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This exploratory study aimed to evaluate the preferences, expectations, and sense of safety of blind or visually impaired persons regarding three types of pedestrian phasing with audible pedestrian signals configurations that exist in Quebec City (Canada). These include: 1) exclusive phasing with non-directional audible pedestrian signals; 2) exclusive phasing with directional audible pedestrian signals; and 3) concurrent phasing with directional audible pedestrian signals. Thirty-two blind or visually impaired persons were asked to complete a survey. Their preferences and expectations regarding audible pedestrian signals were documented through a series of simulations. Their sense of safety regarding the three existing configurations were also documented. Subsequently, semi-directed, individual interviews with 11 of the individuals who had completed the survey were conducted to build off the collected information. No formal consensus regarding many of the issues discussed were established as participants’ responses varied too significantly. However, findings suggest that the exclusive phasing with directional audible pedestrian signals configuration is perceived to be the safest option by the participants. This study may have practical implications on the design of intersections (e.g., selection of a type of pedestrian phasing with audible pedestrian signal) and the training of blind or visually impaired pedestrians.IMPLICATIONS FOR REHABILITATIONThe addition of audible pedestrian signals to pedestrian signals heightens the sense of safety of blind or visually impaired persons.This study may have practical implications on the design of intersections with audible pedestrian signals and the selection of a type of audible pedestrian signals based on intersection characteristics.Since many participants reported a lower sense of safety when faced with concurrent phasing, it is recommended that more intensive orientation and mobility interventions be provided to blind or visually impaired pedestrians who use this type of traffic signals.Educating road users about blind or visually impaired pedestrians appears also essential. The addition of audible pedestrian signals to pedestrian signals heightens the sense of safety of blind or visually impaired persons. This study may have practical implications on the design of intersections with audible pedestrian signals and the selection of a type of audible pedestrian signals based on intersection characteristics. Since many participants reported a lower sense of safety when faced with concurrent phasing, it is recommended that more intensive orientation and mobility interventions be provided to blind or visually impaired pedestrians who use this type of traffic signals. Educating road users about blind or visually impaired pedestrians appears also essential.

OpenStreetMap (OSM) is one of the most well-known volunteered geographic information (VGI) projects that aims to produce a free-world map. However, there are serious concerns about its quality. Numerous studies have assessed the quality of OSM by comparing the OSM database with a reference database. Several researchers have proposed the use of quality indicators as variables that can describe OSM quality in regions where no reference data are available. A quality indicator is a variable that has a significant monotonic relationship with quality measures. In this study, a literature review was conducted to identify and define the main quality measures proposed for assessing the quality of linear features. Owing to limited access to current data, only three quality elements—completeness, positional accuracy, and attribute accuracy—were evaluated in this study. These quality measures were then used to assess the quality of the OSM roads in the province of Quebec. Finally, Spearman’s rank correlation coefficient test was applied to determine whether there was a significant correlation between the quality measures related to the three quality elements and the five potential quality indicators: population, average income, density of OSM roads, density of OSM buildings, and number of points of interest (POI). The main contribution of this study is testing the following hypothesis: “There is a significant correlation between the five mentioned variables and the measures related to the three quality elements”. Statistical analysis showed that in terms of completeness, the density of OSM roads and population were the best indicators; in terms of positional accuracy, population and income were the best indicators; and in terms of attribute accuracy, completeness was the best indicator. All five variables have significant correlations with the measures of the three elements of quality, except for the following two pairs (attribute accuracy, density of OSM roads) and (attribute accuracy, density of OSM buildings). This study proposes the density of OSM roads and number of POI as two new quality indicators that have not been found in the literature review.

Indoor localization and mapping are essential for a wide range of applications. The absence of GPS signals in indoor environments such as buildings, caves, and tunnels brings significant challenges for applications where accurate positioning (i.e., centimeter-level accuracy) is required. This paper presents a scoping review of the most recent studies on precise indoor localization and mapping using mobile technologies, specifically, mobile laser scanners. The scoping review allows for a comprehensive and structured review of the literature to maximize the capture of relevant information and provide reproducible results. We extracted and reported a range of information from the selected articles published since 2009, with the goal of identifying the most frequently used sensors and methods of fusing their collected observations. The results show that in the majority of studies, LiDAR is the core sensor and IMUs with 75% and odometers with 67% magnitude are the main sensors integrated with the LiDAR system to enhance the localization precision. In addition, the classical iterative closest point (ICP) algorithm with approximately 60% frequency and the extended Kalman filter (EKF) method with over 40% frequency are the main algorithms used for the scan matching and fusion of different sensor data, respectively. This scoping review also revealed the lack of mapping-systems calibration as the main limitation in over 70% of the papers analyzed.

Knowledge of route accessibility is indispensable for "wheeled mobility device" users to travel safely and efficiently; however, current navigation technologies hardly provide adapted information for this population. Aims of the study were to collect data on the usability of a navigation application and to propose a version 1.0 of the Evaluation of satisfaction with geospatial assistive technology (ESGAT), by addressing the criterion, construct and cross-cultural validities.A filmed field trial and a methodological study were conducted in parallel. Thirty wheeled mobility device users were filmed planning and making a 10-minute known journey using the HERE WeGo app. The ESGAT, ÉSTGA (French version) and theFourteen men and 16 women averaging 45.9 years old tried out HERE WeGo; 14 were powered wheelchair users. Usability of the app was moderate (good effectiveness, moderate efficiency and quite satisfied). The criterion validity of the ÉSTGA was good (ESGAT and ÉSTGA 1.0 questionnaires are now available in English and French with a total mean score (11 items), an informatics subscore (mean of 5 items) and a geomatic subscore (mean of 6 items). Their validation should be pursued with new navigation applications. IMPLICATIONS FOR REHABILITATIONClinicians should ask their clients using a wheeled mobility device to test navigation applications to ensure their safety and complete the

BACKGROUND Although there have been recent efforts to improve access to Canadian national parks, many remain not fully accessible to people with disabilities. Winter conditions, in particular, present challenges that limit their participation in outdoor activities. OBJECTIVE To develop a novel method to assess park access during winter that will inform recommendations for national park standards to meet needs of all park visitors (regardless of ability) during winter conditions. METHODS A larger participatory mixed-methods research project exploring park access was adapted [1]. Specifically, the second phase of the study to conduct in-person winter mobile interviews (i.e., walking and wheeling interviews) with people who have a wide range of disabilities while visiting three parks in two provinces was modified. Changes were made to accommodate the extreme winter weather conditions in Quebec while using safe and informative data collection methods. In Quebec, one park, where winter conditions are safer, will be assessed in person (n=4). Virtual interviews will be used to facilitate the assessment of other winter and summer conditions in two other parks (n=8). RESULTS - CONCLUSIONS We expect that adapting the protocol to gather further information on winter conditions and access to parks will provide high-quality and rich data to better inform park access standards. This participatory mixed-methods research will inform the development of park standards that consider the accessibility needs of all people.

Manual wheelchair users are more vulnerable, in situations such as road crossings, hazardous sidewalks or curbs and crossing of buildings and facilities threshold. Geospatial assistive technology (GAT) can help with route planning. However, it is important to ensure the usability of such products, as well as the satisfaction of persons with reduced mobility. The study's aim was (1) to develop and validate a questionnaire on the satisfaction of GAT, in English and French, and to (2) assess satisfaction, efficacy and efficiency of a GAT with manual wheelchair users following a filmed trial in a dense urban area.A methodological study was conducted (development of the questionnaire, assessment of its content validity, feasibility and practicability) followed by a trial and post-observations with the videos. Two questionnaires (English, French) were concurrently validated by two groups of experts (The Evaluation of satisfaction with geospatial assistive technology (ESGAT) consists in a user profile and their experience with the technology, followed by 12 satisfaction criteria rated from 1-not satisfied to 5-very satisfied. Both questionnaires were rated as feasible and practicable to complete. The usability of Google Maps Pedestrian routeing tool was measured as "moderate" by manual wheelchairs since the total satisfaction score at the ESGAT was 3.9/5 (quite satisfied). The items with the lowest score were navigation assistance, hands-free function and security. The GAT was effective (87.5% have completed their destination) but not efficient (37.5% needed help).IMPLICATIONS FOR REHABILITATIONFor manual wheelchair users paired with geospatial assistive technology:• A 10 minutes questionnaire was developed and validated to assess their satisfaction after testing aid in an urban area.• Satisfaction criteria to address are ease of access (service), learnability, hands-free function, ease of use for planning as well for navigating, transportability/ appearance, content, geographic information, effectiveness, efficiency, navigation assistance and security• A field test is necessary to ensure the effectiveness of the technology in avoiding or announcing potential obstacles such as sidewalk crossing ramp, damaged and congested sidewalk; sidewalk tilt (side slopes); thresholds at destination; verbal indication too soon or too late; incorrect indication; the arrow does not indicate the right direction; readjustment of the route needed; a lack of indication; and human intervention needed.

BACKGROUND Canada’s national parks are world-renowned. However, despite recent attempts to improve access, many are not accessible to people with disabilities. With the advent of provincial and federal legislation, standards are being developed to assist with the design and management of parks. OBJECTIVE The overarching objective of this study is to inform accessibility standards for federal parks that meet the needs of all park visitors, regardless of ability. The specific objectives of this study are to identify park accessibility standards that exist internationally, identify the accessibility challenges that people with disabilities face in park environments, and prioritize and recommend accessibility standards for national parks. METHODS A 3-phase approach will be used to achieve the study objectives. In the first phase, a scoping review of the existing accessibility standards will be conducted. The second phase will include objective audits of trails and features in 6 parks, 3 in western Canada and 3 in eastern Canada, as well as mobile interviews with 24 diverse participants in each region regarding their experiences of and recommendations for improving the park’s accessibility. In the final phase, a Delphi participatory consensus development process will be used, based on the data gathered in the first 2 phases, to prioritize recommendations for standards. RESULTS We expect to find gaps in existing standards that do not account for the diverse range of accessibility requirements that people with disabilities have for visiting parks. We also expect to find that existing standards, on their own, may not be enough to ensure equitable access to all the experiences and amenities that parks have to offer. Development of subsequent guidelines and best practices may be necessary to address complex scenarios for which standards may not be the best approach to ensuring accessibility. CONCLUSIONS The participatory and mixed methods approaches used in this study will provide rich insights for developing accessible park standards that consider the diverse needs of people with disabilities. The findings will also support the development or enhancement of park standards at all levels of government. INTERNATIONAL REGISTERED REPORT DERR1-10.2196/33611

Background Canada’s national parks are world-renowned. However, despite recent attempts to improve access, many are not accessible to people with disabilities. With the advent of provincial and federal legislation, standards are being developed to assist with the design and management of parks. Objective The overarching objective of this study is to inform accessibility standards for federal parks that meet the needs of all park visitors, regardless of ability. The specific objectives of this study are to identify park accessibility standards that exist internationally, identify the accessibility challenges that people with disabilities face in park environments, and prioritize and recommend accessibility standards for national parks. Methods A 3-phase approach will be used to achieve the study objectives. In the first phase, a scoping review of the existing accessibility standards will be conducted. The second phase will include objective audits of trails and features in 6 parks, 3 in western Canada and 3 in eastern Canada, as well as mobile interviews with 24 diverse participants in each region regarding their experiences of and recommendations for improving the park’s accessibility. In the final phase, a Delphi participatory consensus development process will be used, based on the data gathered in the first 2 phases, to prioritize recommendations for standards. Results We expect to find gaps in existing standards that do not account for the diverse range of accessibility requirements that people with disabilities have for visiting parks. We also expect to find that existing standards, on their own, may not be enough to ensure equitable access to all the experiences and amenities that parks have to offer. Development of subsequent guidelines and best practices may be necessary to address complex scenarios for which standards may not be the best approach to ensuring accessibility. Conclusions The participatory and mixed methods approaches used in this study will provide rich insights for developing accessible park standards that consider the diverse needs of people with disabilities. The findings will also support the development or enhancement of park standards at all levels of government. International Registered Report Identifier (IRRID) DERR1-10.2196/33611

Rapid and timely evaluation and monitoring of the urban environment has gained significant importance in understanding the state of urban sustainability in metropolises. Multi-source remote sensing (RS) data are a valuable source for a comprehensive understanding of urban environmental changes in developing countries. However, in the Middle East, a region with several developing countries, limited study has been conducted to understand urban environmental changes. In this study, to evaluate the changes in the urban environment, 32 metropolises in the Middle East were studied between 2000 and 2019. For this purpose, a comprehensive environmental index (CEI) integrated with Google Earth Engine (GEE) platform for processing and analysis is introduced. The results show degraded environmental conditions in 19 metropolises based on a significant increasing trend in the time series of the CEI index. The highest increasing trend in the value of the CEI was observed in the cities of Makkah, Jeddah, Basra, Riyadh, and Sana’a. The results also show that the percentage of urban areas in all 32 cities that falls into the degraded class varies from 5% to 75% between 2005 and 2018. The results of CEI changes in megacities, such as Ajman, Tehran, Jeddah, Makkah, Riyadh, Karaj, and Sana’a show that these cities have increasingly suffered from the degradation of environmental conditions since 2001. According to the results, it is recommended to pay more attention to environmental issues regarding the future of urban development in these cities. The proposed approach in this study can be implemented for environmental assessment in other regions.

Background Although there have been recent efforts to improve access to Canadian national parks, many remain not fully accessible to people with disabilities. Winter conditions, in particular, present challenges that limit their participation in outdoor activities. Objective This study aimed to develop a novel method to assess park access during winter, which will inform recommendations for national park standards to meet the needs of all park visitors (regardless of ability) during winter conditions. Methods A larger participatory mixed methods research project exploring park access was adapted. A 3-phase approach has already been proposed to achieve the study objectives. In the first phase, a scoping review of the existing accessibility standards will be conducted. In the second phase, objective audits of trails and features in 6 parks, 3 in western Canada and 3 in eastern Canada, will be conducted, as well as mobile interviews with 24 various participants in each region regarding their experiences of and recommendations for improving the park’s accessibility. In the final phase, a Delphi participatory consensus development process will be used, based on the data gathered in the first 2 phases, to prioritize recommendations for standards. This paper will focus on the second phase of the study, specifically on whether the in-person winter mobile interviews (ie, walking and wheeling interviews) with people who have a wide range of disabilities while visiting 3 parks in 2 provinces were modified. Changes were made to accommodate the extreme winter weather conditions in Quebec while using safe and informative data collection methods. Results In Quebec, one park, where winter conditions are safer, has been assessed in person (n=4). Web-based interviews were used to facilitate the assessment of other winter and summer conditions in two other parks (n=8). Winter and web-based interviews were completed in April 2022. Data are currently being collected and analyzed, and results will be completed by December 2022. Conclusions We expect that adapting the protocol to gather further information on winter conditions and access to parks will provide high-quality and rich data to better inform park access standards. This participatory mixed methods research will inform the development of park standards that consider the accessibility needs of all people. International Registered Report Identifier (IRRID) DERR1-10.2196/38715

Optimal sensor network deployment in built environments for tracking, surveillance, and monitoring of dynamic phenomena is one of the most challenging issues in sensor network design and applications (e.g., people movement). Most of the current methods for sensor network deployment and optimization are empirical and they often result in important coverage gaps in the monitored areas. To overcome these limitations, several optimization methods have been proposed in the recent years. However, most of these methods oversimplify the environment and do not consider the complexity of 3D architectural nature of the built environments specially for indoor applications (e.g., indoor navigation, evacuation, etc.). In this paper, we propose a novel local optimization algorithm based on a 3D Voronoi diagram, which allows a clear definition of the proximity relations between sensors in 3D indoor environments. This proposed structure is integrated with an IndoorGML model to efficiently manage indoor environment components and their relations as well as the sensors in the network. To evaluate the proposed method, we compared our results with the Genetic Algorithm (GA) and the Covariance Matrix Adaptation Evolution Strategy (CMA-ES) algorithms. The results show that the proposed method achieved 98.86% coverage which is comparable to GA and CMA-ES algorithms, while also being about six times more efficient.

Purpose: To advance knowledge of specific usability criteria for Geospatial Assistive Technologies (GATs) and manual wheelchair users, and to develop a profile and expectations for potential future...

Biomethanation projects across the world struggle with multiple challenges related to the location selection and optimization of the treatment facilities. Important aspects such as treatment plant location and treatment process chain configuration depend on the waste sources to be treated, the required end-product type and quality, as well as its final use destination, all of which are variable in time and space. This research describes the development and use of an integrated decision-support software tool that allows setting up optimal organic waste value chains, named optim-O. Key features of the tool include a multidimensional spatiotemporal database, a model-based decision module for simulation and optimization, as well as a user-friendly interface. The availability of such a software tool will not only allow to save time and money on data collection and calculations, but will also induce more comprehensive decisions by simultaneously taking into account a variety of factors, thereby significantly facilitating and enhancing the decision-making process.

Background: Social participation is beneficial for individuals’ health. However, people with disabilities that may lead to mobility limitations tend to experience lower levels of social participation. Information and communication technologies such as the OnRoule mobile application (app) can help promote social participation. Objectives: To obtain potential users’ perceptions on the usability and content of the OnRoule app for providing information on accessibility, as well as its potential to optimize social participation. Materials and Methods: Cross-sectional user-centered design study. Individuals with physical disabilities (n = 18) were recruited through community organizations and interviewed using a semi-structured guide. Interviews were recorded, transcribed, and analyzed using thematic analysis. Results: Three main themes were identified: (1) “user-friendliness”, (2) “balance between the amount and relevance of information”, and (3) “potential use of the app”. Discussion and Conclusion: Findings from this study indicated that the app was easy to use, had pertinent information, and enabled a positive experience of finding information. However, several areas of improvement were identified, such as the clarity of specific elements, organization and amount of information, optimization of features, and inclusiveness. Apps such as OnRoule could optimize social participation by facilitating the process of finding resources in the community and building a sense of connectedness between users.

Urban public spaces, especially in big cities, are the spaces most prone to criminal activities. Parks are among the most important public spaces designed for walking, sport, and other rec...

Our contemporary understanding of disability is rooted in the idea that disability is the product of human-environment interaction processes. People may be functionally limited, but this becomes a disability only when they engage with their immediate social and physical environments. Any attempt to address issues of mobility in relation to people with disabilities should be grounded in an ontology that encompasses this understanding.The objective of this study is to provide a methodology to integrate the social and physical environments in the development of a mobility ontology for people with motor disabilities (PWMD).We propose to create subclasses of concepts based on a Nature-Development distinction rather than creating separate social and physical subclasses. This allows the relationships between social and physical elements to be modelled in a more compact and efficient way by specifying them locally within each entity, and better accommodates the complexities of the human-environment interaction as well. Based on this approach, an ontology for mobility of PWMD considering four main elements - the social and physical environmental factors, human factors, life habits related to mobility and possible goals of mobility - is presented.We demonstrate that employing the Nature-Development perspective facilitates the process of developing useful ontologies, especially for defining the relationships between the social and physical parts of the environment. This is a fundamental issue for modelling the interaction between humans and their social and physical environments for a broad range of applications, including the development of geospatial assistive technologies for navigation of PWMD. Implications for rehabilitation The proposed perspective may actually have much broader interests beyond the issue of disability - much of the interesting dynamics in city development arises from the interaction between human-developed components - the built environment and its associated entities - and natural or organic components. The proposed approach facilitates the process of developing useful ontologies, especially for defining the relationships between the social and physical parts of the environment. This is a fundamental issue for modeling the interaction between human -specially people with disabilities -and his social and physical environments in a broad range of domains and applications, such as Geographic Information Systems and the development of geospatial assistive technologies for navigation of people with disabilities, respectively.

Background: Wheelchair users are increasingly using route planners and navigation systems to help them get around the city. The absence of a list of usability criteria for wheelchair user-centred design and recommending geospatial assistive technologies creates uncertainty about the choices to be made by rehabilitation clinicians and geographic information systems specialists. The aim of this study was to compile such a list by identifying usability criteria from standardized questionnaires linked to user interfaces and geospatial assistive technologies (GATs).Material and methods: We conducted a scoping review in ACM Digital Library, Inspec/Compendex and PsycINFO for the period 2005-2016 using keyword strategies. From 84 articles identified, after screening and exclusion procedures, 15 articles were selected. Data were extracted from them and reported in table 1 (relevant questionnaires listed in alphabetical order, type of user interface, population studied, psychometric properties, type of measurement scale and information about the construct, number of subscales and items) and in table 2 (usability criteria up to 20 items for the questionnaires, scales or constructs, pointing criteria as gold standard in physical rehabilitation and as in geographic information).Results: We identified 87 usability criteria in 12 standardized questionnaires in 15 articles (with at least two types of psychometric properties). There are 54 usability criteria that could be used in clinical situations concerning their potential applicability to GATs for wheelchair users: 20 are familiar to rehabilitation clinicians who recommend assistive technologies, 21 are generic to GATs while 13 are specific to mobile applications or voice recognition systems. It remains 34 criteria that are not actually familiar to clinicians: actual use, content (including content-clarity, content-color, content-consistency, content-credibility, content-legibility, content-relevance, content-trustworthy, and content-understandable), control-obviousness, customer service behavior, delivery format, design-application, ease of navigation, entry-point type, everyday words, fingertip-size controls, font, functions-expected, functions-integration, gestalt, graphics, habit, hierarchy, input, network externality, speech characteristics, structure, subtle animation, time spent waiting, transition, user goal orientation and verbosity.Conclusions: More research is needed to develop a questionnaire specific to geospatial assistive technologies for wheelchair users linked with mobile applications and information content.Implications for rehabilitationFor manual wheelchair users paired with geospatial assistance technology, "effectiveness, efficiency, learnability and satisfaction" are essential criteria for route planning and navigation task.Clinicians can optimize the selection of a geospatial assistance technology considering 16 criteria: appearance, assistance-human support, comfort, ease of holding, ease of use, emotional aspect, endurance, facilitating conditions, intention to use, minimal memory load, physical effort, price value, simplicity, social influence, training and usefulness.Clinicians should have in mind that WC users want to plan a route with as few obstacles as possible. Information on the screen should be accessible to WC users (text, contrast, symbols, graphics, photos, voice, vibration, route views). Hands are occupied with the hand rims, WC users would prefer "listen to verbal" instructions to continue their route instead of looking on their electronic device. 34 criteria are specific for route planning and navigation task.

In this paper, we propose a decentralized semantic reasoning approach for modeling vague spatial objects from sensor network data describing vague shape phenomena, such as forest fire, air pollution, traffic noise, etc. This is a challenging problem as it necessitates appropriate aggregation of sensor data and their update with respect to the evolution of the state of the phenomena to be represented. Sensor data are generally poorly provided in terms of semantic information. Hence, the proposed approach starts with building a knowledge base integrating sensor and domain ontologies and then uses fuzzy rules to extract three-valued spatial qualitative information expressing the relative position of each sensor with respect to the monitored phenomenon’s extent. The observed phenomena are modeled using a fuzzy-crisp type spatial object made of a kernel and a conjecture part, which is a more realistic spatial representation for such vague shape environmental phenomena. The second step of our approach uses decentralized computing techniques to infer boundary detection and vertices for the kernel and conjecture parts of spatial objects using fuzzy IF-THEN rules. Finally, we present a case study for urban noise pollution monitoring by a sensor network, which is implemented in Netlogo to illustrate the validity of the proposed approach.

Social dimension of environment is an important aspect that should be reflected in research works related to studying the interactions between human and the environment. However, this dimension is usually neglected when representing the environment in geographic information systems for different applications. For instance, disability as a result of the interaction between human and environment is influenced by social and physical dimensions of environment. Although, this aspect is highlighted in most conceptual disability models by defining various taxonomies of the environment, from ontological perspective justifying and connecting social dimension to the physical dimension of the environment is not clearly determined. Integrating social dimension of the environment with its physical dimension for disability studies is a challenging task, which is the main objective of the present study. Here, we review some of the disability models and their perspective about classifying the environment. Then, from ontological perspective, their limitations are discussed and a new approach for the classification of concepts form the environment is presented. This approach facilitates and simplifies integration of social dimension in ontologies for more effective assessment of disability issue in Geographic Information System.

In a traditional Geographical Information System (GIS), one usually characterizes spatial entities by their individual placename (or toponym) and a set of defined attributes. These entities and their attributes are structured in table frames with functional relations, plus coordinates of their geometric primitives for location in a quantified space. In such a case, one considers the geographical names of these entities as unique identifiers under the standardized ‘generic-specific’ binomial, in one-to-one relationships with features of interest on the ground. This technical perspective convenes quite well to administrators of land-based public mandates needing univocal references to particular places for planning as well as daily applications (e.g., municipal, postal, emergency). But, from a linguistic point of view, the exact location and dimensions of places are among other attributes of the toponym itself, since the study of placenames looks mainly to its meaning, etymology, and evolution in particular language(s) through the epochs of naming practices, forming kind of toponymic “strata”. So, that is investigatory, documented, critical, often anecdotal, sometimes even searching for identity, but devotes few considerations to the geographical place per se, its landscape nor its limits. On the other hand, the geographical perspective to placenames comes more concerned by a real or identifiable place within its vicinity and the dynamics of situations occurring in that location at multiple scales in the same period, whatever the names covering part or all the area. Thus, looking for a place based information system to structure perceived or unofficial places of specified interest require the design and development of tools and functionalities able to support analysis of such information for particular purposes (personal, commercial, military, transit, indigenous, participatory, tourism, etc.). In such a context, definition of their substantial components requires other technical means than their descriptive attributes and geometric primitives. Over the rational spatial databases as a base map, the user of a platial information system would design place-entities on an autonomous fashion, more subjective and colloquial, while referring to landmarks for identity or distinction with respect to different people, being inhabitant, local worker or just visitor. The place-entity comes to the mind like a shapeless mass with a core and some peripheries, where it shows an oriented front or façade, or a force line as a trend, and more fuzzy and moveable limits on the other sides. For instance, downtown and the central business district may not correspond to each other as platial synonyms. For this purpose, the necessary data structures remain to be developed. To do so, Voronoi tessellation, with its flexible spatial proximity definition and its topological (instead of geometrical) properties, represents an interesting alternative model for further researches. For short, a Voronoi diagram partitions the space into regions such that any location is associated with its nearest Voronoi generators (centroids representing places). This allows an adaptive discretization of the space, and provides a simple and intuitive basis for the definition of adjacency relations between the generation points. Depending on the distribution of generating points, Voronoi cells can approximate place extensions close to human perception of those places with flexibility and still keep the fundamental qualitative relations between places, thanks to topological properties of this model. Irregularity of such Voronoi model also has a significant advantage that allow to better approximate places and their variable distribution in the geographical space. Here in this paper, we also consider scale as an important factor for the representation and analysis of the places approximated with Voronoi cells. Indeed, in higher level, a place may be constituted either by the aggregation of several places in fine scales or by their parts. Hierarchical Voronoi diagram can also be considered to model such relations between places and their vertical relations, for instance where a same particular placename identifies different features or entities that overlap, evolve, or have various limits or meanings. In such a model, moving between different scales or data “levels” is done without being worried about exact aggregation of lower geometries in a high-level place representation. In order to structure Voronoi hierarchies for a set of points representing centroids of places, one must start by constructing Voronoi cells for the finest level and then creating pointers that relate higher level places to the lower ones. Based on its unique properties, Voronoi tessellation, among strong solutions for platial information systems, can provide a firm base for representing the complexity of places, either as entities (or features) and toponyms that identify or refer to them. Paralleling relational GIS data frames, it would allow to adapt to unusual or fuzzy places, to represent their geographical evolution, to preserve their name and spatial extension, and to take good notes of local or ancient variants and even of exonyms applied to such places from abroad. Thus, it presents an opportunity to map the sense, if not the spirit, of place.

Evacuation planning is an important activity in disaster management. Due to the sudden occurrence of disasters, evacuation should be preplanned. It is necessary for evacuation plan to be as close as possible to a real evacuation operation. However, evacuation planning is challenging because of inherent uncertainty in required information. One important source of uncertainty in evacuation is the uncertainty in evacuation demands. This paper presents an evacuation vehicle routing problem to design evacuation routes for public vehicles. In this problem, demand (number of evacuees) at each pick-up point is introduced as a fuzzy number and the assignment of the pick-up points to the vehicle routes happens based on a credibility preference index. A genetic algorithm based on fuzzy credibility theory is designed to optimize the problem. The optimum parameter set for genetic algorithm is obtained by Taguchi experimental design. The presented problem and algorithm are applied on a part of Tehran transportation network. The impact of credibility preference index on the achieved solutions is evaluated and its best value is determined for the case study. Moreover, different tests are implemented to analyze and discuss the influence of uncertainty level on the final results.

An obvious way to assist people with disabilities in their efforts to move around in urban areas is to offer information regarding accessible path segments that take into account their specific needs. Providing safe navigation in urban areas for people with disabilities can substantially enhance their opportunities for full social participation and the exercise of their basic rights. In order to offer these people information on accessible paths, we need to assess the accessibility of pedestrian networks . Accessibility is the result of interactions between the individual and the environment. These interactions need to be more carefully considered when we evaluate accessibility for persons with disabilities. This paper proposes a new approach for assessing accessibility, based on user confidence while moving around in urban space. For validation purposes, the proposed approach is applied in the Saint-Roch area of Quebec City using confidence information from 127 manual wheelchair users. The results are presented and discussed and further research perspectives are proposed.

Sensor deployment optimization to achieve the maximum spatial coverage is one of the main issues in Wireless geoSensor Networks (WSN). The model of the environment is an imperative parameter that influences the accuracy of geosensor coverage. In most of recent studies, the environment has been modeled by Digital Surface Model (DSM). However, the advances in technology to collect 3D vector data at different levels, especially in urban models can enhance the quality of geosensor deployment in order to achieve more accurate coverage estimations. This paper proposes an approach to calculate the geosensor coverage in 3D vector environments. The approach is applied on some case studies and compared with DSM based methods.

Given the volumetric nature of the ocean, 3D spatial modeling and interpolation could be a key to a better understanding of continuous abiotic and biotic phenomena that compose the marine ecosystem, although such techniques are rarely used and their actual performance is poorly studied. Here, we evaluate the performance of 3D spatial interpolation for five pelagic variables derived from a typical oceanographic campaign conducted in the southeastern Beaufort Sea (Canadian Arctic) in 2009. Our main objective is to evaluate and compare the performance of a deterministic interpolation method (inverse distance, IDW) and a geostatistical method (ordinary kriging, OK) with a variation of method input parameters (search neighborhood, weights) for variables with increasing complexity in terms of data anisotropy and sampling configuration. Performance of different 3D interpolation strategies is evaluated by cross-validation and a qualitative comparison of 3D spatial models. Our results show that OK was the optimal ...

One of the main challenges in Coastal Erosion Risk Assessment (CERA) is integrating and analysis of conflicting data in various time periods and spatial scales through dissimilar environmental, social, and economic criteria. Currently, Geographical Information Systems (GIS) are widely used in risk assessment despite their drawbacks and limitations as transactional systems for multi-scales, multi-epochs, and multi-themes analysis. Hence, an analytical conceptual framework is proposed in this paper based on geospatial business intelligence paradigm to develop a Spatial Multidimensional Conceptual Model (SMCM) to assess coastal erosion risk. The model is designed based on Spatial On-Line Analytical Processing (SOLAP) platform, on the top of both analytical and transactional paradigms, to allow fast synthesis of cross-tabulated data and easy comparisons over space, scales, epochs, and themes. This objective is achieved through a comprehensive integration of multiple environmental, social, and economic criteria as well as their interactions at various scales. It also takes into account multiple elements at risk such as people, infrastructure, and built environment as different dimensions of analysis. Using this solution allows decision makers to benefit from on-demand, interactive, and comprehensive information in a way that is not possible using GIS alone. The developed model can easily be adapted for any other coastal region through the proposed framework to perform risk assessment. The advantages and drawbacks of the proposed framework are also discussed and new research perspectives are presented.

This paper proposes a probabilistic sensor model for the optimization of sensor placement. Traditional schemes rely on simple sensor behaviour and environmental factors. The consequences of these oversimplifications are unrealistic simulation of sensor performance and, thus, suboptimal sensor placement. In this paper, we develop a novel probabilistic sensing model for sensors with line-of-sight-based coverage (e.g., cameras) to tackle the sensor placement problem for these sensors. The probabilistic sensing model consists of membership functions for sensing range and sensing angle, which takes into consideration sensing capacity probability as well as critical environmental factors such as terrain topography. We then implement several optimization schemes for sensor placement optimization, including simulated annealing, limited-memory Broyden-Fletcher-Goldfarb-Shanno method, and covariance matrix adaptation evolution strategy.

A precise estimation and the characterization of the spatial variability of microclimate conditions (MCCs) are essential for risk assessment and site-specific management of vector-borne diseases and crop pests. The objective of this study was to estimate at local scale, and assess the uncertainties of Surface Microclimate Indicators (SMIs) derived from airborne infrared thermography and multispectral imaging. SMIs including Surface Temperature (ST) were estimated in southern Quebec, Canada. The formulation of their uncertainties was based on in-situ observations and the law of propagation of uncertainty. SMIs showed strong local variability and intra-plot variability of MCCs in the study area. The ST values ranged from 290 K to 331 K. They varied more than 17 K on vegetable crop fields. The correlation between ST and in-situ observations was very high (r = 0.99, p = 0.010). The uncertainty and the bias of ST compared to in-situ observations were 0.73 K and ±1.42 K respectively. This study demonstrated that very high spatial resolution multispectral imaging and infrared thermography present a good potential for the characterization of the MCCs that govern the abundance and the behavior of disease vectors and crop pests in a given area. (Resume d'auteur)

GIScience 2016 Short Paper Proceedings An Object Based Approach for Submarine Canyon Identification from Surface Networks Andres Cortes Murcia 1,2 , Eric Guilbert 1,2 , Mir Abolfazl Mostafavi 1,2 Dept. of Geomatics Sciences, Universite Laval, Quebec, G1V 0A6 (QC) Canada Center for research in geomatics, Universite Laval, Quebec, G1V 0A6 (QC) Canada Email: andres.cortes-murcia.1@ulaval.ca {eric.guilbert; mir-abolfazl.mostafavi}@scg.ulaval.ca Abstract In this paper we propose using surface networks to identify submarine canyons from bathymetric data. Identification is done in two steps. First, thalweg lines that fit the canyon definition are extracted; second, the floor around each thalweg is measured to separate steep narrow canyons from broader channels. Results are validated against a classification provided by geomorphologists. 1. Introduction Submarine canyons are relevant features for geomorphologists because they can explain the origin and evolution of marine landscape. Although there is a common understanding of what a canyon is, its description is often vague and its definition is not applicable for automatic classification. This issue leads to define parameters with arbitrary values that are difficult to establish. Traditional methods require image segmentation and classification. These approaches compute discrete local descriptors such as the curvature and depend on threshold parameters chosen by the user. Furtermore, image classification can omit global photo-interpretative characteristics. In general, photo-interpreters identify canyons by their overall shape (narrow, elongated, steep slopes) and position (running across the continental slope in a straight line), observed around salient thalwegs. This paper proposes an approach where thalwegs are extracted from a terrain surface network and canyons are built around them. We move away from pixel classification to an object-oriented approach built on a topological structure. The surface network is a graph where critical points such as pits and peaks are connected by ridges and thalwegs. Its extraction does not require any parameter. Relevant thalwegs are selected by simplifying the surface network. Simplification parameters are not set locally at pixel level but at the structure level. The valley floor is computed around each thalweg and used to classify canyons and other channels. The method is illustrated on a triangulated irregular network generated from multibeam sounding data from the St-Lawrence estuary (Canada). Results were validated against a manual classification performed by geomorphologists (Normandeau et a.l 2015). 2. Surface Network Construction A surface network is a topological graph. Its nodes are pits (local minima), peaks (local maxima) and saddles (points being a local maximum in one direction and a local minimum in another direction). Saddles are connected to peaks by ridges and to pits by thalwegs (Figure 1). The integrity of the surface network is guaranteed by several topological constraints.

GIScience 2016 Short Paper Proceedings Modelling Vague Shape Dynamic Phenomena from Sensor Network data using a Decentralized Fuzzy Rule-Based Approach Roger Cesarie Ntankouo Njila 1 , Mir Abolfazl Mostafavi 1 , Jean Brodeur 1 Centre de Recherche en Geomatique, 2314 Pavillon Casault; Universite Laval, Quebec, Canada, G1K 7P4 Email: roger-cesarie.ntankouo-njila.1@ulaval.ca, Mir-Abolfazl.Mostafavi@scg.ulaval.ca, recherchegeosemantic@videotron.ca Abstract Modelling dynamic phenomena of vague shape from sensor data is still a challenging problem for many applications. In this paper, we propose a decentralized fuzzy rule-based approach based on fuzzy object model to build a more realistic spatiotemporal representation for such phenomena. This approach has been successfully implemented in a simulation case of bushfire monitoring, showing advantages for spatial decision making in a disaster management context. Keywords: sensors, sensor data, fuzzy objects, disaster management, spatial decision support 1. Introduction Extracting geospatial information from geosensor data can help to better understand a complex phenomenon for real time decision making process (Sadeq et al. 2013). Several approaches are used for the extraction of geospatial information from sensor data. Many of these approaches are developed based on the assumption that monitored phenomena are of crisp shape with well- defined boundaries. However, many dynamic phenomena have vague spatial boundaries, and their accurate detection and extraction from sensor data is a challenging problem. In this paper we propose a decentralized fuzzy rule-based approach to address this problem. In the proposed method, sensors detect vague shape phenomena using a fuzzy logic reasoning approach and collaborate with their neighboring sensors to infer vague spatial extent of the phenomena and its dynamics. We adopt Crisp-Fuzzy objects (Pauly and Schneider 2008) as a more realistic model for large scale and vague shape dynamic phenomena. This paper is organized as follows. After a brief background presented in section 2, section 3 describes the proposed approach implemented in section 4 for a bushfire simulation case showing it applicability for real time spatial decision process in disaster management. Section 5 presents conclusions and future works. 2. Background Spatial computing can be undertaken in a sensor system following a centralized (all data are sent to process center), a decentralized (located at sensor site or other site) or a hybrid approach (Chong and Kumar 2003). Crisp vector objects are extracted in the existing approaches using statistics or filters (Chintalapudi and Govindan 2003) or qualitative reasoning (Guan and Duckham 2009). Real-world phenomena are inherently uncertain (Carniel et al. 2015). Crisp-Fuzzy objects model (Pauly and Schneider 2008) is an interesting candidate for the representation of such phenomenon. In this model the geometry of object is composed of a kernel and a conjecture part, the kernel part belongs definitely and always to the vague object but one can’t say with certainty whether conjecture part considered as the broad boundary belongs to the vague object.

Large volumes of geospatial data are increasingly made available through dynamic networks, such as ad hoc networks. Consequently, new adapted query propagation approaches that take into account geospatial aspects of data are needed. Different existing query propagation approaches use various criteria to select relevant sources. In addition, many approaches rely on existing semantic mappings between sources; however, in ad hoc networks, sources move autonomously and in a dynamic fashion. Our goal is rather to reduce the number of sources that must be accessed to answer a query and, therefore, to reduce the volume of semantic mappings that needs to be computed to answer the query. In this paper, we propose three real time query propagation strategies to address this issue. Those strategies reproduce the behavior of members of a social network. The strategies are designed to be part of a real time semantic interoperability framework for ad hoc networks of geospatial databases. The strategies have been formalized with the Lightweight Coordination Calculus (LCC), which support distributed interactions based on social norms and constraints. The implementation and testing of the strategies show that they complement each other to provide optimal query answers.

The configuration of mental representation of space plays a major role in successful navigational activities. Therefore, navigational assistance for pedestrians who are blind should help them to better configure their mental representation of the environment. In this paper, we propose and exploit a computational model for the mental representation of urban areas as an aid to orientation and navigation for visually impaired pedestrians. Our model uses image schemata to capture the spatial semantics and configural elements of urban space necessary for this purpose. These image schemata are schematic structures that are continually requested by individuals in their perception, bodily movement and interaction with surrounding objects. Our proposed model also incorporates a hierarchical structure to provide different levels of detail tied to appropriate spatial perspectives at each scale. We presume that such computational model will help us to develop an appropriate structure of spatial data used to assist the target population. At the end of the paper, we illustrate the utility of our configural model by developing a typical scenario for the navigation of a blind pedestrian in an urban area.

Efficient collaboration between participants is fundamental for urban planning and design processes, but it is not necessarily easy to achieve. This limitation depends on several factors including differences in participants' backgrounds and the limitations and the complexity of the tools used to support those process. Furthermore, the collaborative component of urban planning and design projects is often limited to meetings where designs and plans are assembled and discussed. The solution presented in this paper, aims at overcoming those problems through a collaborative geospatial augmented reality application. The proposed system integrates innovative technologies of augmented reality with 3D modelling and spatial analysis tools. Results of our experimentations demonstrate the potential of such a system for improving interactive and collaborative urban design. This paper provides a comparison of our approach with existing ones and proposes future developments in the field. RESUME. Si la bonne collaboration entre participants est fondamentale dans les processus d'amenagement et de design, elle n'est pas toujours facile a mettre en œuvre. Differents facteurs expliquent cette difficulte, allant des differences d'origines des participants, a la complexite des outils utilises par les experts. Par ailleurs, la composante collaborative des projets d'amenagement et de design est souvent limitee aux seules phases d'assemblage et de discussions sur les plans. Precisement, dans cet article nous proposons une solution fondee sur une application de realite augmentee geospatiale collaborative. Le systeme propose associe des technologies de realite augmentee innovantes et des outils de modelisation 3D et d'analyse spatiale. Les resultats de nos tests montrent la pertinence de ce type de systeme pour ameliorer l'interaction et la collaboration en design urbain. Cet article fournit une comparaison entre l'approche developpee et les approches existantes et propose finalement des voies de developpement futures.

Imposing integrity constraints is an efficient way to improve data quality in databases. Effective imposition of integrity constraints requires their precise distinction and specification. Despite a few efforts for enhancing the distinction and specification of the integrity constraints in spatial and spatiotemporal databases by their classifications, these classifications fail to precisely distinguish between inherently dissimilar integrity constraints. Furthermore, the existing classifications provide imprecise definitions for the classes of integrity constraints. Such shortcomings explain why still diverse terms are used to refer to a same spatial integrity constraint. In this paper, we propose a formal and more exhaustive classification of the integrity constraints in spatiotemporal databases relying on their nature with respect to space, time, and themes. Moreover, a terminology for the integrity constraints of spatiotemporal databases is presented. Finally, we discuss the advantages of the proposed classification in the specification of integrity constraints.

Geographic information systems (GISs) are widely used for representation, management, and analysis of spatial data in many disciplines. In particular, geoscientists increasingly use these tools for data integration and management purposes in many environmental applications, ranging from water resources management to the study of global warming. Beyond these capabilities, geoscientists need to model and simulate three-dimensional (3D) dynamic fields and readily integrate those results with other relevant spatial information in order to have a better understanding of the environmental problems. However, GISs are very limited for the modeling and simulation of spatial fields, which are mostly 3D and dynamic. These limitations are mainly related to the existing GIS spatial data structures that are static and limited to 2D space. In order to overcome these limitations, we develop and implement a new kinetic 3D spatial data structure based on Delaunay tetrahedralization and a 3D Voronoi diagram to support a 3D dynamic field simulation within GISs. In this article, we describe in detail the different steps from discretization of a 3D continuous field to its numerical integration, based on an event-driven method. For validation of the proposed spatial data structure itself and its potential for the simulation of a dynamic field, two case studies are presented in the article. According to our observations, during the simulation process, the data structure is maintained and the 3D spatial information is managed adequately. Furthermore, the results obtained from both experiments are very satisfactory and are comparable with the results obtained from other existing methods for the simulation of the same dynamic field. To conclude, we discuss the current challenges related to the development of the 3D kinetic data structure itself and its adaptation to 3D dynamic field simulation and suggest some solutions for its improvement.

LiDAR technology can provide very detailed and highly accurate geospatial information on an urban scene for the creation of Virtual Geographic Environments (VGEs) for different applications. However, automatic 3D modeling and feature recognition from LiDAR point clouds are very complex tasks. This becomes even more complex when the data is incomplete (occlusion problem) or uncertain. In this paper, we propose to build a knowledge base comprising of ontology and semantic rules aiming at automatic feature recognition from point clouds in support of 3D modeling. First, several modules for ontology are defined from different perspectives to describe an urban scene. For instance, the spatial relations module allows the formalized representation of possible topological relations extracted from point clouds. Then, a knowledge base is proposed that contains different concepts, their properties and their relations, together with constraints and semantic rules. Then, instances and their specific relations form an urban scene and are added to the knowledge base as facts. Based on the knowledge and semantic rules, a reasoning process is carried out to extract semantic features of the objects and their components in the urban scene. Finally, several experiments are presented to show the validity of our approach to recognize different semantic features of buildings from LiDAR point clouds.

Semantic similarity is a fundamental notion in GIScience for achieving semantic interoperability among geospatial data. Until now, several semantic similarity models have been proposed; however, few of these models address the issues related to the assessment of semantic similarity in ad hoc networks. Also, several models are based on a definition of concepts where features are independent, an assumption that reduces the richness of the geospatial concept representation. This article presents the conceptual basis for Sim-Net, a novel semantic similarity model for ad hoc networks based on Description Logics (DL). Sim-Net is based on the multi-view paradigm. This paradigm is used to include inferential knowledge in semantic similarity, that is, the knowledge about implicit dependencies between features of concepts. In Sim-Net, assessing semantic similarity relies on the notions of Semantic Reference Systems and Formal Concept Analysis (FCA), which are combined to establish a common semantic reference frame for ontologies of the ad hoc network called the view lattice. The Sim-Net semantic similarity measure distinguishes concepts that belong to different or similar domains and takes into account the neighbours of a concept in the network. An application example is used to show the positive impact of the properties of Sim-Net.

This study proposes an earthquake evacuation routing plan from local shelters to regional ones for a long-term safe settlement using public vehicles. In a post-earthquake situation, the unpredicted changes in travel demand patterns and accessibility conditions of the transportation network affect the travel time. The contribution of this study is to propose a dynamic evacuation routing approach that can update the routing plan by incorporating time-dependent travel times. The problem is modeled as a vehicle routing problem and a two-stage solution procedure based on the simulated annealing algorithm is developed. The model is applied in part of Tehran’s transportation network. The results confirm that the dynamic evacuation routing approach is able to increase the number of evacuated shelters and decrease both the evacuation time and total travel time of the vehicles. The findings in this study indicate that the application of the proposed model can provide beneficial information for disaster mana...

This paper proposes a new Free-Lagrange method based on the kinetic Voronoi diagram for fluid simulation. The objective here is to combine the advantages of an adoptive mesh structure with the advantages of kinetic mesh maintenance, and demonstrate their value for dynamic simulation. Despite the theoretical advantages of the Free-Lagrange method, its use has been handicapped with the reconstruction of topology after each time step that considerably reduces the efficiency of the method. In addition, the use of fixed time steps causes problems such as overshoots and undetected collisions. In order to demonstrate the ability of the proposed model to solve these problems, the method is applied to a dam-breaking problem and global tides. With the results obtained from these numerical experiments, the validity of the global kinetic data structure is approved. In particular, the method is found to be more efficient than existing methods. In addition, qualitative comparison of physical results with analytical sol...

This paper presents simple point insertion and deletion operations in Voronoi diagrams and Delaunay triangulations which may be useful for a wide variety of applications, either where interactivity is important, or where local modification of the topology is preferable to global rebuilding. While incremental point insertion has been known for many years, point deletion is relatively unknown. The robustness and efficiency of a new algorithm are described. A variety of potential applications are summarized, and the included computer program may be used as the basis for many new projects.

Wildfire simulators based on empirical or physical models need to be locally calibrated and validated when used under conditions that differ from those where the simulators were originally developed. This study aims to calibrate FARSITE fire spread model considering a set of recent wildfires occurred in Northern Iran forests. Site specific fuel models in the study areas were selected by sampling the main natural vegetation type complexes and assigning standard fuel models. Overall, simulated fires presented reliable outputs that accurately replicated the observed fire perimeters and behavior. Standard fuel models of Scott and Burgan (2005) afforded better accuracy in the simulated fire perimeters than the standard fuel models of Anderson (1982). The best match between observed and modeled burned areas was observed on herbaceous type fuel models. Fire modeling showed a high potential for estimating spatial variability in fire spread and behavior in the study areas. This work represents a first step in the application of fire spread modeling on Northern Iran for wildfire risk monitoring and management.

Semantic interoperability is needed to support meaningful data exchanges in distributed environments such as ad hoc networks of geospatial databases and geospatial web services. Even with the increasing popularity of ontologies to capture semantics, semantics of geospatial data are often too weak to support meaningful exchanges. In this chapter, the authors argue that semantically weak geospatial data can be enriched to enhance semantic interoperability. They propose a conceptual architecture designed to support enhanced semantic interoperability in dynamic networks that focuses on semantic enrichment. The proposed conceptual architecture includes a coalition management module, an ontology enrichment module, and a semantic mapping module; the modules perform different types of semantic enrichment and can support various semantic interoperability tasks. Within the different enrichment methods, the authors explain the role of global ontologies, arguing that they play a key role in a semantic interoperability framework. Finally, the authors illustrate with an application example the possibilities of such architecture.

This paper outlines the concept of a “global GIS,” and defines various aspects of its development, as well as various options and decisions that must be made. The emphasis is on the advantages and disadvantages of maintaining a global topological structure, and whether topology should be generated “on the fly” in response to a specific query. We first define what we mean by “space” in this context, followed by a description of topological structures and how we may use them in the context of graph traversal problems. We then describe some appropriate data structures. After mentioning some of the real-world problems associated with polygon construction problems, we touch on how graphs may represent change over time. A global topological structure is then proposed which resolves some of the problems mentioned. This is based on incremental graph updating methods. Some unresolved problems associated with using global topological structures are then discussed, especially those associated with queries, such as polygon overlay, that generate a new local topological structure. We conclude with some preliminary rules, and suggest further work.

Large scale disasters often create the need for evacuating affected regions to save lives. Disaster management authorities need evacuation simulation tools to assess the efficiency of various evacuation scenarios and the impact of a variety of environmental and social factors on the evacuation process. Therefore, sound simulation models should include the relevant factors influencing the evacuation process and allow for the representation of different levels of detail, in order to support large scale evacuation simulation while also offering the option of considering factors operating at a finer level of detail, such as at the single individual level. In particular, the impact of social factors, such as interaction between agents, should be integrated into the simulation model to reflect the reality of evacuation processes. In this paper, we present a generic data model for agent-based evacuation simulation that includes the relevant social parameters identified in the emergency literature. The model is composed of three sub-models that describe the agents, their context and behaviour, the dynamic environment in which the agents evolve and the parameters of the evacuation scenario. The objective of this model is to improve the simulation so that it can be better represent reality.

Finding relevant geospatial information is increasingly critical because of the growing volume of geospatial data available through distributed environments. It is also a challenge for the ongoing development of the Geospatial Semantic Web.Data brokers provide searchable repositories through which users can generally retrieve the requested data. But generally, these mechanisms lack the capacity to find and combine complementary data from multiple sources. However, such capacity is needed to answer complex queries. In this paper, we propose a new type of system that supports geospatial data retrieval from multiple and complementary sources. The system uses the Semantic Query-Enhanced Web Rule Language (SQWRL) to support reasoning with complex queries and to enable combination of complementary and heterogeneous data. We have developed and included in this system a query expansion method for the resolution of semantic heterogeneities. The proposed system is illustrated with an application example.

This paper proposes a framework for the optimization of sensor placement. Traditional schemes rely on simple sensor behaviours and environmental factors. The consequences of these oversimplifications are unrealistic simulation of sensor performance and, thus, suboptimal sensor placement. In this paper, we develop a novel framework to tackle the sensor placement problem using a probabilistic coverage and corresponding membership functions for sensing range and sensing angle, which takes into consideration sensing capacity probability as well as critical environmental factors such as terrain topography. We then implement several optimization schemes for sensor placement optimization, including simulated annealing, L-BFGS, and CMA-ES.

Recent advances in sensor technology have resulted in the design and development of more efficient and low cast sensor networks for environmental monitoring, object surveillance, tracking and controlling of moving objects, etc. The deployment of a sensor network in a real environment presents several challenging issues that are often oversimplified in the existing solutions. Different approaches have been proposed in the literatures to solve this problem. Many of these approaches use Voronoi diagram and Delaunay triangulation to identify sensing holes in the network and create an optimal arrangement of the sensors to eliminate the holes. However, most of these methods do not consider the reality of the environment in which the sensor network is deployed. This paper presents a survey of the existing solutions for geosensor network optimization that use Voronoi diagram and Delaunay triangulation and identifies their limitations in a real world application. Next, it proposes a more realistic approach by integrating spatial information in the optimization process based on Voronoi diagram. Finally the results of two cases studies based on the proposed approach in natural area and urban environment are presented and discussed.

Recent advances in sensors technology have led to design and development of variety of geosensor networks and their applications in many disciplines. Such networks consist of a set of sensors laying on different locations and sensing various real world phenomena for environmental monitoring, object surveillance, tracking and controlling applications. A fundamental issue in a geosensor network optimization is estimation of its spatial coverage. The existence of various obstacles in the sensing environment and its complexity result in several holes in the environment. These holes should be detected and minimized in the optimization process. Different approaches have been proposed in the literatures to resolve these problems. A considerable number of current approaches use Voronoi diagram and Delaunay triangulation to identify the holes in the network and deploy an optimal arrangement for the sensors. These structures are more compatible with the spatial distribution of sensors in the environment. This paper presents a survey of the existing solutions for geosensor network optimization that use Voronoi diagram and Delaunay triangulation in their approach.