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1.
Data modelling is a critical stage of database design. Recent research has focused upon object-oriented data models, which appear more appropriate for certain applications than either the traditional relational model or the entity-relationship approach. The object-oriented approach has proved to be especially fruitful in application areas, such as the design of geographical information systems which have a richly structured knowledge domain and are associated with multimedia databases. This article discusses the key concepts in object-oriented modelling and demonstrates the applicability of an object-oriented design methodology to the design of geographical information systems. In order to show more clearly how this methodology may be applied, the paper considers the specific object-oriented data model IFO. Standard cartographic primitives are represented using IFO, which are then used in the modelling of some standard administrative units in the United Kingdom. The paper concludes by discussing current research issues and directions in this area.  相似文献   

2.
Abstract

In state-of-the-art GIS, geographical features are represented as geometric objects with associated topological relations and classification attributes. Semantic relations and intrinsic interrelations of the features themselves are generally neglected. In this paper, a feature-based model that enhances the representation of geographical features is described. Features, as the fundamental depiction of geographical phenomena, encompass both real world entities and digital representation. A feature-based object incorporates both topological relations among geometric elements and non-topological (semantic) relations among features. The development of an object-oriented prototype feature-based GIS that supports relations between feature attributes and feature classes is described. Object-oriented concepts such as class inheritance and polymorphism facilitate the development of feature-based GTS.  相似文献   

3.
ABSTRACT

High performance computing is required for fast geoprocessing of geospatial big data. Using spatial domains to represent computational intensity (CIT) and domain decomposition for parallelism are prominent strategies when designing parallel geoprocessing applications. Traditional domain decomposition is limited in evaluating the computational intensity, which often results in load imbalance and poor parallel performance. From the data science perspective, machine learning from Artificial Intelligence (AI) shows promise for better CIT evaluation. This paper proposes a machine learning approach for predicting computational intensity, followed by an optimized domain decomposition, which divides the spatial domain into balanced subdivisions based on the predicted CIT to achieve better parallel performance. The approach provides a reference framework on how various machine learning methods including feature selection and model training can be used in predicting computational intensity and optimizing parallel geoprocessing against different cases. Some comparative experiments between the approach and traditional methods were performed using the two cases, DEM generation from point clouds and spatial intersection on vector data. The results not only demonstrate the advantage of the approach, but also provide hints on how traditional GIS computation can be improved by the AI machine learning.  相似文献   

4.
Abstract

This paper presents a data model to manage networks with a Geographical Information System with some consideration of the path operator. The data model is based on the merge of graph theory concepts and the object-oriented paradigm. The introduction of the Master_nodes (with respect to Master_edges) allows definition of a node (with respect to an edge) as an abstraction of a sub-network. A network can be defined using several levels of definition (detail) following the importance of the nodes (with respect to the edges) within an application. The object-oriented concepts are applied to both the alphanumerical data part and to the modelling part of the topology of the graph. The data manipulation operators are basic operators. These operators are the union, an intersection and a difference. More elaborated operators, such as under constraints paths, are obtained by combining these basic operators. We present some considerations of the path operator in a GIS context and introduce the concept of the ‘Open Graph Assumption’ and the notion of direction. These notions take full advantage of the data model and represent an alternative way of defining the path operator. This modelling is well adapted to take account of multi-level networks (i.e., the definition of a view in the context of a multi-user configuration or cartographic generalization).  相似文献   

5.
《The Journal of geography》2012,111(5):250-256
Abstract

In this study, pairs of students in fifth and seventh grade generated and answered questions based on maps. More than 90 percent of the questions they generated made sense with reference to the map on which they were based. Each of these questions was coded in terms of both its informational content (symbols, latitude and longitude, and scale) and the process by which a map user obtains the information from the map (map reading, map interpreting, map inferring). Results indicated that students most often generated three types of questions, which together accounted for more than 80 percent of all the questions: 1) read symbol, 2) infer latitude and longitude, and 3) interpret scale. Qualitatively, the questions were analyzed for what they revealed about student confusion about map content. Problems with all three aspects of map content were common among both fifth- and seventh-grade students. The problem-posing technique proved useful for evaluating student's knowledge.  相似文献   

6.
《The Journal of geography》2012,111(3):427-433
Abstract

Research presented in this paper addresses two fundamental questions: how effective have state geographic alliance summer geography institutes (ASGIs) been in changing the classroom teaching behaviors of participants, and to what extent do the institutes reflect characteristics of effective inservice training? Both questions are grounded in Shulman's concept of pedagogical content knowledge—the notion that effective teaching requires knowledge of how specific ideas and procedures in a particular content domain can best be taught. On-site evaluations and four follow-up evaluations provided data regarding the strengths and weaknesses of the institutes as well as evidence regarding the institutes' long-term effectiveness in promoting change in geography instruction. Results of the study indicate that ASGI graduates not only make substantive changes in how they teach geography, but also conduct high-quality inservices that lead to changes in the teaching practices of their colleagues.  相似文献   

7.
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8.
Abstract

The opportunities available at a demand location are usually measured as the costs of reaching a specified critical number of facilities from that location. This method does not however, account for multistop trips nor for differences in the diversity of supply at the level of individual facilities. In this paper we introduce an alternative measurement method that overcomes these shortcomings. In this method the probability of successfully visiting a specific facility is assumed to be a function of the diversity of supply provided. Trip routes are constructed that have an acceptable probability of success. Then, the expected costs of travelling the optimum route are determined as an indicator of spatial opportunities. The proposed method has been implemented in a GIS environment, using typical GIS data and GIS tools for spatial analysis and display. The results of a case study indicate that the new method, compared to current methods, may lead to different evaluations of the level of opportunities at demand locations.  相似文献   

9.
《The Journal of geography》2012,111(5):513-518
Abstract

Preservice teacher education based on content, skills, and perspectives specified in Geography for Life: National Geography Standards 1994 is essential for dissemination of the Standards to classrooms all across the country. Curricular materials are often structured around the five fundamental themes of geography; however, it is essential that teacher preparation courses integrate the content of the Standards into the themes of location, place, human—environment interaction, and region. One model of this approach to preservice education, as summarized here, provides future teachers with a conceptual basis for learning and teaching geography, enhancing opportunities for disseminating solid geography content to all grade levels nationwide.  相似文献   

10.
ABSTRACT

Defining and identifying duplicate records in a dataset is a challenging task which grows more complex when the modeled entities themselves are hard to delineate. In the geospatial domain, it may not be clear where a mountain, stream, or valley ends and begins, a problem carried over when such entities are catalogued in gazetteers. In this paper, we take two gazetteers, GeoNames and SwissNames3D, and perform matching – identifying records in each that are about the same entity – across a sample of natural feature records. We first perform rule-based matching, establishing competitive results, then apply machine learning using Random Forests, a method well-suited to the matching task. We report on the performance of a wider array of matching features than has been previously studied, including domain-specific ones such as feature type, land cover class, and elevation. Our results show an increase in performance using machine learning over rules, with a notable performance gain from considering feature types, but negligible gains from other specialized matching features. We argue that future work in this area should strive to be more reproducible and report results on a realistic testing pipeline including candidate selection, feature extraction, and classification.  相似文献   

11.
ABSTRACT

Spatial information of land values is fundamental for planners and policy makers. Individual appraisals are costly, explaining the need for predictive modelling. Recent work has investigated using Space Syntax to analyse urban access and explain land values. However, the spatial dependence of urban land markets has not been addressed in such studies. Further, the selection of meaningful variables is commonly conducted under non-spatialized modelling conditions. The objective of this paper is to construct a land value map using a geostatistical approach using Space Syntax and a spatialized variable selection. The methodology is applied in Guatemala City. We used an existing dataset of residential land value appraisals and accessibility metrics. Regression-kriging was used to conduct variable selection and derive a model for spatial prediction. The prediction accuracy is compared with a multivariate regression. The results show that a spatialized variable selection yields a more parsimonious model with higher prediction accuracy. New insights were found on how Space Syntax explains land value variability when also modelling the spatial dependence. Space Syntax can contribute with relevant spatialized information for predictive land value modelling purposes. Finally, the spatial modelling framework facilitates the production of spatial information of land values that is relevant for planning practice.  相似文献   

12.
Abstract

Many data structures are possible for the storage of topological information for computer-based maps. The PAN graph is here suggested as an aid in the selection of a strategy appropriate to the application. Examples are given for the mapping of triangular networks and Thiessen polygons. Application of the technique is appropriate to both education in, and design of, spatial data structures for automated cartography and geographical information systems  相似文献   

13.
ABSTRACT

Abstract. Geographers use spatial reasoning extensively in large-scale spaces, i.e., spaces that cannot be seen or understood from a single point of view. Spatial reasoning differentiates several spatial relations, e.g. topological or metric relations, and is typically formalized using a Cartesian coordinate system and vector algebra. This quantitative processing of information is clearly different from the ways human draw conclusions about spatial relations. Formalized qualitative reasoning processes are shown to be a necessary part of Spatial Expert Systems and Geographical Information Systems.

Addressing a subset of the total problem, namely reasoning with cardinal directions, a completely qualitative method, without recourse to analytical procedures, is introduced and a method for its formal comparison with quantitative formula is defined. The focus is on the analysis of cardinal directions and their properties. An algebraic method is used to formalize the meaning of directions. The standard directional symbols (N, W, etc.) are supplemented with a symbol corresponding to an undetermined direction between points too close to each other which greatly increases the power of the inference rules. Two specific systems to determine and reason with cardinal directions are discussed in some detail.

From this example and some other previous work, a comprehensive set of research steps is laid out, following a mathematically based taxonomy. It includes the extension of distance and direction reasoning to extended objects and the definitions of other metric relations that characterize situations when objects are not disjointed. The conclusions compare such an approach with other concepts.  相似文献   

14.
《The Journal of geography》2012,111(3):163-168
Abstract

This paper explores the concept of relevancy in the context of an introductory physical geography course. The concern is with a relevant content and structure. Both are introduced through a problem-orientation. Current societal problems related to the physical environment are used to introduce students to conditions and processes involving environmental elements such as atmosphere, water, soil, vegetation, and topography. Because they are societal problems, the additional element, man, is included. The structure assumes a priori that the student has some prior knowledge of environmental problems. With a relatively high level of individual involvement, the student is asked to utilize this knowledge in learning about environmental processes and physical geographic concepts. Feedback from student to instructors is maximized through greater reliance on discussion groups, exercises, papers, and a problem-solving examination. In transmitting subject matter and environmental problems information, greater reliance is placed on readings and less on lectures.  相似文献   

15.

The utility of nonmetric, multidimensional-scaling techniques is demonstrated for the analysis and collection of environmental-cognition data. By comparing the multidimensional-scaling solutions of a real-setting map to scaling solutions for sketch maps and two psychophysical, distance-scaling procedures, we demonstrate that magnitude estimation of actual interpoint distances is comparable in accuracy to sketch maps when produced without constraints, or when subjects are given a specified list of landmarks to include on their maps. Triadic comparisons of actual interpoint distances were less accurate than the three other techniques.  相似文献   

16.
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17.
Abstract

This paper reports on progress towards the development of a personal guidance system for a blind navigator. The system is being developed in light of the unique problems facing the blind traveller, which are discussed first. The system consists of four modules: a locator unit, a detailed spatial database, an algorithm for path selection and a user interface. Suggestions are offered for alternative ways of handling the locator problem using a global positioning system or a database query system. The nature of the geographic information system (GIS) to be used as a host for the database is discussed, followed by brief statement of the criteria for choosing an algorithm for path selection and suggestions on types of user interfaces best suited to the system. A report on a pilot-study GIS is presented. Special problems of database and system design are highlighted.  相似文献   

18.

This paper examines the need to carry out primary health care administration, programming and planning beyond the established 110 districts in Ghana. The framework for delimiting the sub-districts is offered by the availability of digital data such as the district boundary, site location, road network and population. Using the specified travel distance from predetermined sites, network analysis generates approximate polygons around the health centres to create functional areas ? the health sub-districts. Additional sites are proposed based on a set of criteria which includes proximity, centrality, population and existing level of infrastructural development in an attempt to improve coverage and bring the total utilization of health facilities closer to 100% in the study area.  相似文献   

19.

Although acts of creation, scientific or artistic, result from metaphorical and mythological speculations, the role of metaphor and myth has largely been neglected in attempts to develop a geographical epistemology. The significance of these concepts is illustrated by the use of the frontier symbol as a means of understanding both the social structure of the contemporary black inner city and the temporal dimension of the recent expansion of human activities into nighttime.  相似文献   

20.

By using echo-sounding data and considerable local knowledge of the environment the possibility to use data from Landsat TM for bathymetric mapping is analysed in the vicinity of Zanzibar. Different TM band combinations and basic image processing techniques are evaluated against the known water depths. The limitations of remote sensing techniques for bathymetric mapping are discussed, with emphasis on the problem of differences in reflective properties of the sea bottom. A recommendation for an optimal empirical method is given.  相似文献   

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