Relational spatial topologies for historical geographical information

Abstract

Research on time and data models for Geographical Information Systems (GIS) has focused mainly in the representation of temporal geographical entities and implementation of temporal databases. Many temporal GIS database structures have been proposed but most of them just provide principles, not the recipe for the design. Owing to the manipulation of the large quantity of geographical information and the slow response time, few implementations exist. This paper presents a relational method of storing and retrieving spatial and temporal topologies. Two-level state topologies are proposed: a state topology for a set of geographical entities and a state topology for a single geographical entity.

From a temporal perspective, these two-level state topologies may also be viewed as two-level time topologies: a time topology for all geographical entities in a GIS database and a time topology for a single geographical entity. Based on these state and time topologies, a detailed storage approach for historical geographical information is provided.     

Editorial

Abstract

The analysis of geographical information is compared with other production processes in which a user can only accept an end-product if it meets certain quality requirements. Whereas users are responsible for defining the levels of quality they need to use the results of the analyses of geographical information systems in their work, database managers, experts and modellers could greatly assist users to achieve the quality of results they seek by formalizing information on: (1) data collection, level of resolution and quality; (2) the use of the basic analytical functions of the geographical information system; and (3) the data requirements, sensitivity and error propagation in models. These meta-data could be incorporated in a knowledge base alongside the geographical information system where, together with procedures for on-line error propagation, a user could be advised on the best way to achieve a desired aim. If the analysis showed that the original constellation of data, methods and models could not achieve the aim with the desired quality, the intelligent geographical information system would present a range of alternative strategies—better methods, more data, different data, better models, better model calibration, or better spatial resolution—and their costs by which the user's aims could reasonably be achieved.     

Fuzzy representation of geographical boundaries in GIS

Abstract

Polygon boundaries on thematic maps are conventionally considered to be sharp lines representing abrupt changes of phenomena. However, in reality changes of environmental phenomena may also be partial or gradual. Indiscriminate use of sharp lines to represent different types of change creates a problem of boundary inaccuracy. Specifically, in the context of vector-based GIS, use of sharp lines to represent gradual or partial changes may cause misunderstanding of geographical information and reduce analysis accuracy.

In this paper, the expressive inadequacy of the conventional vector boundary representation is examined. A more informative technique—the fuzzy representation of geographical boundaries—is proposed, in which boundaries describe not only the location but also the rate of change of environmental phenomena. Four methods of determining fuzzy boundary membership grades from different kinds of geographical data are described. An example of applying the fuzzy boundary technique to data analysis is presented and the advantages of the technique are discussed.     

Thematic signatures for cleansing and enriching place-related linked data

There has been significant progress transforming semi-structured data about places into knowledge graphs that can be used in a wide variety of geographic information systems such as digital gazetteers or geographic information retrieval systems. For instance, in addition to information about events, actors, and objects, DBpedia contains data about hundreds of thousands of places from Wikipedia and publishes it as Linked Data. Repositories that store data about places are among the most interlinked hubs on the Linked Data cloud. However, most content about places resides in unstructured natural language text, and therefore it is not captured in these knowledge graphs. Instead, place representations are limited to facts such as their population counts, geographic locations, and relations to other entities, for example, headquarters of companies or historical figures. In this paper, we present a novel method to enrich the information stored about places in knowledge graphs using thematic signatures that are derived from unstructured text through the process of topic modeling. As proof of concept, we demonstrate that this enables the automatic categorization of articles into place types defined in the DBpedia ontology (e.g., mountain) and also provides a mechanism to infer relationships between place types that are not captured in existing ontologies. This method can also be used to uncover miscategorized places, which is a common problem arising from the automatic lifting of unstructured and semi-structured data.     

Spatiotemporal data model for network time geographic analysis in the era of big data

There has been a resurgence of interest in time geography studies due to emerging spatiotemporal big data in urban environments. However, the rapid increase in the volume, diversity, and intensity of spatiotemporal data poses a significant challenge with respect to the representation and computation of time geographic entities and relations in road networks. To address this challenge, a spatiotemporal data model is proposed in this article. The proposed spatiotemporal data model is based on a compressed linear reference (CLR) technique to transform network time geographic entities in three-dimensional (3D) (x, y, t) space to two-dimensional (2D) CLR space. Using the proposed spatiotemporal data model, network time geographic entities can be stored and managed in classical spatial databases. Efficient spatial operations and index structures can be directly utilized to implement spatiotemporal operations and queries for network time geographic entities in CLR space. To validate the proposed spatiotemporal data model, a prototype system is developed using existing 2D GIS techniques. A case study is performed using large-scale datasets of space-time paths and prisms. The case study indicates that the proposed spatiotemporal data model is effective and efficient for storing, managing, and querying large-scale datasets of network time geographic entities.     

GIS and geometric representation in facility location problems

Abstract

A neglected aspect of facility location problems is the geometric representation of the facilities sited and clients served. Point objects represent these entities in most facility location problems. This can cause solution error and limit the range of potential solutions. The increasing capabilities of geographical information systems (GIS) to represent, store and manipulate spatial entities provides a substantial but unrealized potential for more sophisticated geometric representation in facility location problems. This paper provides a framework for realizing this potential. Specifically, this paper: (i) synthesizes existing formulations; (ii) develops a unified mathematical framework; (iii) identifies feasible computational strategies that can be implemented within a GIS framework, and; (iv) discusses potential GIS-based solution algorithms.     

Natural trees—neighbourhood-location in a nutshell

Abstract

We present the notion of a natural tree as an efficient method for storing spatial information for quick access. A natural tree is a representation of spatial adjacency, organised to allow efficient addition of new data, access to existing data, or deletions. The nodes of a natural tree are compound elements obtained by a particular Delaunay triangulation algorithm. Improvements to that algorithm allow both the construction of the triangulation and subsequent access to neighbourhood information to be O(N log N). Applications include geographical information systems, contouring, and dynamical systems reconstruction.     

Aspects of the implementation of the GEOVIEW design

Abstract

GEOVIEW, an integrated system, uses relational database technology and a graphics package (Graphical Kernel System) to offer a flexible environment in which to develop applications of geographical information systems (GIS). It has facilities to represent data in different spatial data structures. Data are stored and retrieved efficiently by using variable length raw data. The unified representation offers the benefit of storing entities in a single relation and eases the process of overlaying different entities. GEOVIEW also provides a mechanism for tailoring user interfaces to suit the needs of different applications by means of a facility to generate macros and menus.

Processing requirements for GIS applications can be supported by using tools provided by relational database technology and by graphics packages. High-level language interfaces which can process dynamic statements and bind dynamic variables are needed to develop an efficient database interface module. A graphics segment facility is essential to provide editing functions and to maximize the use of the local processing power of graphics workstations in the graphics interface module. Further improvements in performance can be made by using the array fetch facility and linear keys for spatial searching.     

Remotely-sensed data as an information source for geographical information systems in natural resource management a review

Abstract

Remotely-sensed image data have long served as a primary source of information for. geographical information systems (GIS), with the transformation of data to information provided by visual image interpretation. Digital image data, in combination with recent advances in computer technology, currently allow visual image interpretation to be realised in a completely digital processing environment. However, it remains desirable to capitalize even further on the potential of digital image data for GIS, through the use of schemes involving automated data processing. The opportunities for, and impediments to, such schemes are considered here with particular reference to the provision of information for natural resource management. It is concluded that further—although foreseeable—developments in both research and technology will be required before fully operational procedures for the automated acquisition of GIS information from image data can be established.     

A spatial data model design for feature-based geographical information systems

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.     

A Pedagogic Framework to Link GIS to the Intellectual Core of Geography

Abstract

This paper aims to develop a new pedagogic framework for teaching GIS at the college and university level using Berry's geographic matrix. By synthesizing different schools of thought, this paper argues that GIS education essentially involves two aspects—how to teach about GIS and how to teach with GIS. Berry's geographic matrix can be used to tie these dual aspects of GIS education together neatly. As an abstract representation of geographical phenomena, the geographic matrix embeds all three entities of GIS—location, attribute, time—and thus can help GIS instructors teach about GIS. As a synthesis of geographical approaches, the geographic matrix can assist GIS instructors teach with GIS. This paper demonstrates that GIS is actually an implementation of Berry's geographic matrix. Furthermore, the 10 approaches to geographical analysis, originally proposed by Berry for the geographic matrix, can be executed routinely in a GIS environment. By incorporating Berry's geographic matrix into GIS education, teachers can enable students to surpass technical issues and to appreciate the conceptual and functional linkages between GIS and geography's intellectual core.     

Multi-criteria modelling and clustering of spatial information

To improve the formal integration of verbally given spatial information in a geographical information system, a methodology for converting such information to a geographical representation was developed. This was applied to examples of a spatial-related analysis of natural language text messages in the domain of disaster management. This article presents an approach for such a conversion by using a suitable knowledge representation as well as formal modelling structures. The structures are provided by an ontology-supported knowledge base. With respect to spatial uncertainty, a formal representation based on possibility theory was defined. Moreover, a cluster algorithm was developed for handling information of different sources and building a spatial context.     

SPIDER—an interactive statistical tool for the analysis of spatially distributed data

Interactive statistical graphics are reviewed in the contexts of spatial data and geographical information systems (GIS). GIS provide the user with an active geographical view of the data—a map that can be used as an entry point to the data base. Prototype software—SPIDER—illustrates the possibilities of using statistical graphics as further views of the data, which can be made active and thus provide alternative means of querying the data. These views can be cross-referenced by 'linking'. It is argued that such a system can provide a very rich environment for pursuing exploratory statistical analysis of spatial data.     

Quadtree storage of vector data†

Abstract

Vector data storage has various advantages in a cartographic or geographical information system (GIS) environment, but lacks internal spatial relationships between individual features. Quadtree structures have been extensively used to store and access raster data. This paper shows how quadtree methods may be adapted for use in spatially indexing vector data. It demonstrates that a vector quadtree stored in floating point representation overcomes the classical problem with raster quadtrees of data approximation. Examples of vector quadtrees applied to realistic size data sets are given     

Ontologies of geographic information

This article explores the notion of a system of ontologies specifically designed for the needs of an information science. A framework for geographic information ontologies is outlined that focuses on geographic information constructs rather than on the direct representation of real-world entities or on linguistic terms. The framework takes the form of a generative hierarchy anchored by the notion of intentionality at one end and of a spatiotemporal field of potentially relevant information at the other. Two theoretical notions are used in the generation of the hierarchy. The first is the principle of semantic contraction, whereby, starting from a level of geographic information constructs specified so as to reflect user intentionality, semantically coherent domains of properties are removed over several steps until only the rudiments of a spatiotemporal information system are left. The second notion is that of object of discourse, which allows entities to be represented as the composites of geographic information constructs at the higher levels of the hierarchy, explicitly reflecting the connections between the purpose, function, appropriate internal constitution, and ensuing categorization of the entities represented. The framework's main contribution is thus twofold: first, it allows the notions of user purpose and object function to be directly built into geographic representations; second, it proposes a hierarchy of ontological levels that are linked by systematic semantic relations. Further, the framework presents an integrated view of object and field representations. It may also provide a novel perspective on a number of issues of ongoing interest in geographic information science.     

Calibrating a Land Parcel Cellular Automaton (LP-CA) for urban growth simulation based on ensemble learning

The reliability of raster cellular automaton (CA) models for fine-scale land change simulations has been increasingly questioned, because regular pixels/grids cannot precisely represent irregular geographical entities and their interactions. Vector CA models can address these deficiencies due to the ability of the vector data structure to represent realistic urban entities. This study presents a new land parcel cellular automaton (LP-CA) model for simulating urban land changes. The innovation of this model is the use of ensemble learning method for automatic calibration. The proposed model is applied in Shenzhen, China. The experimental results indicate that bagging-Naïve Bayes yields the highest calibration accuracy among a set of selected classifiers. The assessment of neighborhood sensitivity suggests that the LP-CA model achieves the highest simulation accuracy with neighbor radius r = 2. The calibrated LP-CA is used to project future urban land use changes in Shenzhen, and the results are found to be consistent with those specified in the official city plan.     

Data structures for three-dimensional spatial information systems in geology

Abstract

The accumulation of geological information in digital form, due to modern exploration methods, has introduced the possibility of applying geographical information system technology to the field of geology. To achieve the benefits in information management and in data analysis and interpretation, however, it will be necessary to develop spatial models and associated data structures which are specifically designed for working in three dimensions. Some progress in this direction has already been demonstrated, with the application of octree spatial subdivision techniques to the storage of uniform volume elements representing mineral properties. By imposing octree tessellations on more precisely-defined geometric data, such as triangulated surfaces and polygon line segments, it may now be possible to combine efficient spatial addressing with topologically-coded boundary representations of geological strata. The development of storage schemes capable of representing such geological boundary models at different scales poses a particular problem, a possible solution to which may be by means of hierarchical classification of the vertices of triangulated surfaces according to shape contribution.     

时空数据模型的研究现状与展望

分析了时空表达与建模理论的5个发展阶段:基于静态数据模型扩展、面向对象表达、基于对象变化(事件序列)、时空集成和以过程为核心的时空数据模型;阐述了时空数据模型在时空动态语义、地理时空认知表达和地球信息科学解决的基本问题方面的研究现状,并指出由于现有时空数据模型主要以地理实体存在状态的"对象视图"或"事件视图"(而不是演变特性的"过程视图")作为表达载体,割裂了其内在联系,无法实现复杂地理实体的时空语义描述和动态过程分析。最后,提出以地理实体演变为核心的时空语义描述方法和融入地理对象、变化机制、对象变化的时空动态表达将是时空表达与建模理论的发展趋势。     

Organization of Feature-, Time-, and Location-Based Mental Models

This study considers how mental models are encoded into memory by viewing visual displays like maps. A mental model is an internal representation of a situation that links objects or concepts to other objects or concepts. Previous studies indicated location-based mental models are encoded when a series of propositional statements such as the object is in the location are read from a text. Evidence that locations were being used as the basic container for an organization of mental models is provided by a significant fan effect. A fan effect shows an increase in reaction time with the number of models considered when making a decision. Features, times, and locations were considered as possible containers in the mental models. Subjects created location-based mental models, but also encoded feature-based mental models. A reverse fan effect for time, found for a map animation, suggested the order of the presentation of maps could greatly affect the structure of learned information.