Incorporating Cellular Automata simulators as analytical engines in GIS

Contemporvy GIS suffer from a variety of problems. These include poor ability to handle dynamic spatial models, poor performance for many operations, and poor handling of the temporal dimension. Cellular Automata (CA) are dynamic mathematical systems based on discrete time and space. While CA have many similarities to GIS, and indeed excel in many areas in which GIS are deficient, they cannot themselves be considered as GIS since they lack the necessary sophisticated Capabilities in data input, data storage and retrieval, and data output. However, the advantages of CA in data analysis and modelling are significant. In order to exploit fully the advantages of each system - GIS and CA - we have developed a methodology and prototype system for coupling GIS and CA, in which the CA serves as an alternative analytical engine for the GIS. In the prototype system, spatial, temporal (i.e. time series), and spatio-temporal filters as well as spatial diffusion operators are developed. In addition, the integrated system provides a flexible framework for the programming and running of dynamic spatial models. We conclude that CA represent a viable alternate analytical engine for GIS and provide increased ability for dynamic spatial modelling within GIS.     

GIS-based simulation as an exploratory analysis for space-time processes

The purpose of this paper is to argue for a novel use of geographical information system (GIS) as an exploratory device for understanding complex space-time processes. Conventionally, a GIS has been configured as a spatial database management system. Therefore, the capabilities of data input, storage, retrieval, manipulation and display have been well developed, whereas the analytical and dynamic processing and modelling capabilities are under-developed. The importance of integrating GIS with dynamic and analytical models has been widely recognised. Extending the use of GIS into spatial simulation represents a plausible research direction. On the other hand, the usefulness of conventional deductive model becomes limited when dealing with complex space-time processes. In essence, the inherent complexity calls for a simulation approach. The new nonlinear modelling paradigm, for example, cellular automata (CA), opened a way in which behaviourally-richer dynamics and more micro-spatial data could be incorporated into understanding space-time processes. It is argued therefore that GIS can be used as a platform – a controlled environment or laboratory – for exploring complex space-time processes. The discussion of GIS-based simulation in this paper is illustrated with a primitive simulation of the evolution of urban spatial structure. Received: 2 July 1997/Accepted: 19 November 1998     

Simulation Modelling Applied to Runoff Modelling Using MapScript

Dynamic spatial analysis addresses computational aspects of space–time processing. This paper describes the development of a spatial analysis tool and modelling framework that together offer a solution for simulating landscape processes. A better approach to integrating landscape spatial analysis with Geographical Information Systems is advocated in this paper. Enhancements include special spatial operators and map algebra language constructs to handle dispersal and advective flows over landscape surfaces. These functional components to landscape modelling are developed in a modular way and are linked together in a modelling framework that performs dynamic simulation. The concepts and modelling framework are demonstrated using a hydrological modelling example. The approach provides a modelling environment for scientists and land resource managers to write and to visualize spatial process models with ease.     

Control of spatial discretisation in coastal oil spill modelling

Spatial discretisation plays an important role in many numerical environmental models. This paper studies the control of spatial discretisation in coastal oil spill modelling with a view to assure the quality of modelling outputs for given spatial data inputs. Spatial data analysis techniques are effective for investigating and improving the spatial discretisation in different phases of the modelling. Proposed methods are implemented and tested with experimental models. A new “Automatic Search” method based on GIS zone design principles is shown to significantly improve discretisation of bathymetric data and hydrodynamic modelling outputs. The concepts and methods developed in the study are expected to have general relevance for a range of applications in numerical environmental modelling.     

基于空间行为的面向对象空间数据模型

本文根据面向对象空间数据模型的相关概念和特点,将地理空间中的空间行为进行建模后纳入面向对象空间数据模型的框架中。面向对象空间数据模型由数据模型和空间行为模型两个部分组成:数据模型包括空间特征数据和属性特征数据;同时将空间行为模型分为两大类,即静态空间行为模型(地理目标间关系)和动态行为模型(地理目标行为)两部分。在此框架提出的基础上,本文利用二进制、XML流等格式文件对该空间数据模型进行了整合和组织。     

时空一体化GIS-T数据模型与应用方法

在介绍与交通地理信息系统(GIS for transportation,GIS-T)相关的概念的基础上,归纳了GIS-T数据模型的发展和已经取得的主要成果,重点讨论了时空一体化GIS-T数据模型的基本框架。该模型着重解决了动态交通信息与道路网几何数据的一体化时空建模问题,并且进一步分析了GIS-T的基本技术方法,探讨了GIS-T的若干典型应用,并对该方向今后的研究进行了分析和展望。     

Part 3 Specialized aspects of GIS and spatial analysis

GIS and spatial analysis is suited mainly for static pictures of the landscape, but many of the processes that need exploring are dynamic in nature. Dynamic processes can be complex when put in a spatial context; our ability to study such processes will probably come with advances in understanding complex systems in general. Cellular automata and agent-based models are two prime candidates for exploring complex spatial systems, but are difficult to implement. Innovative tools that help build complex simulations will create larger user communities, who will probably find novel solutions for understanding complexity. A significant source for such innovations is likely to be from the collective efforts of hobbyists and part-time programmers, who have been dubbed “garage-band scientists” in the popular press.     

Use of a Three-Domain Repesentation to Enhance GIS Support for Complex Spatiotemporal Queries

As the development of Geographic Information Systems (GIS) proceeds to advanced scientific and societal applications, there is an emerging need to enhance GIS support for complex spatiotemporal queries. Dynamic GIS representations (as opposed to static, map-based representations) that can integrate proper data elements in the production of geographic information are required. This paper demonstrates the use of a three-domain representation that facilitates compilation of higher-level information (such as frequency and rate) from preliminary data records (such as time and location) stored in a database. The three-domain representation is compared with snapshot, space-time composite, and spatiotemporal object models using a sample data set for forest transitions. While the three-domain representation is a normalization of these data models, it offers a conceptual alternative that enables GIS to represent spatiotemporal behaviors of geographic entities, in addition to entities as well as histories at locations as emphasized in most GIS data models. The comparison shows that the three-domain representation has combined the strengths of the space-time composite and spatiotemporal object models. Moreover, it enables aggregations of analytical use along with dynamic mappings between geographic concepts and locations, a distinct capability that takes GIS query processing beyond the level of information support offered by static map-based data models.     

Fields as a framework for integrating GIS and environmental process models. Part 1: Representing spatial continuity

Linking a GIS to a spatially distributed, physically-based environmental model offers many advantages. However, the implementation of such linkages is generally problematic. Many problems arise because the relationship between the reality being represented by the mathematical model and the data model used to organize the spatial data in the GIS has not been rigorously defined. In particular, while many environmental models are based on theories that assume continuity and incorporate physical fields as independent variables, current GISs can only represent continuous phenomena in a variety of discrete data models. This paper outlines a strategy in which field variables are used to enable modellers to work directly with the spatial data as spatially continuous phenomena. This allows the manner in which the spatial data has been discretized and the ways in which it can be manipulated to be treated independently from the conceptual modelling of physical processes. Modellers can express their spatial data needs as representations of reality, rather than as elements of a GIS database, and a GIS-independent language for model development may result. By providing a formal linkage between the various models of spatial phenomena, a mechanism is created for the explicit expression of transformation rules between the different spatial data models stored and manipulated by a GIS.     

A classification of water erosion models according to their geospatial characteristics

In this article, an extensive inventory in the literature of water erosion modelling from a geospatial point of view is conducted. Concepts of scale, spatiality and complexity are explored and clarified in a theoretical background. Use of Geographic Information Systems (GIS) is pointed out as facilitating data mixing and model rescaling and thus increasing complexity in data-method relations. Spatial scale, temporal scale and spatial methodologies are addressed as the most determining geospatial properties underlying water erosion modelling. Setting these properties as classification criteria, 82 water erosion models are identified and classified into eight categories. As a result, a complete overview of water erosion models becomes available in a single table. The biggest share of the models is found in the category of the mechanistic pathway-type event-based models for watershed to landscape scales. In parallel, geospatial innovations that could be considered as milestones in water erosion modelling are highlighted and discussed. An alphabetical list of all models is also listed in the Appendix. For manipulating scale efficiently, two promising spatial theories are suggested for further exploitation in the future such as hierarchy theory and fractals theory. Regarding erosion applications, uncertainty analysis within GIS is considered to be necessary for further improving performance of erosion models.     

景观空间感知评价的GIS方法应用研究

景观空间感知是在空间范畴内人与景观相互作用的结果,研究观察者对于景观环境空间信息的获取过程与感知阈值。强调景观美学价值与空间感知度的统一,对景观空间设计与观景位置的选择具有现实指导意义。然而,目前对与景观空间感知的研究还处于刚刚起步阶段,并未形成一套完整的科学体系。笔者在景观空间感知理论发展进程的基础上,总结景观空间感知理论的研究内容与研究方法,基于GIS 3维空间分析进行了景观空间感知评价的方法研究,提出将地理信息系统技术与虚拟现实相结合,利用VRGIS对景观空间感知环境进行模拟与定量化分析,为建立完整空间感知评价体系提供方法理论支撑。     

Dynamic Modelling and Visualization on the Internet

There is a growing requirement for GIS to incorporate dynamic analytic models. At the same time, there is a need to distribute results of dynamic GIS using the Internet. Therefore, this paper sets out to explore the implementation of dynamic environmental models using Internet-based geocomputation techniques. An overview discusses shortcomings of current Internet GIS techniques for dynamic modelling based on the idea that bidirectional and sustained communication is required between the client and the server sides. Thus an applet-servlet approach is explored to demonstrate the modelling process of a chosen hydrological model, TOPMODEL, which requires frequent and efficient client-server interactions. This approach overcomes the inherent shortcomings of the current Common Gateway Interface (CGI) and more primitive Java applet techniques. We present an effective and generic way to implement dynamic modelling and visualization processes in an Internet environment. This allows users to benefit from Internet-based geocomputation techniques to gain insights into computation and representation of dynamic spatial phenomena.     

Tessellations in GIS: Part I—putting it all together

This article attempts to describe the role of tessellated models of space within the discipline of geographic information systems (GIS)—a speciality coming largely out of geography and land surveying, where there was a strong need to represent information about the land’s surface within a computer system rather than on the original paper maps. We look at some of the basic operations in GIS, including dynamic and kinetic applications. We examine issues of topology and data structures and produce a tessellation model that may be widely applied both to traditional “object” and “field” data types. Based on this framework, it can be argued that tessellation models are fundamental to our understanding and processing of geographical space, and provide a coherent framework for understanding the “space” in which we exist. This first article examines static structures, and a subsequent article looks at “change”—what happens when things move.     

An integrated representation of spatial and temporal relationships between evolving regions

 The study of relationships between evolving regions within GIS still needs the development of operators that integrate the spatial and temporal dimensions. This paper introduces a new approach that combines topological relationships between regions in 2-dimensional space with temporal relationships between convex intervals in time. Resulting relationships are defined and visually presented within a 3-dimensional space that integrates the geographical space as a 2-dimensional space and the time line as the third dimension. Conceptual neighbourhoods are identified and extended by the concept of semi-transitions and transitions. Such a flexible framework presents the advantage of being derived from accepted relationships in both space and time. Its computational implementation is therefore compatible with current spatial and temporal GIS models. Received: May 2000 / Accepted: June 2001     

水利信息系统中的GIS技术

阐述了一种新的GIS理论成果:大型GIS与数字地球的空间数学基础理论,该理论克服了传统空间数学基础理论的不足。以该理论为理论基础并结合水利信息系统的实际需求运用GIS技术支持下矢栅结合的技术,提出了将数字栅格地图(DRG)作为专业信息系统的参考背景,用户关心的专业实体适时标注的防汛信息系统建设技术路线,该技术路线具有良好的实施前景。同时本文就系统中若干关键技术的设计与实现做了详细阐述。     

GIS时空分析系统的Clifford代数设计与实现

以Clifford代数为理论基础与数学工具,构建了时空分析原型系统：①在兼容多类常用GIS数据格式的基础上,根据Clifford代数空间构建的思想,对现有时空数据模型进行扩展,实现了时间、空间与属性的一体化表达;②定义了可支撑多维度时空分析的几何、度量等Clifford代数算子库;③基于插件的时空分析模型算法构建及集成框架,实现了高维邻域分析、网络分析以及时空栅格数据分析等地学分析算法。实验结果显示,根据Clifford代数所构建的时空分析系统可有效支撑多维时空分析。     

空间染色镶嵌模型理论与应用

地理空间数据模型及其对地理对象-空间关系的描述是地理信息科学（GIS）理论与应用研究的核心内容。介绍和讨论了一种新的GIS空间数据模型—空间染色模型（spatial chromatic model,SCM）的结构、操作、应用及其在地理学上的含义。SCM的特点是其每个基础数据单元（细胞）具有一个唯一的编码,这些编码提供了面向各种GIS空间分析和运算的丰富信息。SCM的本质是一种基于实体第一性的相对性地理空间,它有助于从一个新的视角更加深入地理解地理实体-空间关系。     

Database structure for the integration of RS with GIS based on semantic network

The integration of remote sensing (RS) with geographical information system (GIS) is a hotspot in geographical information science. A good database structure is important to the integration of RS with GIS, which should be beneficial to the complete integration of RS with GIS, able to deal with the disagreement between the resolution of remote sensing images and the precision of GIS data, and also helpful to the knowledge discovery and exploitation. In this paper, the database structure storing the spatial data based on semantic network is presented. This database structure has several advantages. Firstly, the spatial data is stored as raster data with space index, so the image processing can be done directly on the GIS data that is stored hierarchically according to the distinguishing precision. Secondly, the simple objects are aggregated into complex ones. Thirdly, because we use the indexing tree to depict the relationship of aggregation and the indexing pictures expressed by 2-D strings to describe the topology structure of the objects, the concepts of surrounding and region are expressed clearly and the semantic content of the landscape can be illustrated well. All the factors that affect the recognition of the objects are depicted in the factor space, which provides a uniform mathematical frame for the fusion of the semantic and non-semantic information. Lastly, the object node, knowledge node and the indexing node are integrated into one node. This feature enhances the ability of system in knowledge expressing, intelligent inference and association. The application shows that this database structure can benefit the interpretation of remote sensing image with the information of GIS.     

DATABASE STRUCTURE FOR THE INTEGRATION OF RS WITH GIS BASED ON SEMANTIC NETWORK

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