

(This article belongs to the Special Issue BIM for Cultural Heritage (HBIM))

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18 pages, 4627 KiB

Open AccessArticle

A Machine Learning-Based Approach for Spatial Estimation Using the Spatial Features of Coordinate Information

by Seongin Ahn, Dong-Woo Ryu and Sangho Lee

ISPRS Int. J. Geo-Inf. 2020, 9(10), 587; https://doi.org/10.3390/ijgi9100587 - 6 Oct 2020

Cited by 10 | Viewed by 3558

Abstract

With the development of machine learning technology, research cases for spatial estimation through machine learning approach (MLA) in addition to the traditional geostatistical techniques are increasing. MLA has the advantage that spatial estimation is possible without stationary hypotheses of data, but it is [...] Read more.

With the development of machine learning technology, research cases for spatial estimation through machine learning approach (MLA) in addition to the traditional geostatistical techniques are increasing. MLA has the advantage that spatial estimation is possible without stationary hypotheses of data, but it is possible for the prediction results to ignore spatial autocorrelation. In recent studies, it was considered by using a distance matrix instead of raw coordinates. Although, the performance of spatial estimation could be improved through this approach, the computational complexity of MLA increased rapidly as the number of sample points increased. In this study, we developed a method to reduce the computational complexity of MLA while considering spatial autocorrelation. Principal component analysis is applied to it for extracting spatial features and reducing dimension of inputs. To verify the proposed approach, indicator Kriging was used as a benchmark model, and each performance of MLA was compared when using raw coordinates, distance vector, and spatial features extracted from distance vector as inputs. The proposed approach improved the performance compared to previous MLA and showed similar performance compared with Kriging. We confirmed that extracted features have characteristics of rigid classification in spatial estimation; on this basis, we conclude that the model could improve performance. Full article

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14 pages, 5131 KiB

Open AccessArticle

Urban Green Accessibility Index: A Measure of Pedestrian-Centered Accessibility to Every Green Point in an Urban Area

by Kee Moon Jang, Jaeman Kim, Hye-Yeong Lee, Hyemin Cho and Youngchul Kim

ISPRS Int. J. Geo-Inf. 2020, 9(10), 586; https://doi.org/10.3390/ijgi9100586 - 6 Oct 2020

Cited by 17 | Viewed by 6217

Abstract

Advancements in remote sensing techniques and urban data analysis tools have enabled the successful monitoring and detection of green spaces in a city. This study aims to develop an index called the urban green accessibility (UGA) index, which measures people’s accessibility to green [...] Read more.

Advancements in remote sensing techniques and urban data analysis tools have enabled the successful monitoring and detection of green spaces in a city. This study aims to develop an index called the urban green accessibility (UGA) index, which measures people’s accessibility to green space and represents the citywide or local characteristics of the distribution pattern of green space. The index is defined as the sum of pedestrians’ accessibility to all vegetation points, which consists of the normalized difference vegetation index (NDVI) with integration and choice values from angular segment analysis. In this study, the proposed index is tested with cases of New York, NY, and San Francisco, CA, in the US. The results reveal differences based on the significance of streets. When analysis ranges are on a neighborhood scale, a few hotspots appear in well-known green areas on commonly accessible streets and in local neighborhood parks on residential blocks. The appearance of high-accessibility points in low-NDVI areas implies the potential of the efficient and proper distribution of green spaces for pedestrians. The proposed measure is expected to help in planning and managing green areas in cities, taking people’s accessibility and spatial relationships into consideration. Full article

(This article belongs to the Special Issue Geodata Science and Spatial Analysis in Urban Studies)

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17 pages, 6506 KiB

Open AccessArticle

Measuring Spatial Accessibility of Urban Fire Services Using Historical Fire Incidents in Nanjing, China

by Kainan Mao, Yuehong Chen, Guohao Wu, Junwang Huang, Wanying Yang and Zelong Xia

ISPRS Int. J. Geo-Inf. 2020, 9(10), 585; https://doi.org/10.3390/ijgi9100585 - 6 Oct 2020

Cited by 17 | Viewed by 3449

Abstract

The measurement of spatial accessibility of fire services is a key task in enhancing fire response efficiency and minimizing property losses and deaths. Recently, the two-step floating catchment area method and its modified versions have been widely applied. However, the circle catchment areas [...] Read more.

The measurement of spatial accessibility of fire services is a key task in enhancing fire response efficiency and minimizing property losses and deaths. Recently, the two-step floating catchment area method and its modified versions have been widely applied. However, the circle catchment areas used in these methods are not suitable for measuring the accessibility of fire services because each fire station is often responsible for the fire incidents within its coverage. Meanwhile, most existing methods take the demographic data and their centroids of residential areas as the demands and locations, respectively, which makes it difficult to reflect the actual demands and locations of fire services. Thus, this paper proposes a fixed-coverage-based two-step floating catchment area (FC2SFCA) method that takes the fixed service coverage of fire stations as the catchment area and the locations and dispatched fire engines of historical fire incidents as the demand location and size, respectively, to measure the spatial accessibility of fire services. Using a case study area in Nanjing, China, the proposed FC2SFCA and enhanced two-step floating catchment area (E2SFCA) are employed to measure and compare the spatial accessibility of fire incidents and fire stations. The results show that (1) the spatial accessibility across Nanjing, China is unbalanced, with relatively high spatial accessibility in the areas around fire stations and the southwest and northeast at the city center area and relatively low spatial accessibility in the periphery and boundary of the service coverage areas and the core of the city center; (2) compared with E2SFCA, FC2SFCA is less influenced by other fire stations and provides greater actual fire service accessibility; (3) the spatial accessibility of fire services is more strongly affected by the number of fire incidents than firefighting capabilities, the area of service coverage, or the average number of crossroads (per kilometer). Suggestions are then made to improve the overall spatial access to fire services. Full article

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25 pages, 11279 KiB

Open AccessArticle

ADAtools: Automatic Detection and Classification of Active Deformation Areas from PSI Displacement Maps

by J. A. Navarro, R. Tomás, A. Barra, J. I. Pagán, C. Reyes-Carmona, L. Solari, J. L. Vinielles, S. Falco and M. Crosetto

ISPRS Int. J. Geo-Inf. 2020, 9(10), 584; https://doi.org/10.3390/ijgi9100584 - 6 Oct 2020

Cited by 30 | Viewed by 4123

Abstract

This work describes the set of tools developed, tested, and put into production in the context of the H2020 project Multi-scale Observation and Monitoring of Railway Infrastructure Threats (MOMIT). This project, which ended in 2019, aimed to show how the use of various [...] Read more.

This work describes the set of tools developed, tested, and put into production in the context of the H2020 project Multi-scale Observation and Monitoring of Railway Infrastructure Threats (MOMIT). This project, which ended in 2019, aimed to show how the use of various remote sensing techniques could help to improve the monitoring of railway infrastructures, such as tracks or bridges, and thus, consequently, improve the detection of ground instabilities and facilitate their management. Several lines of work were opened by MOMIT, but the authors of this work concentrated their efforts in the design of tools to help the detection and identification of ground movements using synthetic aperture radar interferometry (InSAR) data. The main output of this activity was a set of tools able to detect the areas labelled active deformation areas (ADA), with the highest deformation rates and to connect them to a geological or anthropogenic process. ADAtools is the name given to the aforementioned set of tools. The description of these tools includes the definition of their targets, inputs, and outputs, as well as details on how the correctness of the applications was checked and on the benchmarks showing their performance. The ADAtools include the following applications: ADAfinder, los2hv, ADAclassifier, and THEXfinder. The toolset is targeted at the analysis and interpretation of InSAR results. Ancillary information supports the semi-automatic interpretation and classification process. Two real use-cases illustrating this statement are included at the end of this paper to show the kind of results that may be obtained with the ADAtools. Full article

(This article belongs to the Special Issue Selected Papers from the International Conference on Geographical Information Systems Theory, Applications and Management (GISTAM 2020))

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16 pages, 3746 KiB

Open AccessArticle

Multitemporal Analysis of Deforestation in Response to the Construction of the Tucuruí Dam

by Andres Velastegui-Montoya, Aline de Lima and Marcos Adami

ISPRS Int. J. Geo-Inf. 2020, 9(10), 583; https://doi.org/10.3390/ijgi9100583 - 3 Oct 2020

Cited by 26 | Viewed by 5735

Abstract

The expansion of hydroelectric dams that is planned, and under construction, in the Amazon basin is a proposal to generate “clean” energy, with the purposes of meeting the regional energy demand, and the insertion of Brazil into the international economic market. However, this [...] Read more.

The expansion of hydroelectric dams that is planned, and under construction, in the Amazon basin is a proposal to generate “clean” energy, with the purposes of meeting the regional energy demand, and the insertion of Brazil into the international economic market. However, this type of megaproject can change the dynamics of natural ecosystems. In the present article, the spatiotemporal patterns of deforestation according to distance from the reservoir in the vicinity of the lake of Tucuruí, and within a radius of 30 km from it, are analyzed. A linear spectral mixture model of segmented Landsat-thematic mapper (TM), enhanced thematic mapper plus (ETM+), and operational land imager (OLI) images, and proximity analysis were used for the mapping of the land-cover classes in the vicinity of the artificial lake of Tucuruí. Likewise, landscape metrics were determined with the purpose of quantifying the reduction of primary forest, as a mechanism of loss of ecosystem services in the region. These methods were also used for the evaluation of the influence of the distance from the reservoir on the expansion of anthropogenic activities. This methodology was used for the scenarios of pre-inauguration, completion of phase I, beginning of construction phase II, full completion of the Tucuruí hydroelectric project, and the current scenario of the region. The results showed that the highest deforestation rate occurred in the first period of the analysis, due to the areas submerged by the reservoir and due to the anthropogenic disturbances, such as timber extraction, road construction, and the conversion of forests into large areas of agribusiness. Full article

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ISPRS Int. J. Geo-Inf., Volume 9, Issue 10 (October 2020) – 55 articles

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