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Volume 10
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ISPRS Int. J. Geo-Inf., Volume 10, Issue 2 (February 2021) – 63 articles

Cover Story (view full-size image): Crowdsourcing is widely used for air pollution monitoring with low-cost sensors measuring particulate matter concentration. We introduced social innovation into the air quality assessment area, which is based on citizen-driven air pollution symptom mapping (APSM). With this method, the citizens report their health symptoms related to air quality. They use the mobile survey app incorporated into GeoWeb, presenting the collected data in real time. The main challenge of the crowdsourcing method is unstructured data. Thus, we proposed the data quality assessment (QA) framework for health-symptom-based projects. It consists of several logic-based QA mechanisms implemented into GeoWeb, which make up a QA system reducing data bias. This way, citizens are engaged in creating a spatial model of city wellbeing which is consistent and reliable. View this paper
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26 pages, 10594 KiB  
Article
A Zonal Displacement Approach via Grid Point Weighting in Building Generalization
by Kadir Sahbaz and Melih Basaraner
ISPRS Int. J. Geo-Inf. 2021, 10(2), 105; https://doi.org/10.3390/ijgi10020105 - 23 Feb 2021
Cited by 5 | Viewed by 2290
Abstract
When generalizing a group of objects, displacement is an essential operation to resolve the conflicts arising between them due to enlargement of their symbol sizes and reduction of available map space. Although there are many displacement methods, most of them are rather complicated. [...] Read more.
When generalizing a group of objects, displacement is an essential operation to resolve the conflicts arising between them due to enlargement of their symbol sizes and reduction of available map space. Although there are many displacement methods, most of them are rather complicated. Therefore, more practical methods are still needed. In this article, a new building displacement approach is proposed. For this purpose, buildings are grouped and zones are created for them in the blocks via Voronoi tessellation and buffering. Linear patterns are then detected through buffer analyses and the respective zones are narrowed to be able to preserve these patterns. After all the buildings are displaced inside their zones, grid points are generated and then weighted through kernel density estimation and buffer analyses to find suitable locations. Accordingly, the buildings are displaced toward the computed locations iteratively. The proposed approach directly enforces minimum distance and positional accuracy constraints while several indirect mechanisms are used for preserving spatial patterns and relationships. For the quality evaluation of the displacement, the angle, length and shape comparison measures are introduced, computed based on the (Delaunay) triangles or the azimuth comparison measure of the connection lines, generated for the buildings. The quality evaluation criteria are yielded according to the visual assessment of the displacement quality and the quantitative analysis of the measures. The findings demonstrate that the proposed approach is quite effective and practical for zonal building displacement. Full article
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18 pages, 9023 KiB  
Article
Modeling of the German Wind Power Production with High Spatiotemporal Resolution
by Reinhold Lehneis, David Manske and Daniela Thrän
ISPRS Int. J. Geo-Inf. 2021, 10(2), 104; https://doi.org/10.3390/ijgi10020104 - 23 Feb 2021
Cited by 9 | Viewed by 4528
Abstract
Wind power has risen continuously over the last 20 years and covered almost 25% of the total German power provision in 2019. To investigate the effects and challenges of increasing wind power on energy systems, spatiotemporally disaggregated data on the electricity production from [...] Read more.
Wind power has risen continuously over the last 20 years and covered almost 25% of the total German power provision in 2019. To investigate the effects and challenges of increasing wind power on energy systems, spatiotemporally disaggregated data on the electricity production from wind turbines are often required. The lack of freely accessible feed-in time series from onshore turbines, e.g., due to data protection regulations, makes it necessary to determine the power generation for a certain region and period with the help of numerical simulations using publicly available plant and weather data. For this, a new approach is used for the wind power model which utilizes a sixth-order polynomial for the specific power curve of a turbine. After model validation with measured data from a single wind turbine, the simulations are carried out for an ensemble of 25,835 onshore turbines to determine the German wind power production for 2016. The resulting hourly resolved data are aggregated into a time series with daily resolution and compared with measured feed-in data of entire Germany which show a high degree of agreement. Such electricity generation data from onshore turbines can be applied to optimize and monitor renewable power systems on various spatiotemporal scales. Full article
(This article belongs to the Collection Spatial and Temporal Modelling of Renewable Energy Systems)
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17 pages, 4893 KiB  
Article
Escaping from Cities during the COVID-19 Crisis: Using Mobile Phone Data to Trace Mobility in Finland
by Elias Willberg, Olle Järv, Tuomas Väisänen and Tuuli Toivonen
ISPRS Int. J. Geo-Inf. 2021, 10(2), 103; https://doi.org/10.3390/ijgi10020103 - 23 Feb 2021
Cited by 74 | Viewed by 7382
Abstract
The coronavirus disease 2019 (COVID-19) crisis resulted in unprecedented changes in the spatial mobility of people across societies due to the restrictions imposed. This also resulted in unexpected mobility and population dynamics that created a challenge for crisis preparedness, including the mobility from [...] Read more.
The coronavirus disease 2019 (COVID-19) crisis resulted in unprecedented changes in the spatial mobility of people across societies due to the restrictions imposed. This also resulted in unexpected mobility and population dynamics that created a challenge for crisis preparedness, including the mobility from cities during the crisis due to the underlying phenomenon of multi-local living. People changing their residences can spread the virus between regions and create situations in which health and emergency services are not prepared for the population increase. Here, our focus is on urban–rural mobility and the influence of multi-local living on population dynamics in Finland during the COVID-19 crisis in 2020. Results, based on three mobile phone datasets, showed a significant drop in inter-municipal mobility and a shift in the presence of people—a population decline in urban centres and an increase in rural areas, which is strongly correlated to secondary housing. This study highlights the need to improve crisis preparedness by: (1) acknowledging the growing importance of multi-local living, and (2) improving the use of novel data sources for monitoring population dynamics and mobility. Mobile phone data products have enormous potential, but attention should be paid to the varying methodologies and their possible impact on analysis. Full article
(This article belongs to the Special Issue Geospatial Approaches for Understanding the Social, Economic and Environmental Impacts of COVID-19)
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23 pages, 6357 KiB  
Article
Machine Learning-Based Processing Proof-of-Concept Pipeline for Semi-Automatic Sentinel-2 Imagery Download, Cloudiness Filtering, Classifications, and Updates of Open Land Use/Land Cover Datasets
by Tomáš Řezník, Jan Chytrý and Kateřina Trojanová
ISPRS Int. J. Geo-Inf. 2021, 10(2), 102; https://doi.org/10.3390/ijgi10020102 - 23 Feb 2021
Cited by 7 | Viewed by 4005
Abstract
Land use and land cover are continuously changing in today’s world. Both domains, therefore, have to rely on updates of external information sources from which the relevant land use/land cover (classification) is extracted. Satellite images are frequent candidates due to their temporal and [...] Read more.
Land use and land cover are continuously changing in today’s world. Both domains, therefore, have to rely on updates of external information sources from which the relevant land use/land cover (classification) is extracted. Satellite images are frequent candidates due to their temporal and spatial resolution. On the contrary, the extraction of relevant land use/land cover information is demanding in terms of knowledge base and time. The presented approach offers a proof-of-concept machine-learning pipeline that takes care of the entire complex process in the following manner. The relevant Sentinel-2 images are obtained through the pipeline. Later, cloud masking is performed, including the linear interpolation of merged-feature time frames. Subsequently, four-dimensional arrays are created with all potential training data to become a basis for estimators from the scikit-learn library; the LightGBM estimator is then used. Finally, the classified content is applied to the open land use and open land cover databases. The verification of the provided experiment was conducted against detailed cadastral data, to which Shannon’s entropy was applied since the number of cadaster information classes was naturally consistent. The experiment showed a good overall accuracy (OA) of 85.9%. It yielded a classified land use/land cover map of the study area consisting of 7188 km2 in the southern part of the South Moravian Region in the Czech Republic. The developed proof-of-concept machine-learning pipeline is replicable to any other area of interest so far as the requirements for input data are met. Full article
(This article belongs to the Special Issue Advances in Machine Learning and Statistical Analysis of Geographical Data)
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22 pages, 5778 KiB  
Article
Artificial Neural Network Model Development to Predict Theft Types in Consideration of Environmental Factors
by Eunseo Kwon, Sungwon Jung and Jaewook Lee
ISPRS Int. J. Geo-Inf. 2021, 10(2), 99; https://doi.org/10.3390/ijgi10020099 - 22 Feb 2021
Cited by 4 | Viewed by 3515
Abstract
Crime prediction research using AI has been actively conducted to predict potential crimes—generally, crime locations or time series flows. It is possible to predict these potential crimes in detail if crime characteristics, such as detailed techniques, targets, and environmental factors affecting the crime’s [...] Read more.
Crime prediction research using AI has been actively conducted to predict potential crimes—generally, crime locations or time series flows. It is possible to predict these potential crimes in detail if crime characteristics, such as detailed techniques, targets, and environmental factors affecting the crime’s occurrence, are considered simultaneously. Therefore, this study aims to categorize theft by performing k-modes clustering using crime-related characteristics as variables and to propose an ANN model that predicts the derived categorizations. As the prediction of theft types allows people to estimate the features of the possibly most frequent thefts in random areas in advance, it enables the efficient deployment of police and the most appropriate tactical measures. Dongjak District was selected as the target area for analysis; thefts in the district showed four types of clusters. Environmental factors, representative elements affecting theft occurrence, were used as input data for a prediction model, while the factors affecting each cluster were derived through multiple linear regression analysis. Based on the results, input variables were selected for the ANN model training per cluster, and the model was implemented to predict theft type based on environmental factors. This study is significant for providing diversity to prediction methods using ANN. Full article
(This article belongs to the Special Issue Geo-Information Science in Planning and Development of Smart Cities)
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20 pages, 6694 KiB  
Article
Passive Mobile Data for Studying Seasonal Tourism Mobilities: An Application in a Mediterranean Coastal Destination
by Benito Zaragozí, Sergio Trilles and Aaron Gutiérrez
ISPRS Int. J. Geo-Inf. 2021, 10(2), 98; https://doi.org/10.3390/ijgi10020098 - 22 Feb 2021
Cited by 11 | Viewed by 3954
Abstract
The article uses passive mobile data to analyse the complex mobilities that occur in a coastal region characterised by seasonal patterns of tourism activity. A large volume of data generated by mobile phone users has been selected and processed to subsequently display the [...] Read more.
The article uses passive mobile data to analyse the complex mobilities that occur in a coastal region characterised by seasonal patterns of tourism activity. A large volume of data generated by mobile phone users has been selected and processed to subsequently display the information in the form of visualisations that are useful for transport and tourism research, policy, and practice. More specifically, the analysis consisted of four steps: (1) a dataset containing records for four days—two on summer days and two in winter—was selected, (2) these were aggregated spatially, temporally, and differentiating trips by local residents, national tourists, and international tourists, (3) origin-destination matrices were built, and (4) graph-based visualisations were created to provide evidence on the nature of the mobilities affecting the study area. The results of our work provide new evidence of how the analysis of passive mobile data can be useful to study the effects of tourism seasonality in local mobility patterns. Full article
(This article belongs to the Special Issue Advances in Social Network Analysis – Spatio-Temporal and Semantic Methods)
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17 pages, 1234 KiB  
Article
Framework for Indoor Elements Classification via Inductive Learning on Floor Plan Graphs
by Jaeyoung Song and Kiyun Yu
ISPRS Int. J. Geo-Inf. 2021, 10(2), 97; https://doi.org/10.3390/ijgi10020097 - 22 Feb 2021
Cited by 11 | Viewed by 4601
Abstract
This paper presents a new framework to classify floor plan elements and represent them in a vector format. Unlike existing approaches using image-based learning frameworks as the first step to segment the image pixels, we first convert the input floor plan image into [...] Read more.
This paper presents a new framework to classify floor plan elements and represent them in a vector format. Unlike existing approaches using image-based learning frameworks as the first step to segment the image pixels, we first convert the input floor plan image into vector data and utilize a graph neural network. Our framework consists of three steps. (1) image pre-processing and vectorization of the floor plan image; (2) region adjacency graph conversion; and (3) the graph neural network on converted floor plan graphs. Our approach is able to capture different types of indoor elements including basic elements, such as walls, doors, and symbols, as well as spatial elements, such as rooms and corridors. In addition, the proposed method can also detect element shapes. Experimental results show that our framework can classify indoor elements with an F1 score of 95%, with scale and rotation invariance. Furthermore, we propose a new graph neural network model that takes the distance between nodes into account, which is a valuable feature of spatial network data. Full article
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17 pages, 4899 KiB  
Article
Mini-Map for Gamers Who Walk and Teleport in a Virtual Stronghold
by Krzysztof Zagata, Jacek Gulij, Łukasz Halik and Beata Medyńska-Gulij
ISPRS Int. J. Geo-Inf. 2021, 10(2), 96; https://doi.org/10.3390/ijgi10020096 - 22 Feb 2021
Cited by 39 | Viewed by 6246
Abstract
Studies of the effectiveness of multimedia cartography products may include mini-map design for navigation. In this study, we have touched upon designing gameplay to indicate the impact of the mini-map on the time effectiveness of a player that can walk or teleport himself/herself [...] Read more.
Studies of the effectiveness of multimedia cartography products may include mini-map design for navigation. In this study, we have touched upon designing gameplay to indicate the impact of the mini-map on the time effectiveness of a player that can walk or teleport himself/herself along marked out points in virtual topographic space. The eye-tracking examination of gamers’ effectiveness in a non-complex game of collecting coins in a reconstructed stronghold on the holm provided us with a new perspective on the role of mini-maps. The more time gamers took to examine the mini-map, the more time they needed to finish the game, thus decreasing their effectiveness. The teleporting gamers had significantly higher time effectiveness than walking gamers, however, the data obtained showed only a minor difference between the proportions of the mini-map examination time to the total game time for walking and teleportation. Full article
(This article belongs to the Special Issue Multimedia Cartography)
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16 pages, 5644 KiB  
Article
Urban Growth, Real Estate Development and Indigenous Property: Simulating the Expansion Process in the City of Temuco, Chile
by Francisco Maturana, Mauricio Morales, Fernando Peña-Cortés, Marco A. Peña and Carlos Vielma
ISPRS Int. J. Geo-Inf. 2021, 10(2), 101; https://doi.org/10.3390/ijgi10020101 - 22 Feb 2021
Cited by 6 | Viewed by 3678
Abstract
Urbanization is spreading across the world and beyond metropolitan areas. Medium-sized cities have also undergone processes of accelerated urban expansion, especially in Latin America, thanks to scant regulation or a complete lack thereof. Thus, understanding urban growth in the past and simulating it [...] Read more.
Urbanization is spreading across the world and beyond metropolitan areas. Medium-sized cities have also undergone processes of accelerated urban expansion, especially in Latin America, thanks to scant regulation or a complete lack thereof. Thus, understanding urban growth in the past and simulating it in the future has become a tool to raise its visibility and challenge territorial planners. In this work, we use Markov chains, cellular automata, multi-criteria multi-objective evaluation, and the determination of land use/land cover (LULC) to model the urban growth of the city of Temuco, Chile, a paradigmatic case because it has experienced powerful growth, where real estate development pressures coexist with a high natural value and the presence of indigenous communities. The urban scenario is determined for the years 2033 and 2049 based on the spatial patterns between 1985 and 2017, where the model shows the trend of expansion toward the northeast and significant development in the western sector of the city, making them two potential centers of expansion and conflict in the future given the heavy pressure on lands that are indigenous property and have a high natural value, aspects that need to be incorporated into future territorial planning instruments. Full article
(This article belongs to the Special Issue Spatio-Temporal Models and Geo-Technologies)
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21 pages, 6287 KiB  
Article
Practical Efficient Regional Land-Use Planning Using Constrained Multi-Objective Genetic Algorithm Optimization
by Tingting Pan, Yu Zhang, Fenzhen Su, Vincent Lyne, Fei Cheng and Han Xiao
ISPRS Int. J. Geo-Inf. 2021, 10(2), 100; https://doi.org/10.3390/ijgi10020100 - 22 Feb 2021
Cited by 25 | Viewed by 3225
Abstract
Practical efficient regional land-use planning requires planners to balance competing uses, regional policies, spatial compatibilities, and priorities across the social, economic, and ecological domains. Genetic algorithm optimization has progressed complex planning, but challenges remain in developing practical alternatives to random initialization, genetic mutations, [...] Read more.
Practical efficient regional land-use planning requires planners to balance competing uses, regional policies, spatial compatibilities, and priorities across the social, economic, and ecological domains. Genetic algorithm optimization has progressed complex planning, but challenges remain in developing practical alternatives to random initialization, genetic mutations, and to pragmatically balance competing objectives. To meet these practical needs, we developed a Land use Intensity-restricted Multi-objective Spatial Optimization (LIr-MSO) model with more realistic patch size initialization, novel mutation, elite strategies, and objectives balanced via nominalizations and weightings. We tested the model for Dapeng, China where experiments compared comprehensive fitness (across conversion cost, Gross Domestic Product (GDP), ecosystem services value, compactness, and conflict degree) with three contrast experiments, in which changes were separately made in the initialization and mutation. The comprehensive model gave superior fitness compared to the contrast experiments. Iterations progressed rapidly to near-optimality, but final convergence involved much slower parent–offspring mutations. Tradeoffs between conversion cost and compactness were strongest, and conflict degree improved in part as an emergent property of the spatial social connectedness built into our algorithm. Observations of rapid iteration to near-optimality with our model can facilitate interactive simulations, not possible with current models, involving land-use planners and regional managers. Full article
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19 pages, 1612 KiB  
Article
The Intensity of Urban Sprawl in Poland
by Piotr Lityński
ISPRS Int. J. Geo-Inf. 2021, 10(2), 95; https://doi.org/10.3390/ijgi10020095 - 21 Feb 2021
Cited by 29 | Viewed by 3866
Abstract
The issues of urban sprawl are current in both global research as well as the sphere of activities by public authorities in developed and developing countries. Urban sprawl is a phenomenon that goes beyond the administrative boundaries of cities, which forces monitoring of [...] Read more.
The issues of urban sprawl are current in both global research as well as the sphere of activities by public authorities in developed and developing countries. Urban sprawl is a phenomenon that goes beyond the administrative boundaries of cities, which forces monitoring of the phenomenon on a wide territorial scale, i.e., regional and national. However, assessing the level of urban sprawl on such a scale still remains a research challenge in many countries. Poland is such an example, where there is a deficit in assessing the level of the phenomenon, its spatial specificity, as well as comparisons between other national urban areas. The presented research uses the urban morphology method to assess urban sprawl in Poland. The method assumes the use of square grids and building locations for the quantification of sprawl. Based on the 14 urban areas that aggregate 296 communes, it was pointed out that the level of urban sprawl in Poland is moderate. The results indicate that there is not a significant sprawl or compact structures. Full article
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33 pages, 4090 KiB  
Review
Geoinformation Technologies in Support of Environmental Hazards Monitoring under Climate Change: An Extensive Review
by Andreas Tsatsaris, Kleomenis Kalogeropoulos, Nikolaos Stathopoulos, Panagiota Louka, Konstantinos Tsanakas, Demetrios E. Tsesmelis, Vassilios Krassanakis, George P. Petropoulos, Vasilis Pappas and Christos Chalkias
ISPRS Int. J. Geo-Inf. 2021, 10(2), 94; https://doi.org/10.3390/ijgi10020094 - 21 Feb 2021
Cited by 51 | Viewed by 7417
Abstract
Human activities and climate change constitute the contemporary catalyst for natural processes and their impacts, i.e., geo-environmental hazards. Globally, natural catastrophic phenomena and hazards, such as drought, soil erosion, quantitative and qualitative degradation of groundwater, frost, flooding, sea level rise, etc., are intensified [...] Read more.
Human activities and climate change constitute the contemporary catalyst for natural processes and their impacts, i.e., geo-environmental hazards. Globally, natural catastrophic phenomena and hazards, such as drought, soil erosion, quantitative and qualitative degradation of groundwater, frost, flooding, sea level rise, etc., are intensified by anthropogenic factors. Thus, they present rapid increase in intensity, frequency of occurrence, spatial density, and significant spread of the areas of occurrence. The impact of these phenomena is devastating to human life and to global economies, private holdings, infrastructure, etc., while in a wider context it has a very negative effect on the social, environmental, and economic status of the affected region. Geospatial technologies including Geographic Information Systems, Remote Sensing—Earth Observation as well as related spatial data analysis tools, models, databases, contribute nowadays significantly in predicting, preventing, researching, addressing, rehabilitating, and managing these phenomena and their effects. This review attempts to mark the most devastating geo-hazards from the view of environmental monitoring, covering the state of the art in the use of geospatial technologies in that respect. It also defines the main challenge of this new era which is nothing more than the fictitious exploitation of the information produced by the environmental monitoring so that the necessary policies are taken in the direction of a sustainable future. The review highlights the potential and increasing added value of geographic information as a means to support environmental monitoring in the face of climate change. The growth in geographic information seems to be rapidly accelerated due to the technological and scientific developments that will continue with exponential progress in the years to come. Nonetheless, as it is also highlighted in this review continuous monitoring of the environment is subject to an interdisciplinary approach and contains an amount of actions that cover both the development of natural phenomena and their catastrophic effects mostly due to climate change. Full article
(This article belongs to the Special Issue GIS-Based Analysis for Quality of Life and Environmental Monitoring)
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19 pages, 4581 KiB  
Article
A Novel Hybrid Method for Landslide Susceptibility Mapping-Based GeoDetector and Machine Learning Cluster: A Case of Xiaojin County, China
by Wei Xie, Xiaoshuang Li, Wenbin Jian, Yang Yang, Hongwei Liu, Luis F. Robledo and Wen Nie
ISPRS Int. J. Geo-Inf. 2021, 10(2), 93; https://doi.org/10.3390/ijgi10020093 - 20 Feb 2021
Cited by 92 | Viewed by 4707
Abstract
Landslide susceptibility mapping (LSM) could be an effective way to prevent landslide hazards and mitigate losses. The choice of conditional factors is crucial to the results of LSM, and the selection of models also plays an important role. In this study, a hybrid [...] Read more.
Landslide susceptibility mapping (LSM) could be an effective way to prevent landslide hazards and mitigate losses. The choice of conditional factors is crucial to the results of LSM, and the selection of models also plays an important role. In this study, a hybrid method including GeoDetector and machine learning cluster was developed to provide a new perspective on how to address these two issues. We defined redundant factors by quantitatively analyzing the single impact and interactive impact of the factors, which was analyzed by GeoDetector, the effect of this step was examined using mean absolute error (MAE). The machine learning cluster contains four models (artificial neural network (ANN), Bayesian network (BN), logistic regression (LR), and support vector machines (SVM)) and automatically selects the best one for generating LSM. The receiver operating characteristic (ROC) curve, prediction accuracy, and the seed cell area index (SCAI) methods were used to evaluate these methods. The results show that the SVM model had the best performance in the machine learning cluster with the area under the ROC curve of 0.928 and with an accuracy of 83.86%. Therefore, SVM was chosen as the assessment model to map the landslide susceptibility of the study area. The landslide susceptibility map demonstrated fit with landslide inventory, indicated the hybrid method is effective in screening landslide influences and assessing landslide susceptibility. Full article
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18 pages, 9964 KiB  
Technical Note
A Fine-Scale Mangrove Map of China Derived from 2-Meter Resolution Satellite Observations and Field Data
by Tao Zhang, Shanshan Hu, Yun He, Shucheng You, Xiaomei Yang, Yuhang Gan and Aixia Liu
ISPRS Int. J. Geo-Inf. 2021, 10(2), 92; https://doi.org/10.3390/ijgi10020092 - 20 Feb 2021
Cited by 34 | Viewed by 5113
Abstract
Mangrove forests are important ecosystems in the coastal intertidal zone, but China’s mangroves have experienced a large reduction in area from the 1950s, and the remaining mangrove forests are exhibiting increased fragmentation. A detailed mangrove dataset of China is crucial for mangrove ecosystem [...] Read more.
Mangrove forests are important ecosystems in the coastal intertidal zone, but China’s mangroves have experienced a large reduction in area from the 1950s, and the remaining mangrove forests are exhibiting increased fragmentation. A detailed mangrove dataset of China is crucial for mangrove ecosystem management and protection, but the fragmented mangrove patches are hardly mapped by medium resolution satellite imagery. To overcome these difficulties, we presented a fine-scale mangrove map for 2018 using the 2-meter resolution Gaofen-1 and Ziyuan-3 satellite imagery together with field data. We employed a hybrid method of object-based image analysis (OBIA), interpreter editing, and field surveying for mangrove mapping. The field survey route reached 9500 km, and 2650 patches were verified during the field work. Accuracy assessment by confusion matrix showed that the kappa coefficient reached 0.98, indicating a highly thematic accuracy of the mangrove dataset. Results showed the total area of mangrove forest in China for 2018 was 25,683.88 hectares, and approximately 91% of mangroves were found in the three provinces of Guangdong, Guangxi, and Hainan. About 64% of mangroves were distributed in or near the nature reserves established by national or local governments, which indicated that China’s mangroves were well protected in recent years. The new fine-scale mangrove dataset was freely shared together with this paper, and it can be used by local authorities and research groups for mangrove management and ecological planning. Full article
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32 pages, 23567 KiB  
Article
Production, Validation and Morphometric Analysis of a Digital Terrain Model for Lake Trichonis Using Geospatial Technologies and Hydroacoustics
by Triantafyllia-Maria Perivolioti, Antonios Mouratidis, Dimitrios Terzopoulos, Panagiotis Kalaitzis, Dimitrios Ampatzidis, Michal Tušer, Jaroslava Frouzova and Dimitra Bobori
ISPRS Int. J. Geo-Inf. 2021, 10(2), 91; https://doi.org/10.3390/ijgi10020091 - 20 Feb 2021
Cited by 1 | Viewed by 2637
Abstract
Covering an area of approximately 97 km2 and with a maximum depth of 58 m, Lake Trichonis is the largest and one of the deepest natural lakes in Greece. As such, it constitutes an important ecosystem and freshwater reserve at the regional [...] Read more.
Covering an area of approximately 97 km2 and with a maximum depth of 58 m, Lake Trichonis is the largest and one of the deepest natural lakes in Greece. As such, it constitutes an important ecosystem and freshwater reserve at the regional scale, whose qualitative and quantitative properties ought to be monitored. Depth is a crucial parameter, as it is involved in both qualitative and quantitative monitoring aspects. Thus, the availability of a bathymetric model and a reliable DTM (Digital Terrain Model) of such an inland water body is imperative for almost any systematic observation scenario or ad hoc measurement endeavor. In this context, the purpose of this study is to produce a DTM from the only official cartographic source of relevant information available (dating back approximately 70 years) and evaluate its performance against new, independent, high-accuracy hydroacoustic recordings. The validation procedure involves the use of echosoundings coupled with GPS, and is followed by the production of a bathymetric model for the assessment of the discrepancies between the DTM and the measurements, along with the relevant morphometric analysis. Both the production and validation of the DTM are conducted in a GIS environment. The results indicate substantial discrepancies between the old DTM and contemporary acoustic data. A significant overall deviation of 3.39 ± 5.26 m in absolute bottom elevation differences and 0.00 ± 7.26 m in relative difference residuals (0.00 ± 2.11 m after 2nd polynomial model corrector surface fit) of the 2019 bathymetric dataset with respect to the ~1950 lake DTM and overall morphometry appear to be associated with a combination of tectonics, subsidence and karstic phenomena in the area. These observations could prove useful for the tectonics, geodynamics and seismicity with respect to the broader Corinth Rift region, as well as for environmental management and technical interventions in and around the lake. This dictates the necessity for new, extensive bathymetric measurements in order to produce an updated DTM of Lake Trichonis, reflecting current conditions and tailored to contemporary accuracy standards and state-of-the-art research in various disciplines in and around the lake. Full article
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19 pages, 7155 KiB  
Article
A New Approach to Measuring the Similarity of Indoor Semantic Trajectories
by Jin Zhu, Dayu Cheng, Weiwei Zhang, Ci Song, Jie Chen and Tao Pei
ISPRS Int. J. Geo-Inf. 2021, 10(2), 90; https://doi.org/10.3390/ijgi10020090 - 20 Feb 2021
Cited by 7 | Viewed by 2525
Abstract
People spend more than 80% of their time in indoor spaces, such as shopping malls and office buildings. Indoor trajectories collected by indoor positioning devices, such as WiFi and Bluetooth devices, can reflect human movement behaviors in indoor spaces. Insightful indoor movement patterns [...] Read more.
People spend more than 80% of their time in indoor spaces, such as shopping malls and office buildings. Indoor trajectories collected by indoor positioning devices, such as WiFi and Bluetooth devices, can reflect human movement behaviors in indoor spaces. Insightful indoor movement patterns can be discovered from indoor trajectories using various clustering methods. These methods are based on a measure that reflects the degree of similarity between indoor trajectories. Researchers have proposed many trajectory similarity measures. However, existing trajectory similarity measures ignore the indoor movement constraints imposed by the indoor space and the characteristics of indoor positioning sensors, which leads to an inaccurate measure of indoor trajectory similarity. Additionally, most of these works focus on the spatial and temporal dimensions of trajectories and pay less attention to indoor semantic information. Integrating indoor semantic information such as the indoor point of interest into the indoor trajectory similarity measurement is beneficial to discovering pedestrians having similar intentions. In this paper, we propose an accurate and reasonable indoor trajectory similarity measure called the indoor semantic trajectory similarity measure (ISTSM), which considers the features of indoor trajectories and indoor semantic information simultaneously. The ISTSM is modified from the edit distance that is a measure of the distance between string sequences. The key component of the ISTSM is an indoor navigation graph that is transformed from an indoor floor plan representing the indoor space for computing accurate indoor walking distances. The indoor walking distances and indoor semantic information are fused into the edit distance seamlessly. The ISTSM is evaluated using a synthetic dataset and real dataset for a shopping mall. The experiment with the synthetic dataset reveals that the ISTSM is more accurate and reasonable than three other popular trajectory similarities, namely the longest common subsequence (LCSS), edit distance on real sequence (EDR), and the multidimensional similarity measure (MSM). The case study of a shopping mall shows that the ISTSM effectively reveals customer movement patterns of indoor customers. Full article
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20 pages, 9554 KiB  
Article
IdroGEO: A Collaborative Web Mapping Application Based on REST API Services and Open Data on Landslides and Floods in Italy
by Carla Iadanza, Alessandro Trigila, Paolo Starace, Alessio Dragoni, Tommaso Biondo and Marco Roccisano
ISPRS Int. J. Geo-Inf. 2021, 10(2), 89; https://doi.org/10.3390/ijgi10020089 - 20 Feb 2021
Cited by 35 | Viewed by 6527
Abstract
The new national IdroGEO web platform allows the navigation, social sharing and download of data, maps, reports of the Italian Landslide Inventory, national hazard maps, and risk indicators. It is a tool for communication and dissemination of information to support decisions in risk [...] Read more.
The new national IdroGEO web platform allows the navigation, social sharing and download of data, maps, reports of the Italian Landslide Inventory, national hazard maps, and risk indicators. It is a tool for communication and dissemination of information to support decisions in risk mitigation policies, land use planning, preliminary design of infrastructures, prioritization of mitigation measures, management of civil protection emergencies, and environmental impact assessment. The challenges that have been faced during the design and development of the platform concern usability, access on multiple devices (smartphones, tablets, desktops), interoperability, transparency, reuse of information and software in the public sector, and improvement of the updating of the Italian Landslide Inventory. The methodologies and solutions adopted to address them include Progressive Web Application (PWA), Application Programming Interface (API), open standards, open libraries, and software. A landslide inventory management system has been developed via REST API for data entry and approval workflow in order to maintain the inventory in a distributed and collaborative manner. As a result, IdroGEO provides a public service for citizens, public administration, and professionals, using the “mobile first” approach and with scalable and reliable architecture. IdroGEO represents a solid infrastructure for the interoperability of data that serves as the foundation for creating a first knowledge-graph on landslides and the community who manages them. Full article
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22 pages, 3044 KiB  
Article
Simulating Spatio-Temporal Patterns of Bicycle Flows with an Agent-Based Model
by Dana Kaziyeva, Martin Loidl and Gudrun Wallentin
ISPRS Int. J. Geo-Inf. 2021, 10(2), 88; https://doi.org/10.3390/ijgi10020088 - 20 Feb 2021
Cited by 14 | Viewed by 4227
Abstract
Transport planning strategies regard cycling promotion as a suitable means for tackling problems connected with motorized traffic such as limited space, congestion, and pollution. However, the evidence base for optimizing cycling promotion is weak in most cases, and information on bicycle patterns at [...] Read more.
Transport planning strategies regard cycling promotion as a suitable means for tackling problems connected with motorized traffic such as limited space, congestion, and pollution. However, the evidence base for optimizing cycling promotion is weak in most cases, and information on bicycle patterns at a sufficient resolution is largely lacking. In this paper, we propose agent-based modeling to simulate bicycle traffic flows at a regional scale level for an entire day. The feasibility of the model is demonstrated in a use case in the Salzburg region, Austria. The simulation results in distinct spatio-temporal bicycle traffic patterns at high spatial (road segments) and temporal (minute) resolution. Scenario analysis positively assesses the model’s level of complexity, where the demographically parametrized behavior of cyclists outperforms stochastic null models. Validation with reference data from three sources shows a high correlation between simulated and observed bicycle traffic, where the predictive power is primarily related to the quality of the input and validation data. In conclusion, the implemented agent-based model successfully simulates bicycle patterns of 186,000 inhabitants within a reasonable time. This spatially explicit approach of modeling individual mobility behavior opens new opportunities for evidence-based planning and decision making in the wide field of cycling promotion Full article
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35 pages, 6832 KiB  
Article
A Data Cube Metamodel for Geographic Analysis Involving Heterogeneous Dimensions
by Jean-Paul Kasprzyk and Guénaël Devillet
ISPRS Int. J. Geo-Inf. 2021, 10(2), 87; https://doi.org/10.3390/ijgi10020087 - 19 Feb 2021
Cited by 5 | Viewed by 4560
Abstract
Due to their multiple sources and structures, big spatial data require adapted tools to be efficiently collected, summarized and analyzed. For this purpose, data are archived in data warehouses and explored by spatial online analytical processing (SOLAP) through dynamic maps, charts and tables. [...] Read more.
Due to their multiple sources and structures, big spatial data require adapted tools to be efficiently collected, summarized and analyzed. For this purpose, data are archived in data warehouses and explored by spatial online analytical processing (SOLAP) through dynamic maps, charts and tables. Data are thus converted in data cubes characterized by a multidimensional structure on which exploration is based. However, multiple sources often lead to several data cubes defined by heterogeneous dimensions. In particular, dimensions definition can change depending on analyzed scale, territory and time. In order to consider these three issues specific to geographic analysis, this research proposes an original data cube metamodel defined in unified modeling language (UML). Based on concepts like common dimension levels and metadimensions, the metamodel can instantiate constellations of heterogeneous data cubes allowing SOLAP to perform multiscale, multi-territory and time analysis. Afterwards, the metamodel is implemented in a relational data warehouse and validated by an operational tool designed for a social economy case study. This tool, called “Racines”, gathers and compares multidimensional data about social economy business in Belgium and France through interactive cross-border maps, charts and reports. Thanks to the metamodel, users remain independent from IT specialists regarding data exploration and integration. Full article
(This article belongs to the Special Issue GIS Software and Engineering for Big Data)
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22 pages, 5627 KiB  
Article
Spatiotemporal Dynamics of Suspended Sediments in the Negro River, Amazon Basin, from In Situ and Sentinel-2 Remote Sensing Data
by Rogério Ribeiro Marinho, Tristan Harmel, Jean-Michel Martinez and Naziano Pantoja Filizola Junior
ISPRS Int. J. Geo-Inf. 2021, 10(2), 86; https://doi.org/10.3390/ijgi10020086 - 19 Feb 2021
Cited by 30 | Viewed by 4770
Abstract
Monitoring suspended sediments through remote sensing data in black-water rivers is a challenge. Herein, remote sensing reflectance (Rrs) from in situ measurements and Sentinel-2 Multi-Spectral Instrument (MSI) images were used to estimate the suspended sediment concentration (SSC) in the largest black-water [...] Read more.
Monitoring suspended sediments through remote sensing data in black-water rivers is a challenge. Herein, remote sensing reflectance (Rrs) from in situ measurements and Sentinel-2 Multi-Spectral Instrument (MSI) images were used to estimate the suspended sediment concentration (SSC) in the largest black-water river of the Amazon basin. The Negro River exhibits extremely low Rrs values (<0.005 sr−1 at visible and near-infrared bands) due to the elevated absorption of coloured dissolved organic matter (aCDOM at 440 nm > 7 m−1) caused by the high amount of dissolved organic carbon (DOC > 7 mg L−1) and low SSC (<5 mg L−1). Interannual variability of Rrs is primarily controlled by the input of suspended sediments from the Branco River, which is a clear water river that governs the changes in the apparent optical properties of the Negro River, even at distances that are greater than 90 km from its mouth. Better results were obtained using the Sentinel-2 MSI Red band (Band 4 at 665 nm) in order to estimate the SSC, with an R2 value greater than 0.85 and an error less than 20% in the adjusted models. The magnitudes of water reflectance in the Sentinel-2 MSI Red band were consistent with in situ Rrs measurements, indicating the large spatial variability of the lower SSC values (0 to 15 mg L−1) in a complex anabranching reach of the Negro River. The in situ and satellite data analysed in this study indicates sedimentation processes in the lower Negro River near the Amazon River. The results suggest that the radiometric characteristics of sensors, like sentinel-2 MSI, are suitable for monitoring the suspended sediment concentration in large tropical black-water rivers. Full article
(This article belongs to the Special Issue GIS and Remote Sensing Applications in Geomorphology)
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17 pages, 9586 KiB  
Article
Digital Graphic Documentation and Architectural Heritage: Deformations in a 16th-Century Ceiling of the Pinelo Palace in Seville (Spain)
by Juan Francisco Reinoso-Gordo, Antonio Gámiz-Gordo and Pedro Barrero-Ortega
ISPRS Int. J. Geo-Inf. 2021, 10(2), 85; https://doi.org/10.3390/ijgi10020085 - 19 Feb 2021
Cited by 10 | Viewed by 3589
Abstract
Suitable graphic documentation is essential to ascertain and conserve architectural heritage. For the first time, accurate digital images are provided of a 16th-century wooden ceiling, composed of geometric interlacing patterns, in the Pinelo Palace in Seville. Today, this ceiling suffers from significant deformation. [...] Read more.
Suitable graphic documentation is essential to ascertain and conserve architectural heritage. For the first time, accurate digital images are provided of a 16th-century wooden ceiling, composed of geometric interlacing patterns, in the Pinelo Palace in Seville. Today, this ceiling suffers from significant deformation. Although there are many publications on the digital documentation of architectural heritage, no graphic studies on this type of deformed ceilings have been presented. This study starts by providing data on the palace history concerning the design of geometric interlacing patterns in carpentry according to the 1633 book by López de Arenas, and on the ceiling consolidation in the 20th century. Images were then obtained using two complementary procedures: from a 3D laser scanner, which offers metric data on deformations; and from photogrammetry, which facilitates the visualisation of details. In this way, this type of heritage is documented in an innovative graphic approach, which is essential for its conservation and/or restoration with scientific foundations and also to disseminate a reliable digital image of the most beautiful ceiling of this Renaissance palace in southern Europe. Full article
(This article belongs to the Special Issue 3D Modeling and GIS for Historical Sites Reconstruction)
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18 pages, 3920 KiB  
Article
Spatial Variability of Rainfall Trends in Sri Lanka from 1989 to 2019 as an Indication of Climate Change
by Niranga Alahacoon and Mahesh Edirisinghe
ISPRS Int. J. Geo-Inf. 2021, 10(2), 84; https://doi.org/10.3390/ijgi10020084 - 19 Feb 2021
Cited by 61 | Viewed by 12230
Abstract
Analysis of long-term rainfall trends provides a wealth of information on effective crop planning and water resource management, and a better understanding of climate variability over time. This study reveals the spatial variability of rainfall trends in Sri Lanka from 1989 to 2019 [...] Read more.
Analysis of long-term rainfall trends provides a wealth of information on effective crop planning and water resource management, and a better understanding of climate variability over time. This study reveals the spatial variability of rainfall trends in Sri Lanka from 1989 to 2019 as an indication of climate change. The exclusivity of the study is the use of rainfall data that provide spatial variability instead of the traditional location-based approach. Henceforth, daily rainfall data available at Climate Hazards Group InfraRed Precipitation corrected with stations (CHIRPS) data were used for this study. The geographic information system (GIS) is used to perform spatial data analysis on both vector and raster data. Sen’s slope estimator and the Mann–Kendall (M–K) test are used to investigate the trends in annual and seasonal rainfall throughout all districts and climatic zones of Sri Lanka. The most important thing reflected in this study is that there has been a significant increase in annual rainfall from 1989 to 2019 in all climatic zones (wet, dry, intermediate, and Semi-arid) of Sri Lanka. The maximum increase is recorded in the wet zone and the minimum increase is in the semi-arid zone. There could be an increased risk of floods in the southern and western provinces in the future, whereas areas in the eastern and southeastern districts may face severe droughts during the northeastern monsoon. It is advisable to introduce effective drought and flood management and preparedness measures to reduce the respective hazard risk levels. Full article
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29 pages, 2694 KiB  
Article
Performance and Productivity of Regional Air Transport Systems in China
by Mingli Song and Guangshe Jia
ISPRS Int. J. Geo-Inf. 2021, 10(2), 83; https://doi.org/10.3390/ijgi10020083 - 18 Feb 2021
Viewed by 2552
Abstract
The construction and operation of air transport systems (ATS) needs huge investment, so its performance is of wide concern. The influences of social and economic factors in different regions must be considered when evaluating ATS performance. In this paper, a model combining data [...] Read more.
The construction and operation of air transport systems (ATS) needs huge investment, so its performance is of wide concern. The influences of social and economic factors in different regions must be considered when evaluating ATS performance. In this paper, a model combining data envelopment analysis, stochastic frontier analysis, and bootstrap technique is adopted to evaluate the ‘real’ performance of the air transport system in China. The evaluation results show the ATS performance in different regions. Social and economic factors are proved to pose influences on provincial ATS efficiency. Scale efficiency is the main factor that restricts the efficiency of China’s ATS. Technological change has determined the trend of ATS total factor productivity. The research results may implicate that improvements can be gained by modifying airspace limitations and regulatory conditions that impose significant constraints on ATS. The importance of ATS technological development strategy and the legitimacy of air transport modernization policy are also supported. Full article
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18 pages, 6088 KiB  
Article
Mixed Reality Flood Visualizations: Reflections on Development and Usability of Current Systems
by Ruslan Rydvanskiy and Nick Hedley
ISPRS Int. J. Geo-Inf. 2021, 10(2), 82; https://doi.org/10.3390/ijgi10020082 - 18 Feb 2021
Cited by 20 | Viewed by 3796
Abstract
Interest in and use of 3D visualizations for analysis and communication of flooding risks has been increasing. At the same time, an ecosystem of 3D user interfaces has also been emerging. Together, they offer exciting potential opportunities for flood visualization. In order to [...] Read more.
Interest in and use of 3D visualizations for analysis and communication of flooding risks has been increasing. At the same time, an ecosystem of 3D user interfaces has also been emerging. Together, they offer exciting potential opportunities for flood visualization. In order to understand how we turn potential into real value, we need to develop better understandings of technical workflows, capabilities of the resulting systems, their usability, and implications for practice. Starting with existing geospatial datasets, we develop single user and collaborative visualization prototypes that leverage capabilities of the state-of-the art HoloLens 2 mixed reality system. By using the 3D displays, positional tracking, spatial mapping, and hand- and eye-tracking, we seek to unpack the capabilities of these tools for meaningful spatial data practice. We reflect on the user experience, hardware performance, and usability of these tools and discuss the implications of these technologies for flood risk management, and broader spatial planning practice. Full article
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23 pages, 3317 KiB  
Article
Design and Development of an Internet of Smart Cameras Solution for Complex Event Detection in COVID-19 Risk Behaviour Recognition
by Sepehr Honarparvar, Sara Saeedi, Steve Liang and Jeremy Squires
ISPRS Int. J. Geo-Inf. 2021, 10(2), 81; https://doi.org/10.3390/ijgi10020081 - 18 Feb 2021
Cited by 4 | Viewed by 3708
Abstract
Emerging deep learning (DL) approaches with edge computing have enabled the automation of rich information extraction, such as complex events from camera feeds. Due to the low speed and accuracy of object detection, some objects are missed and not detected. As objects constitute [...] Read more.
Emerging deep learning (DL) approaches with edge computing have enabled the automation of rich information extraction, such as complex events from camera feeds. Due to the low speed and accuracy of object detection, some objects are missed and not detected. As objects constitute simple events, missing objects result in missing simple events, thus the number of detected complex events. As the main objective of this paper, an integrated cloud and edge computing architecture was designed and developed to reduce missing simple events. To achieve this goal, we deployed multiple smart cameras (i.e., cameras which connect to the Internet and are integrated with computerised systems such as the DL unit) in order to detect complex events from multiple views. Having more simple events from multiple cameras can reduce missing simple events and increase the number of detected complex events. To evaluate the accuracy of complex event detection, the F-score of risk behaviour regarding COVID-19 spread events in video streams was used. The experimental results demonstrate that this architecture delivered 1.73 times higher accuracy in event detection than that delivered by an edge-based architecture that uses one camera. The average event detection latency for the integrated cloud and edge architecture was 1.85 times higher than that of only one camera. However, this finding was insignificant with regard to the current case study. Moreover, the accuracy of the architecture for complex event matching with more spatial and temporal relationships showed significant improvement in comparison to the edge computing scenario. Finally, complex event detection accuracy considerably depended on object detection accuracy. Regression-based models, such as you only look once (YOLO), were able to provide better accuracy than region-based models. Full article
(This article belongs to the Collection Spatial Components of COVID-19 Pandemic)
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15 pages, 1775 KiB  
Article
Lost Person Search Area Prediction Based on Regression and Transfer Learning Models
by Ljiljana Šerić, Tomas Pinjušić, Karlo Topić and Tomislav Blažević
ISPRS Int. J. Geo-Inf. 2021, 10(2), 80; https://doi.org/10.3390/ijgi10020080 - 17 Feb 2021
Cited by 7 | Viewed by 3038
Abstract
In this paper, we propose a methodology and algorithms for search and rescue mission planning. These algorithms construct optimal areas for lost person search having in mind the initial point of planning and features of the surrounding area. The algorithms are trained on [...] Read more.
In this paper, we propose a methodology and algorithms for search and rescue mission planning. These algorithms construct optimal areas for lost person search having in mind the initial point of planning and features of the surrounding area. The algorithms are trained on previous search and rescue missions data collected from three stations of the Croatian Mountain Rescue Service. The training was performed in two training phases and having two data sets. The first phase was the construction of a regression model of the speed of walking. This model predicts the speed of walking of a rescuer who is considered a well-trained and motivated person since the model is fitted on a dataset made of GPS tracking data collected from Mountain Rescue Service rescuers. The second phase is the calibration of the model for lost person speed of walking prediction with transfer learning on lost person data. The model is used in the simulation of walking in all directions to predict the maximum area where a person can be located. The performance of the algorithms was analysed with respect to a small dataset of archive data of real search and rescue missions that was available and results are discussed. Full article
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20 pages, 1501 KiB  
Article
Development of Multilayer-Based Map Matching to Enhance Performance in Large Truck Fleet Dispatching
by Ching-Yun Mu, Tien-Yin Chou, Thanh Van Hoang, Pin Kung, Yao-Min Fang, Mei-Hsin Chen and Mei-Ling Yeh
ISPRS Int. J. Geo-Inf. 2021, 10(2), 79; https://doi.org/10.3390/ijgi10020079 - 17 Feb 2021
Cited by 7 | Viewed by 2407
Abstract
Spatial information technology has been widely used for vehicles in general and for fleet management. Many studies have focused on improving vehicle positioning accuracy, although few studies have focused on efficiency improvements for managing large truck fleets in the context of the current [...] Read more.
Spatial information technology has been widely used for vehicles in general and for fleet management. Many studies have focused on improving vehicle positioning accuracy, although few studies have focused on efficiency improvements for managing large truck fleets in the context of the current complex network of roads. Therefore, this paper proposes a multilayer-based map matching algorithm with different spatial data structures to deal rapidly with large amounts of coordinate data. Using the dimension reduction technique, the geodesic coordinates can be transformed into plane coordinates. This study provides multiple layer grouping combinations to deal with complex road networks. We integrated these techniques and employed a puncture method to process the geometric computation with spatial data-mining approaches. We constructed a spatial division index and combined this with the puncture method, which improves the efficiency of the system and can enhance data retrieval efficiency for large truck fleet dispatching. This paper also used a multilayer-based map matching algorithm with raster data structures. Comparing the results revealed that the look-up table method offers the best outcome. The proposed multilayer-based map matching algorithm using the look-up table method is suited to obtaining competitive performance in identifying efficiency improvements for large truck fleet dispatching. Full article
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20 pages, 1138 KiB  
Article
Privacy-Preserving Trajectory Data Publishing by Dynamic Anonymization with Bounded Distortion
by Songyuan Li, Hui Tian, Hong Shen and Yingpeng Sang
ISPRS Int. J. Geo-Inf. 2021, 10(2), 78; https://doi.org/10.3390/ijgi10020078 - 16 Feb 2021
Cited by 5 | Viewed by 2790
Abstract
Publication of trajectory data that contain rich information of vehicles in the dimensions of time and space (location) enables online monitoring and supervision of vehicles in motion and offline traffic analysis for various management tasks. However, it also provides security holes for privacy [...] Read more.
Publication of trajectory data that contain rich information of vehicles in the dimensions of time and space (location) enables online monitoring and supervision of vehicles in motion and offline traffic analysis for various management tasks. However, it also provides security holes for privacy breaches as exposing individual’s privacy information to public may results in attacks threatening individual’s safety. Therefore, increased attention has been made recently on the privacy protection of trajectory data publishing. However, existing methods, such as generalization via anonymization and suppression via randomization, achieve protection by modifying the original trajectory to form a publishable trajectory, which results in significant data distortion and hence a low data utility. In this work, we propose a trajectory privacy-preserving method called dynamic anonymization with bounded distortion. In our method, individual trajectories in the original trajectory set are mixed in a localized manner to form synthetic trajectory data set with a bounded distortion for publishing, which can protect the privacy of location information associated with individuals in the trajectory data set and ensure a guaranteed utility of the published data both individually and collectively. Through experiments conducted on real trajectory data of Guangzhou City Taxi statistics, we evaluate the performance of our proposed method and compare it with the existing mainstream methods in terms of privacy preservation against attacks and trajectory data utilization. The results show that our proposed method achieves better performance on data utilization than the existing methods using globally static anonymization, without trading off the data security against attacks. Full article
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19 pages, 4806 KiB  
Article
Exploring the Influence of E-Hailing Applications on the Taxi Industry—From the Perspective of the Drivers
by Yitong Gan, Hongchao Fan, Wei Jiao and Mengqi Sun
ISPRS Int. J. Geo-Inf. 2021, 10(2), 77; https://doi.org/10.3390/ijgi10020077 - 16 Feb 2021
Cited by 5 | Viewed by 4794
Abstract
In China, the traditional taxi industry is conforming to the trend of the times, with taxi drivers working with e-hailing applications. This reform is of great significance, not only for the taxi industry, but also for the transportation industry, cities, and society as [...] Read more.
In China, the traditional taxi industry is conforming to the trend of the times, with taxi drivers working with e-hailing applications. This reform is of great significance, not only for the taxi industry, but also for the transportation industry, cities, and society as a whole. Our goal was to analyze the changes in driving behavior since taxi drivers joined e-hailing platforms. Therefore, this paper mined taxi trajectory data from Shanghai and compared the data of May 2015 with those of May 2017 to represent the before-app stage and the full-use stage, respectively. By extracting two-trip events (i.e., vacant trip and occupied trip) and two-spot events (i.e., pick-up spot and drop-off spot), taxi driving behavior changes were analyzed temporally, spatially, and efficiently. The results reveal that e-hailing applications mine more long-distance rides and new pick-up locations for drivers. Moreover, driver initiative have increased at night since using e-hailing applications. Furthermore, mobile payment facilities save time that would otherwise be taken sorting out change. Although e-hailing apps can help citizens get taxis faster, from the driver’s perspective, the apps do not reduce their cruising time. In general, e-hailing software reduces the unoccupied ratio of taxis and improves the operating ratio. Ultimately, new driving behaviors can increase the driver’s revenue. This work is meaningful for the formulation of reasonable traffic laws and for urban traffic decision-making. Full article
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16 pages, 3460 KiB  
Article
Impact of Urban Land-Cover Changes on the Spatial-Temporal Land Surface Temperature in a Tropical City of Mexico
by Erika Betzabeth Palafox-Juárez, Jorge Omar López-Martínez, José Luis Hernández-Stefanoni and Héctor Hernández-Nuñez
ISPRS Int. J. Geo-Inf. 2021, 10(2), 76; https://doi.org/10.3390/ijgi10020076 - 13 Feb 2021
Cited by 31 | Viewed by 5323
Abstract
Climate change has severe consequences on ecosystem processes, as well as on people’s quality of life. It has been suggested that the loss of vegetation cover increases the land surface temperature (LST) due to modifications in biogeochemical patterns, generating a phenomenon known as [...] Read more.
Climate change has severe consequences on ecosystem processes, as well as on people’s quality of life. It has been suggested that the loss of vegetation cover increases the land surface temperature (LST) due to modifications in biogeochemical patterns, generating a phenomenon known as “urban heat island” (UHI). The aim of this work was to analyze the effects of urban land-cover changes on the spatiotemporal variation of surface temperature in the tropical city of Mérida, Mexico. To find these effects we used both detected land-cover changes as well as variations of the Normalized Difference Vegetation Index (NDVI). Mérida is ranked worldwide as one of the best cities to live due to its quality of life. Data from satellite images of Landsat were analyzed to calculate land use change (LUC), LST, and NDVI. LST increased ca. 4 °C in the dry season and 3 °C in the wet season because of the LUC. In addition, a positive relationship between the LST and the NDVI was observed mainly in the dry season. The results confirm an increase in the LST as a consequence of the loss of vegetation cover, which favors the urban heat island phenomenon. Full article
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