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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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22 pages, 3954 KiB  
Article
Analysis of Tourism Hotspot Behaviour Based on Geolocated Travel Blog Data: The Case of Qyer
by Michael Kaufmann, Patrick Siegfried, Lukas Huck and Jürg Stettler
ISPRS Int. J. Geo-Inf. 2019, 8(11), 493; https://doi.org/10.3390/ijgi8110493 - 1 Nov 2019
Cited by 15 | Viewed by 6292
Abstract
We contribute a system design and a generalized formal methodology to segment tourists based on their geolocated blogging behaviour according to their interests in identified tourist hotspots. Thus, it is possible to identify and target groups that are possibly interested in alternative destinations [...] Read more.
We contribute a system design and a generalized formal methodology to segment tourists based on their geolocated blogging behaviour according to their interests in identified tourist hotspots. Thus, it is possible to identify and target groups that are possibly interested in alternative destinations to relieve overtourism. A pilot application in a case study of Chinese travel in Switzerland by analysing Qyer travel blog data demonstrates the potential of our method. Accordingly, we contribute four conclusions supported by empirical data. First, our method can enable discovery of plausible geographical distributions of tourist hotspots, which validates the plausibility of the data and its collection. Second, our method discovered statistically significant stochastic dependencies that meaningfully differentiate the observed user base, which demonstrates its value for segmentation. Furthermore, the case study contributes two practical insights for tourism management. Third, Chinese independent travellers, which are the main target group of Qyer, are mainly interested in the discovered travel hotspots, similar to tourists on packaged tours, but also show interest in alternative places. Fourth, the proposed user segmentation revealed two clusters based on users’ social media activity level. For tourism research, users within the second cluster are of interest, which are defined by two segmentation attributes: they blogged about more than just one location, and they have followers. These tourists are significantly more likely to be interested in alternative destinations out of the hotspot axis. Knowing this can help define a target group for marketing activities to promote alternative destinations. Full article
(This article belongs to the Special Issue Convergence of GIS and Social Media)
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18 pages, 3007 KiB  
Article
Strengths of Exaggerated Tsunami-Originated Placenames: Disaster Subculture in Sanriku Coast, Japan
by Yuzuru Isoda, Akio Muranaka, Go Tanibata, Kazumasa Hanaoka, Junzo Ohmura and Akihiro Tsukamoto
ISPRS Int. J. Geo-Inf. 2019, 8(10), 429; https://doi.org/10.3390/ijgi8100429 - 24 Sep 2019
Cited by 4 | Viewed by 3846
Abstract
Disaster-originated placename is a kind of disaster subculture that is used for a practical purpose of identifying a location while reminding the past disaster experience. They are expected to transmit the risks and knowledge of high-risk low-frequency natural hazards, surviving over time and [...] Read more.
Disaster-originated placename is a kind of disaster subculture that is used for a practical purpose of identifying a location while reminding the past disaster experience. They are expected to transmit the risks and knowledge of high-risk low-frequency natural hazards, surviving over time and generations. This paper compares the perceptions to tsunami-originated placenames in local communities having realistic and exaggerated origins in Sanriku Coast, Japan. The reality of tsunami-originated placenames is first assessed by comparing the tsunami run-ups indicated in the origins and that of the tsunami in the Great East Japan Earthquake 2011 using GIS and digital elevation model. Considerable proportions of placenames had exaggerated origins, but the group interviews to local communities revealed that origins indicating unrealistic tsunami run-ups were more believed than that of the more realistic ones. We discuss that accurate hazard information will be discredited if it contradicts to the people’s everyday life and the desire for safety, and even imprecise and ambiguous information can survive if it is embedded to a system of local knowledge that consistently explains the various facts in a local area that requires explanation. Full article
(This article belongs to the Special Issue Historical GIS and Digital Humanities)
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19 pages, 24765 KiB  
Article
Transparent Collision Visualization of Point Clouds Acquired by Laser Scanning
by Weite Li, Kenya Shigeta, Kyoko Hasegawa, Liang Li, Keiji Yano, Motoaki Adachi and Satoshi Tanaka
ISPRS Int. J. Geo-Inf. 2019, 8(9), 425; https://doi.org/10.3390/ijgi8090425 - 19 Sep 2019
Cited by 2 | Viewed by 3271
Abstract
In this paper, we propose a method to visualize large-scale colliding point clouds by highlighting their collision areas, and apply the method to visualization of collision simulation. Our method uses our recent work that achieved precise three-dimensional see-through imaging, i.e., transparent visualization, of [...] Read more.
In this paper, we propose a method to visualize large-scale colliding point clouds by highlighting their collision areas, and apply the method to visualization of collision simulation. Our method uses our recent work that achieved precise three-dimensional see-through imaging, i.e., transparent visualization, of large-scale point clouds that were acquired via laser scanning of three-dimensional objects. We apply the proposed collision visualization method to two applications: (1) The revival of the festival float procession of the Gion Festival, Kyoto city, Japan. The city government plans to revive the original procession route, which is narrow and not used at present. For the revival, it is important to know whether the festival floats would collide with houses, billboards, electric wires, or other objects along the original route. (2) Plant simulations based on laser-scanned datasets of existing and new facilities. The advantageous features of our method are the following: (1) A transparent visualization with a correct depth feel that is helpful to robustly determine the collision areas; (2) the ability to visualize high collision risk areas and real collision areas; and (3) the ability to highlight target visualized areas by increasing the corresponding point densities. Full article
(This article belongs to the Special Issue Historical GIS and Digital Humanities)
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25 pages, 3103 KiB  
Article
Social Media Use in American Counties: Geography and Determinants
by James Pick, Avijit Sarkar and Jessica Rosales
ISPRS Int. J. Geo-Inf. 2019, 8(9), 424; https://doi.org/10.3390/ijgi8090424 - 19 Sep 2019
Cited by 14 | Viewed by 7487
Abstract
This paper analyzes the spatial distribution and socioeconomic determinants of social media utilization in 3109 counties of the United States. A theory of determinants was modified from the spatially aware technology utilization model (SATUM). Socioeconomic factors including demography, economy, education, innovation, and social [...] Read more.
This paper analyzes the spatial distribution and socioeconomic determinants of social media utilization in 3109 counties of the United States. A theory of determinants was modified from the spatially aware technology utilization model (SATUM). Socioeconomic factors including demography, economy, education, innovation, and social capital were posited to influence social media utilization dependent variables. Spatial analysis was conducted including exploratory analysis of geographic distribution and confirmatory screening for spatial randomness. The determinants were identified through ordinary least squares (OLS) regression analysis. Findings for the nation indicate that the major determinants are demographic factors, service occupations, ethnicities, and urban location. Furthermore, analysis was conducted for the U.S. metropolitan, micropolitan, and rural subsamples. We found that Twitter users were more heavily concentrated in southern California and had a strong presence in the Mississippi region, while Facebook users were highly concentrated in Colorado, Utah, and adjacent Rocky Mountain States. Social media usage was lowest in the Great Plains, lower Midwest, and South with the exceptions of Florida and major southern cities such as Atlanta. Measurements of the overall extent of spatial agglomeration were very high. The paper concludes by discussing the policy implications of the study at the county as well as national levels. Full article
(This article belongs to the Special Issue Convergence of GIS and Social Media)
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22 pages, 2973 KiB  
Article
Multi-Scale Remote Sensing Semantic Analysis Based on a Global Perspective
by Wei Cui, Dongyou Zhang, Xin He, Meng Yao, Ziwei Wang, Yuanjie Hao, Jie Li, Weijie Wu, Wenqi Cui and Jiejun Huang
ISPRS Int. J. Geo-Inf. 2019, 8(9), 417; https://doi.org/10.3390/ijgi8090417 - 17 Sep 2019
Cited by 8 | Viewed by 3161
Abstract
Remote sensing image captioning involves remote sensing objects and their spatial relationships. However, it is still difficult to determine the spatial extent of a remote sensing object and the size of a sample patch. If the patch size is too large, it will [...] Read more.
Remote sensing image captioning involves remote sensing objects and their spatial relationships. However, it is still difficult to determine the spatial extent of a remote sensing object and the size of a sample patch. If the patch size is too large, it will include too many remote sensing objects and their complex spatial relationships. This will increase the computational burden of the image captioning network and reduce its precision. If the patch size is too small, it often fails to provide enough environmental and contextual information, which makes the remote sensing object difficult to describe. To address this problem, we propose a multi-scale semantic long short-term memory network (MS-LSTM). The remote sensing images are paired into image patches with different spatial scales. First, the large-scale patches have larger sizes. We use a Visual Geometry Group (VGG) network to extract the features from the large-scale patches and input them into the improved MS-LSTM network as the semantic information, which provides a larger receptive field and more contextual semantic information for small-scale image caption so as to play the role of global perspective, thereby enabling the accurate identification of small-scale samples with the same features. Second, a small-scale patch is used to highlight remote sensing objects and simplify their spatial relations. In addition, the multi-receptive field provides perspectives from local to global. The experimental results demonstrated that compared with the original long short-term memory network (LSTM), the MS-LSTM’s Bilingual Evaluation Understudy (BLEU) has been increased by 5.6% to 0.859, thereby reflecting that the MS-LSTM has a more comprehensive receptive field, which provides more abundant semantic information and enhances the remote sensing image captions. Full article
(This article belongs to the Special Issue Deep Learning and Computer Vision for GeoInformation Sciences)
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30 pages, 25281 KiB  
Article
Japanese Lexical Variation Explained by Spatial Contact Patterns
by Péter Jeszenszky, Yoshinobu Hikosaka, Satoshi Imamura and Keiji Yano
ISPRS Int. J. Geo-Inf. 2019, 8(9), 400; https://doi.org/10.3390/ijgi8090400 - 6 Sep 2019
Cited by 10 | Viewed by 7256
Abstract
In this paper, we analyse spatial variation in the Japanese dialectal lexicon by assembling a set of methodologies using theories in variationist linguistics and GIScience, and tools used in historical GIS. Based on historical dialect atlas data, we calculate a linguistic distance matrix [...] Read more.
In this paper, we analyse spatial variation in the Japanese dialectal lexicon by assembling a set of methodologies using theories in variationist linguistics and GIScience, and tools used in historical GIS. Based on historical dialect atlas data, we calculate a linguistic distance matrix across survey localities. The linguistic variation expressed through this distance is contrasted with several measurements, based on spatial distance, utilised to estimate language contact potential across Japan, historically and at present. Further, administrative boundaries are tested for their separation effect. Measuring aggregate associations within linguistic variation can contrast previous notions of dialect area formation by detecting continua. Depending on local geographies in spatial subsets, great circle distance, travel distance and travel times explain a similar proportion of the variance in linguistic distance despite the limitations of the latter two. While they explain the majority, two further measurements estimating contact have lower explanatory power: least cost paths, modelling contact before the industrial revolution, based on DEM and sea navigation, and a linguistic influence index based on settlement hierarchy. Historical domain boundaries and present day prefecture boundaries are found to have a statistically significant effect on dialectal variation. However, the interplay of boundaries and distance is yet to be identified. We claim that a similar methodology can address spatial variation in other digital humanities, given a similar spatial and attribute granularity. Full article
(This article belongs to the Special Issue Historical GIS and Digital Humanities)
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13 pages, 5944 KiB  
Article
An Examination of the Distribution of White-Collar Worker Residences in Tokyo and Osaka during the Modernizing Period
by Takashi Kirimura
ISPRS Int. J. Geo-Inf. 2019, 8(9), 375; https://doi.org/10.3390/ijgi8090375 - 28 Aug 2019
Cited by 2 | Viewed by 4129
Abstract
This paper sheds light on the residences of white-collar workers in Tokyo and Osaka, Japan in the modernizing period using historical statistical data and telephone directories from a historical geographic information system (GIS) analysis. We examined the differences between the distribution of white-collar [...] Read more.
This paper sheds light on the residences of white-collar workers in Tokyo and Osaka, Japan in the modernizing period using historical statistical data and telephone directories from a historical geographic information system (GIS) analysis. We examined the differences between the distribution of white-collar workers and the progress of suburbanization by comparing the respective unemployment censuses and telephone directories of Tokyo and Osaka. The analysis shows that in 1925, there was a tendency for many white-collar workers to live in certain city sectors, as well as in the city center. However, this trend had changed by the mid-1930s, when data show that private-sector white-collar workers tended to live more in areas with a relatively low population density. Compared to Osaka, Tokyo was relatively suburbanized with white-collar workers in private companies. Full article
(This article belongs to the Special Issue Historical GIS and Digital Humanities)
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17 pages, 2292 KiB  
Article
Expressing History through a Geo-Spatial Ontology
by Humphrey Southall and Paula Aucott
ISPRS Int. J. Geo-Inf. 2019, 8(8), 362; https://doi.org/10.3390/ijgi8080362 - 20 Aug 2019
Cited by 3 | Viewed by 5040
Abstract
Conventional Geographical Information Systems (GIS) software struggles to represent uncertain and contested historical knowledge. An ontology, meaning a semantic structure defining named entities, and explicit and typed relationships, can be constructed in the absence of locational data, and spatial objects can be attached [...] Read more.
Conventional Geographical Information Systems (GIS) software struggles to represent uncertain and contested historical knowledge. An ontology, meaning a semantic structure defining named entities, and explicit and typed relationships, can be constructed in the absence of locational data, and spatial objects can be attached to this structure if and when they become available. We describe the overall architecture of the Great Britain Historical GIS, and the PastPlace Administrative Unit Ontology that forms its core. Then, we show how particular historical geographies can be represented within this architecture through two case studies, both emphasizing entity definition and especially the application of a multi-level typology, in which each “unit” has an unchanging “type” but also a time-variant “status”. The first includes the linked systems of Poor Law unions and registration districts in 19th century England and Wales, in which most but not all unions and districts were coterminous. The second case study includes the international system of nation-states, in which most units do not appear from nothing, but rather gain or lose independence. We show that a relatively simple data model is able to represent much historical complexity. Full article
(This article belongs to the Special Issue Historical GIS and Digital Humanities)
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18 pages, 7754 KiB  
Article
The Suitability of UAS for Mass Movement Monitoring Caused by Torrential Rainfall—A Study on the Talus Cones in the Alpine Terrain in High Tatras, Slovakia
by Rudolf Urban, Martin Štroner, Peter Blistan, Ľudovít Kovanič, Matej Patera, Stanislav Jacko, Igor Ďuriška, Miroslav Kelemen and Stanislav Szabo
ISPRS Int. J. Geo-Inf. 2019, 8(8), 317; https://doi.org/10.3390/ijgi8080317 - 24 Jul 2019
Cited by 45 | Viewed by 4335
Abstract
The prediction of landslides and other events associated with slope movement is a very serious issue in many national parks around the world. This article deals with the territory of the Malá Studená Dolina (Little Cold Valley, High Tatras National Park—Slovakia), where there [...] Read more.
The prediction of landslides and other events associated with slope movement is a very serious issue in many national parks around the world. This article deals with the territory of the Malá Studená Dolina (Little Cold Valley, High Tatras National Park—Slovakia), where there are extensive talus cones, through which seasonally heavy hiking trails lead. In the last few years particularly, there have been frequent falls and landslides in the mountainous environment, which also caused several fatal injuries in 2018. For the above reasons, efforts are being made to develop a methodology for monitoring the changes of the talus cones in this specific alpine area, to determine the size, speed, and character of the morphological changes of the soil. Non-contact methods of mass data collection (laser scanning with Leica P40 and aerial photogrammetry with unmanned aerial system (UAS) DJI Phantom 4 Pro) have been used. The results of these measurements were compared and the overall suitability of both methods for measurement in such terrain evaluated. The standard deviation of the difference of surface determination (represented by the point cloud) is about 0.03 m. As such accuracy is sufficient for the purpose of monitoring talus cones and the use of UAS is easier and associated with lower risk of damage of expensive equipment, we conclude that this method is more suitable for mapping and for repeated monitoring of such terrain. The properties of the outputs of the individual measurement methods, the degree of measurement difficulty and specific measurement conditions in the mountainous terrain, as well as the economy of the individual methods, are discussed in detail. Full article
(This article belongs to the Special Issue Applications of Photogrammetry for Environmental Research)
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18 pages, 5705 KiB  
Article
VS30 Seismic Microzoning Based on a Geomorphology Map: Experimental Case Study of Chiang Mai, Chiang Rai, and Lamphun, Thailand
by Patcharavadee Thamarux, Masashi Matsuoka, Nakhorn Poovarodom and Junko Iwahashi
ISPRS Int. J. Geo-Inf. 2019, 8(7), 309; https://doi.org/10.3390/ijgi8070309 - 18 Jul 2019
Cited by 5 | Viewed by 4314
Abstract
Thailand is not known to be an earthquake-prone country; however, in 2014, an unexpected moderate earthquake caused severe damage to infrastructure and resulted in public panic. This event caught public attention and raised awareness of national seismic disaster management. However, the expertise and [...] Read more.
Thailand is not known to be an earthquake-prone country; however, in 2014, an unexpected moderate earthquake caused severe damage to infrastructure and resulted in public panic. This event caught public attention and raised awareness of national seismic disaster management. However, the expertise and primary data required for implementation of seismic disaster management are insufficient, including data on soil character which are used in amplification analyses for further ground motion prediction evaluations. Therefore, in this study, soil characterization was performed to understand the seismic responses of soil rigidity. The final output is presented in a seismic microzoning map. A geomorphology map was selected as the base map for the analysis. The geomorphology units were assigned with a time-averaged shear wave velocity of 30 m (VS30), which was collected by the spatial autocorrelation (SPAC) method of microtremor array measurements. The VS30 values were obtained from the phase velocity of the Rayleigh wave corresponding to a 40 m wavelength (C(40)). From the point feature, the VS30 values were transformed into polygonal features based on the geomorphological characteristics. Additionally, the automated geomorphology classification was explored in this study. Then, the seismic microzones were compared with the locations of major damage from the 2014 records for validation. The results from this study include geomorphological classification and seismic microzoning. The results suggest that the geomorphology units obtained from a pixel-based classification can be recommended for use in seismic microzoning. For seismic microzoning, the results show mainly stiff soil and soft rocks in the study area, and these geomorphological units have relatively high amplifications. The results of this study provide a valuable base map for further disaster management analyses. Full article
(This article belongs to the Special Issue Geomatics and Geo-Information in Earthquake Studies)
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24 pages, 4108 KiB  
Review
Application of Remote Sensing to the Investigation of Rock Slopes: Experience Gained and Lessons Learned
by Doug Stead, Davide Donati, Andrea Wolter and Matthieu Sturzenegger
ISPRS Int. J. Geo-Inf. 2019, 8(7), 296; https://doi.org/10.3390/ijgi8070296 - 27 Jun 2019
Cited by 33 | Viewed by 6963
Abstract
The stability and deformation behavior of high rock slopes depends on many factors, including geological structures, lithology, geomorphic processes, stress distribution, and groundwater regime. A comprehensive mapping program is, therefore, required to investigate and assess the stability of high rock slopes. However, slope [...] Read more.
The stability and deformation behavior of high rock slopes depends on many factors, including geological structures, lithology, geomorphic processes, stress distribution, and groundwater regime. A comprehensive mapping program is, therefore, required to investigate and assess the stability of high rock slopes. However, slope steepness, rockfalls and ongoing instability, difficult terrain, and other safety concerns may prevent the collection of data by means of traditional field techniques. Therefore, remote sensing methods are often critical to perform an effective investigation. In this paper, we describe the application of field and remote sensing approaches for the characterization of rock slopes at various scale and distances. Based on over 15 years of the experience gained by the Engineering Geology and Resource Geotechnics Research Group at Simon Fraser University (Vancouver, Canada), we provide a summary of the potential applications, advantages, and limitations of varied remote sensing techniques for comprehensive characterization of rock slopes. We illustrate how remote sensing methods have been critical in performing rock slope investigations. However, we observe that traditional field methods still remain indispensable to collect important intact rock and discontinuity condition data. Full article
(This article belongs to the Special Issue Applications of Photogrammetry for Environmental Research)
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21 pages, 11365 KiB  
Article
A New Agent-Based Methodology for the Seismic Vulnerability Assessment of Urban Areas
by Annalisa Greco, Alessandro Pluchino, Luca Barbarossa, Giovanni Barreca, Ivo Caliò, Francesco Martinico and Andrea Rapisarda
ISPRS Int. J. Geo-Inf. 2019, 8(6), 274; https://doi.org/10.3390/ijgi8060274 - 12 Jun 2019
Cited by 7 | Viewed by 3856
Abstract
In order to estimate the seismic vulnerability of a densely populated urban area, it would in principle be necessary to evaluate the dynamic behaviour of individual and aggregate buildings. These detailed seismic analyses, however, are extremely cost-intensive and require great processing time and [...] Read more.
In order to estimate the seismic vulnerability of a densely populated urban area, it would in principle be necessary to evaluate the dynamic behaviour of individual and aggregate buildings. These detailed seismic analyses, however, are extremely cost-intensive and require great processing time and expertise judgment. The aim of the present study is to propose a new methodology able to combine information and tools coming from different scientific fields in order to reproduce the effects of a seismic input in urban areas with known geological features and to estimate the entity of the damages caused on existing buildings. In particular, we present a new software called ABES (Agent-Based Earthquake Simulator), based on a Self-Organized Criticality framework, which allows to evaluate the effects of a sequence of seismic events on a certain large urban area during a given interval of time. The integration of Geographic Information System (GIS) data sets, concerning both geological and urban information about the territory of Avola (Italy), allows performing a parametric study of these effects on a real context as a case study. The proposed new approach could be very useful in estimating the seismic vulnerability and defining planning strategies for seismic risk reduction in large urban areas Full article
(This article belongs to the Special Issue Geomatics and Geo-Information in Earthquake Studies)
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15 pages, 3539 KiB  
Article
Speed Estimation of Multiple Moving Objects from a Moving UAV Platform
by Debojit Biswas, Hongbo Su, Chengyi Wang and Aleksandar Stevanovic
ISPRS Int. J. Geo-Inf. 2019, 8(6), 259; https://doi.org/10.3390/ijgi8060259 - 31 May 2019
Cited by 30 | Viewed by 4506
Abstract
Speed detection of a moving object using an optical camera has always been an important subject to study in computer vision. This is one of the key components to address in many application areas, such as transportation systems, military and naval applications, and [...] Read more.
Speed detection of a moving object using an optical camera has always been an important subject to study in computer vision. This is one of the key components to address in many application areas, such as transportation systems, military and naval applications, and robotics. In this study, we implemented a speed detection system for multiple moving objects on the ground from a moving platform in the air. A detect-and-track approach is used for primary tracking of the objects. Faster R-CNN (region-based convolutional neural network) is applied to detect the objects, and a discriminative correlation filter with CSRT (channel and spatial reliability tracking) is used for tracking. Feature-based image alignment (FBIA) is done for each frame to get the proper object location. In addition, SSIM (structural similarity index measurement) is performed to check how similar the current frame is with respect to the object detection frame. This measurement is necessary because the platform is moving, and new objects may be captured in a new frame. We achieved a speed accuracy of 96.80% with our framework with respect to the real speed of the objects. Full article
(This article belongs to the Special Issue Deep Learning and Computer Vision for GeoInformation Sciences)
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21 pages, 4646 KiB  
Article
A Twitter Data Credibility Framework—Hurricane Harvey as a Use Case
by Jingchao Yang, Manzhu Yu, Han Qin, Mingyue Lu and Chaowei Yang
ISPRS Int. J. Geo-Inf. 2019, 8(3), 111; https://doi.org/10.3390/ijgi8030111 - 28 Feb 2019
Cited by 42 | Viewed by 6991
Abstract
Social media data have been used to improve geographic situation awareness in the past decade. Although they have free and openly availability advantages, only a small proportion is related to situation awareness, and reliability or trustworthiness is a challenge. A credibility framework is [...] Read more.
Social media data have been used to improve geographic situation awareness in the past decade. Although they have free and openly availability advantages, only a small proportion is related to situation awareness, and reliability or trustworthiness is a challenge. A credibility framework is proposed for Twitter data in the context of disaster situation awareness. The framework is derived from crowdsourcing, which states that errors propagated in volunteered information decrease as the number of contributors increases. In the proposed framework, credibility is hierarchically assessed on two tweet levels. The framework was tested using Hurricane Harvey Twitter data, in which situation awareness related tweets were extracted using a set of predefined keywords including power, shelter, damage, casualty, and flood. For each tweet, text messages and associated URLs were integrated to enhance the information completeness. Events were identified by aggregating tweets based on their topics and spatiotemporal characteristics. Credibility for events was calculated and analyzed against the spatial, temporal, and social impacting scales. This framework has the potential to calculate the evolving credibility in real time, providing users insight on the most important and trustworthy events. Full article
(This article belongs to the Special Issue Convergence of GIS and Social Media)
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12 pages, 3523 KiB  
Article
Mapping Canopy Heights of Poplar Plantations in Plain Areas Using ZY3-02 Stereo and Multispectral Data
by Mingbo Liu, Chunxiang Cao, Wei Chen and Xuejun Wang
ISPRS Int. J. Geo-Inf. 2019, 8(3), 106; https://doi.org/10.3390/ijgi8030106 - 27 Feb 2019
Cited by 7 | Viewed by 3142
Abstract
Forest canopy height plays an important role in forest management and ecosystem modeling. There are a variety of techniques employed to map forest height using remote sensing data but it is still necessary to explore the use of new data and methods. In [...] Read more.
Forest canopy height plays an important role in forest management and ecosystem modeling. There are a variety of techniques employed to map forest height using remote sensing data but it is still necessary to explore the use of new data and methods. In this study, we demonstrate an approach for mapping canopy heights of poplar plantations in plain areas through a combination of stereo and multispectral data from China’s latest civilian stereo mapping satellite ZY3-02. First, a digital surface model (DSM) was extracted using photogrammetry methods. Then, canopy samples and ground samples were selected through manual interpretation. Canopy height samples were obtained by calculating the DSM elevation differences between the canopy samples and ground samples. A regression model was used to correlate the reflectance of a ZY3-02 multispectral image with the canopy height samples, in which the red band and green band reflectance were selected as predictors. Finally, the model was extrapolated to the entire study area and a wall-to-wall forest canopy height map was obtained. The validation of the predicted canopy height map reported a coefficient of determination (R2) of 0.72 and a root mean square error (RMSE) of 1.58 m. This study demonstrates the capacity of ZY3-02 data for mapping the canopy height of pure plantations in plain areas. Full article
(This article belongs to the Special Issue Applications of Photogrammetry for Environmental Research)
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16 pages, 8412 KiB  
Article
Consideration of Level of Confidence within Multi-Approach Satellite-Derived Bathymetry
by René Chénier, Ryan Ahola, Mesha Sagram, Marc-André Faucher and Yask Shelat
ISPRS Int. J. Geo-Inf. 2019, 8(1), 48; https://doi.org/10.3390/ijgi8010048 - 19 Jan 2019
Cited by 13 | Viewed by 4270
Abstract
The Canadian Hydrographic Service (CHS) publishes nautical charts covering all Canadian waters. Through projects with the Canadian Space Agency, CHS has been investigating remote sensing techniques to support hydrographic applications. One challenge CHS has encountered relates to quantifying its confidence in remote sensing [...] Read more.
The Canadian Hydrographic Service (CHS) publishes nautical charts covering all Canadian waters. Through projects with the Canadian Space Agency, CHS has been investigating remote sensing techniques to support hydrographic applications. One challenge CHS has encountered relates to quantifying its confidence in remote sensing products. This is particularly challenging with Satellite-Derived Bathymetry (SDB) where minimal in situ data may be present for validation. This paper proposes a level of confidence approach where a minimum number of SDB techniques are required to agree within a defined level to allow SDB estimates to be retained. The approach was applied to a Canadian Arctic site, incorporating four techniques: empirical, classification and photogrammetric (automatic and manual). Based on International Hydrographic Organization (IHO) guidelines, each individual approach provided results meeting the CATegory of Zones Of Confidence (CATZOC) level C requirement. By applying the level of confidence approach, where technique combinations agreed within 1 m (e.g., all agree, three agree, two agree) large portions of the extracted bathymetry could now meet the CATZOC A2/B requirement. Areas where at least three approaches agreed have an accuracy of 1.2 m and represent 81% of the total surface. The proposed technique not only increases overall accuracy but also removes some of the uncertainty associated with SDB, particularly for locations where in situ validation data is not available. This approach could provide an option for hydrographic offices to increase their confidence in SDB, potentially allowing for increased SDB use within hydrographic products. Full article
(This article belongs to the Special Issue Geo-Spatial Analysis in Hydrology)
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