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  • 2004 Volume 6 Issue 4
    Published: 25 December 2004
      
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  • ARTICLES
    National Earth Observation System and Remote Sensing Science and Technology
    LI Shukai
    2004, 6(4): 5-10.
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    Remote sensing is a kind of science and technology with strong applications background. This paper states that serving national developing strategy is an important embodiment of remote sensing contribution to the society from the original intention of remote sensing development and today's outstanding achievement. A basic framework of technological system of earth observing technology by remote sensing at national level and the design idea of " Four major integration system" are put forward, This paper discusses the nature and characteristics of remote sensing technology and the relations among the basis, technology, application, product and system engineering issues. It is the development direction of remote sensing that tasks impel subjects.
  • ARTICLES
    The Design and Implementation of Environmental Monitoring WebGIS
    HUANG Binghu, LV Guonian, LIU Ernian, ZHANG Qiang
    2004, 6(4): 11-14.
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    This paper begins with the problem of how to manage the dynamic environmental monitoring point layers. It firstly points out that something must be considered for meeting the requirement of managing the dynamic layers. Such as, how to solve the problem when many clients visit the server simultaneously, and how to save the session information of the clients individually.Thinking the above problems, this paper gives some primary class diagrams based on Unified Modeling Language and describes the function and relationship of the diagrams, which can accelerate the software development based on the UML tool. The server end includes the classes like MapX, MapXServer, MapXbroker and some other classes. Each class has its own function, some relationships among the classes have been given. The system developing environment adopts the Microsoft .NET, for the .NET is easier and faster to develop the software.
  • ARTICLES
    Some Considerations about Digital Earth and Geographical Sciences
    LI Shuang
    2004, 6(4): 15-18.
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    Through several years development, the conception and connotation of digital earth have been enriched and taken shape, in the meantime, they have also exerted profound impact on all disciplines of natural sciences. Based on the research contents and methods of the earth system science and geographical sciences, the research on effect of man-land relationship that digital earth produced has been discussed in this paper. Under the new technical framework, earth system science investigates the new man-land relationship, which is the main content of the digital earth and has become the necessary theoretical and technical bases of modern geographical sciences. In digital earth laboratory, we can realize the aim of providing a virtual innovation environment for the original innovation. The geographical sciences' virtual innovation environment takes data of different spatial and temporal resolutions, as basis, or megal data produced by fusing data about resource, environment, society, economy and population. These data are disposed from lithosphere to biosphere, to atmosphere, from regional level to global level, and from infer space to outer space which abide by a given geographical coordinate.The new technical system will be a fine resolution of the complex big system. The research can finish the actuality description, historical restoration and future prognostication through the knowledge innovate platform.
  • ARTICLES
    Designing and Mapping of 1∶1 000 000 Landscape Ecologic Maps of China
    CHENG Weiming, CHAI Huixia, LONG En, LIU Haijiang, ZHANG Yang
    2004, 6(4): 19-24.
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    Based on advanced techniques such as Remote Sensing, Geographical Information System and Computer-aided cartography etc., this paper presents the significance and actual progress in landscape ecologic mapping at home and abroad, discusses traditional mapping methods and mapping criterion on thematic maps, design on modern computer automatic mapping method, map contents and mapping procedure of landscape ecologic maps. The mapping contents includes: (1) probing into or researching new mapping method and mapping criterion based on RS and GIS; (2) researching classification indexes and classification system; (3) researching and designing modern computer automatic mapping method and technology; and (4) finishing and publishing the 1∶1000 000 landscape ecologic maps of China, and mapping manuals etc. The research steps include research historical analysis of the study area, basic database construction, analysis of regional landscape characteristics, landscape classification and mapping, and finial integrated mapping. The maps of landscape ecology include 8 formats, the first one is color terrain map based on 1∶250 000 DEM and mapping explanation, the second-third one is ETM imageries in 2000, including typical field photographs and geologic profiles, the fourth-fifth one is characteristics analysis of several key areas, the sixth-seventh one is the main type map of landscape ecology, including classification system and legend system, and the last one is function division map of key areas. Based on traditional classification systems of vegetation, LUCC and FAO, the thesis integrates two important indexes of relief and land cover, and presents new landscape classification system.The study breaks traditional thematic mapping method of single elements, which can provide method of presupposition for finishing the 1∶1 000 000 landscape ecologic maps of China in future and integrate scientific research with productive practice. It can not only update actual basic materials based on RS data, present actual status of the study area, but also discuss ecological environmental problems, present reconstructing methodology or measures. So, the study has theoretical importance and practical application value.
  • ARTICLES
    Integrated and Reconstructed Fujian Provincial Government Affair Information Sources
    XIAO Guirong, WANG Qinmin, TU Ping, CHEN Chongcheng
    2004, 6(4): 25-29.
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    It is significant to integrate and standardize the government affair information sources in the process of implementing electronic government. In this study, we analyzed the digital situation of Fujian provincial government affair information sources, then brought forward a series of criterion, classification system, exchange means and service modes for information standardizing and sharing in digital Fujian project. In order to integrate those differently-constructed databases which were divided into spatial database, relation database, file data and multimedia database and were distributed on each office or each profession, we designed and developed an electronic government sharing system in Fujian province based on XML Web services technology. The system made best use of the advantage of Web services which were used to transform all kinds of data into XML format, then integrate data with application system. The result of this study achieves integration of information and application, and improves the level of government affair information sharing utilization and service.
  • ARTICLES
    Integrated Data Management in Digital City
    GU Jirong, MIAO Fang, WANG Chengshan
    2004, 6(4): 30-32.
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    The data management has changed enormously as companying with the development of the Information technology. It changed from structured data management to non-structured data management. This change leads to many new problems and challenges. Metadata works importantly in information sharing system. Metadata can avoid the repeatedly data construction and conform information sharing between different data supply departments. The information mining technology based on agent was proposed, and the integrated data management was designed and developed. With the help of intelligent search tactics modeling, the quick search of metadata base, the quick download of the data, the mutual preview of the data and information cache were realized. In this paper, we discuss the data management in digital Chengdu based on metadata and intelligent agent.
  • ARTICLES
    Preliminary Study on the Structure and Function of Information System for Anqing Wetland
    WANG Jinghua, ZHOU Binggen, WANG Xinyuan
    2004, 6(4): 33-36,84.
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    Wetland is not only an important land resource but also a source of human production and living materials utilize wetland resources. It is of great significance to the utilization of GIS, RS and GPS technology on the whole, to study how to scientifically manage and rationally use wetlands. The wetland in Anqing is distributed in the north bank of the Yangtze River, the largest in distribution in Ahhui province. It covers an area of 9.87×104hm2 being mainly composed of four lakes. It has invaluable function to conserve biological diversity and scarce species. At the same time, it is also a typical region to study the development and restoration of the lake wetland under the influence of human activities. Anqing wetland information system has two kinds of structure, one is logical, the other is functional. Database is the core, which is comprised of attribute data and special data. Information of the system comes from on-the-spot survey, statistical datum and remote sensing image and so on. In this paper, the structure of the system, design principle and function are preliminarily discussed in order to provide a new method for Anqing wetland research and management.
  • ARTICLES
    The Design and Implementation of Jinsha River in Yunnan Province:Ecological Conservation and Construction DSS
    WU Sheng, HUA Yixin, YANG Shuhua, LI Huiguo, LI Yonghong
    2004, 6(4): 37-40.
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    Jinsha river basin suffers from most serious soil and water loss among the six large watersheds in Yunnan province. To establish the Ecological Conservation and Construction decision-supporting system (DSS) in the river basin is of vital importance to the protection of resources and the local government's decision making through using the technology of GIS to capture, manage, analyze and apply eco-geographic information. This paper mainly discusses the application characteristics, architecture, and implementation of the project, namely, Jinsha River in Yunnan Province:Ecological Conservation and Construction DSS. Ecologists used to research the ecological status quo and transformation by measuring and analyzing with simple tools in paper maps and forms. But in ecological conservation and construction DSS, the GIS technology was introduced to overlay all kinds of eco-related information on 1∶250,000 and 1∶50,000 E-maps and TM images, spatial data and attributes data were uniformly managed to support decision for ecological conservation. Based on territorial ecological research, we developed and described an effective spatial analysis model for natural forest preservation by converting cultivated land into forest. The design and implementation of territorial ecological evaluation and forecast function was also introduced in this paper.
  • ARTICLES
    A Major Break in Geographical History of China——Taking Account of Geography Section of History in the Han Dynasty
    SUN Guanlong
    2004, 6(4): 41-44.
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    Before Qin Dynasty geography had a tradition of inspecting the nature and research the nature, and great success had gained. From Qin and Han dynasties, Chinese ancient geography lost this tradition, the first ancestor is Ban Gu in Eastern Han Dynasty. Dong Zhongshu in Western Han Dynasty advanced a theory of rejecting the Various Schools, monopolizing the Confucian School. It excluded or strangled other Various Schools,and destroyed a tradition of laying stress on nature in the Confucian School. Ban Gu wrote Geography Section of History in the Han Dynasty, in which he submitted to trend at that time,overlooked the tradition of laying stress on nature during pre-Qin period, vested the geograthy with other meanings, took record of establishment and evolution of administrative division in domination, and took mountains and rivers of natural knowledge as dependency, cause later Chinese ancient geography to follow the road of putting stress on evolution and textual research of geography, as well as recording the social history and the social condition. These gradually formed a Chinese traditional geography focusing on the study of historic geography, economic geography and evolution geography. This is a major break in geographical history of China between pre-Qin times and Qin and Han dynasties. This break directly affected the achievements of the Chinese ancient geography, making the Chinese ancient geography fail to evolve into modern geography.
  • ARTICLES
    The Relevancy Between Quantitative Terrain Factors and Mean Slope in China′s Loess Plateau
    ZHANG Ting , TANG Guoan, WANG Chun, WANG Zheng, LONG Yi
    2004, 6(4): 45-50.
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    Different terrain factors express the undulating characteristics and spatial variations of the true surface from different aspects. The relationships among them can play a key role in revealing the mechanism and development of the terrain and geomorphologic situation to a great extent. The relationships and their variance discipline between the terrain factors and mean slope are discussed in this paper via the Back Propagation model of Neural Network. Fifteen loess gully-hilly areas are selected as the test areas for experiment, and the relevant 1∶10 000 and 1∶50 000 map scale DEMs of high resolution and high precision are also selected as the basic data. The results show this method can effectively evaluate the relevancy of terrain factors on the mean slope extracted from DEMs at the two scales. It is hoped that this result can be helpful in evaluating the availability of the DEM scale applied, determining the relevancies among multiple topographical factors as well as selecting suitable terrain variables for different applications.
  • ARTICLES
    Analysis of the Latest Research and Improvement of Universal Soil Loss Equation
    ZHANG Zhaolu, CUI Jihong
    2004, 6(4): 51-55.
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    Universal Soil Loss Equation (USLE) is an empirical model widely used in the domain of soil erosion by water. Although USLE has a simple structure, the result of the model can reach the requirement for soil erosion prediction under certain precision with less input data. The improvement of USLE includes the expansion of application scope, the enhancement of suitability, and the improvement of estimate precision. There are two developing trends of USLE, one is traditional way, which enhances the prediction ability of USLE through introducing new applicable parameters or optimizing parameter values without modifying model structure. The other is nontraditional way, which makes more flexible and reasonable confirmation of factors as well as more valuable and ascertainable result of soil loss quantities by using fuzzy logic or artificial neural networks to modify USLE structure.
  • ARTICLES
    Discussion on Classification and Coding of Environment Background Data and Their Application
    LIU Jinsong, CHEN Hui, GAO Jixi
    2004, 6(4): 56-61.
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    Classification and coding of environment background data is studied in this paper and the main conclusions are as follows: Environment background data is the object of study, based on the integrated research of attribute characteristics of geographic base, semantic time, storage format, record medium, responsible institution and thematic information, the integrated concept of environment background data is put forward. In the Land System Science supported by Geoinformatics, the classification and coding of environment background data should emphasize discovering environment background data from macroscopic view and the classification and coding of environment background data means "integration is soul, classification is for application". In the course of implementation of geographical data-metadata, metadata should be the criterion carrier of classification and coding. Before the uniform classification and coding is ascertained, the
  • ARTICLES
    Study on Web-oriented Geo-data Sharing Platform System Structure
    WANG Juanle, YOU Songcai, XIE Chuanjie, ZHU Yunqiang
    2004, 6(4): 62-65.
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    It is difficult to realize the Web-oriented geo-data sharing, because geoscience features a wide range of more than a dozen specialized areas. This paper studies the principal structure of geo-data sharing network platform taking into consideration of these features.Designed geo-data sharing platform is composed of 5 parts, which includes website portal, data sharing business tier, core service tier, data sources management tier and network foundation. Thirteen function modules are organized in this architecture efficiently.The development of metadata theories and their application techniques provide a solution to mass data sharing in web. In this platform, metadata management and services modules (MMS) serve as the infrastructure. They are designed and built based on RDF/XML models recommended by W3C. The foundation′s hierarchy includes 3 tiers, i.e., application tier, RDF/XML resource management tier, and data resources tier. RDF/XML, served as a middle tier, plays an important role in MMS. As a typical data of geoscience, geospatial data can be published via this platform. Its prototype is researched and developed by means of 7 selected metadata ports and WebGIS technologies.The running environment of Web-oriented geo-data sharing platform is built up with support of Web server and several application servers. Research and experiment showed that Apache + Tomcat + ArcIMS server can work well in the system structure′s physical deployment.
  • ARTICLES
    Geo-association Rule with Spatiotemporal Reasoning
    SU Fenzhen, DU Yunyan, YANG Xiaomei,LIU Baoyin
    2004, 6(4): 66-70.
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    Mining the association rule from the database appeared the first in the commercial field. In the mid 1990’s, the geo-association rule was promoted. Geo-association means that the spatiotemporal relationship between the geographic events, which can be used to reasoning one spatiotemporal geographic event or event combination from another event or event combination. Based on the review for the research background and development of geo-association rule, the geo-association rule can be categorized by its complexity as spatial characteristic rule, spatial discriminate rule, spatial association rule and spatiotemporal association rule. With the definition of spatiotemporal rule by mathematic language, the effect of the different indices on the rule mining is analyzed. Furthermore, the presentation analyses the data processed in the rule mining with the level of generalization, the data dimension, the variable type and spatial topologic relationship respectively. The geo-association rule can be categorized as single level rule or inter-level rule by the level of generalization, as one-dimension or multi-dimension rule by data dimension, as boolean or numeric rule by the variable type, as local or focal rule by the topologic relationship. Finally, the presentation describes the flow to forecast the fishing ground using the geo-association rule.
  • ARTICLES
    Population and Socioeconomic Data Information System and Its Application
    LUO Chun, YANG Xiaohuan, JIANG Dong
    2004, 6(4): 71-75.
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    At present, there exists plenty of population and socioeconomic data in the resource and environment area . Pixelizing and analyzing the population and socioeconomic data are necessary for researches on the interactions between human and nature. Based on the technical process on the pixelizing of population and socioeconomic data applied by the Resources and Environmental Data Center, Institute of Geographic Sciences and Natural Resources Research, CAS, this paper puts forward the spatial population and socioeconomic data information system. With the knowledge on systems engineering, it analyses the system requirements, the data flow, the needful technique and the aim. The compositive system is achieved with Visual Studio.NET and based on ArcObjects. The goal of the system is to set up the 1×1 km2 gridded population and socioeconomic dataset and to benefit dataset updating and expansion.
  • ARTICLES
    On the Application and Service Strategies of Fundamental Geographic Information——A Case Study of Hunan Province
    QIN Jianxin, XIANG Hongpu, CHEN Junyao
    2004, 6(4): 76-79.
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    Fundamental Geographic Information is the framework and carrier of geo-spatial information and other information in information era, and is the important information fountain of scientific decision-making in the national sustainable development and the government's information and network construction. Based on the construction of fundamental geographic information in Hunan province, the paper analyzed the application of fundamental geographic information, and pointed out the main problems among the construction of fundamental geographic information:(1) the role of fundamental geographic information is not lay store by fully recognized by department concerned,, (2) the investment in the construction of fundamental geographic information is low, and (3) the skilled and technical personnel engaging in GIS industry is lack. It then put forward the service strategies and share mechanism in fundamental geographic information construction, and finally rendered the main projects among the construction of fundamental geographic information in Hunan province.
  • ARTICLES
    Analysis and Discussion on Spatial Data Engine Technologies
    ZHANG Mingbo, SHEN Paiwei, LU Feng, CHENG Changxiu
    2004, 6(4): 80-84.
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    Integrated storing and accessing geographical features related information is one of the most important technologies for GIS application developments. It has been a consensus of opinion in the GIS society that storing and managing mass spatial data with current business relational database management systems under the support of extended relational models is an efficient and effective technology for developing mass data and network oriented spatial database management systems. In this paper, the authors analyzed and discussed some typical spatial database management platforms including ArcSDE, Oracle Spatial, Informix Spatial DataBlade, DB2 Spatial Extender and MySQL Spatial Extensions from the view of storing models, process management schema, spatial querying and indexing, and data cache approaches. It is argued that current business spatial data engines or extension technologies still deserve much more research and improvements, especially for topology representation within relational database management systems and application schema, adaptive spatial indexing and optimization methods, and user defined complex object representation, sharing and inter-operability.
  • ARTICLES
    Vectorization of Raster Data and Solution to Relevant Problems
    FU Qinghua, NI Shaoxiang, GUO Jian, LI Kaili
    2004, 6(4): 85-89.
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    Raster and vector are two major types of data format in GIS, especially at presenst, remote sensing images have been very important data resource of GIS. With the development of GIS, remote sensing data will play an even greater role in GIS. But however, remote sensing data is usually raster data, and cannot meet the requirements of spatial analysis in GIS, so a conversion of raster data into vector one is of great importance for GIS. Although there are many algorithms and softwares for vectorization of raster data, yet some problems still exist in the process of vectorizing raster data, for example, the vector images thus produced have some islands and self-intersect polygons, or there are only polylines without good topological relation. Hence this can hardly gratify the need of our work.On the basis of summarizing the existing algorithms and following the topological theory, an improved method for converting raster data to vector one is suggested in this paper. In other words, firstly it's determined by the relation of similarities or differences between four neighboring pixels(Fig.2) whether the crosses of neighboring pixels(Fig.1) belong to nodes or coordinate points, then in the process of searching nodes and coordinate points, both vertical and horizontal line segments are picked up at the same time in order to realize the vectorization of raster data more quickly and more efficiently. In addition, by use of the methods such as automatically breaking and widening grid size, some common problems in the course of vectorization of raster data such as self-intersected polygon and island are successfully solved. The authors programme a programme in Visual C++ to realize the algorithm in this paper, and contrast its result with other softerwares or algorithms. The algorithm has some better virtues:1)it is easy and convenient to practice; and 2) it has perfect topological relation. Therefore, the improved method is of great benefit to retrieve useful information from remote sensing images, and to promote the integration of Remote Sensing and Geography Information System.
  • ARTICLES
    Displaying of 3D Topography with Real Dynamic and Mutual Method
    YANG Huachao, LUO Deli
    2004, 6(4): 90-92.
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    It is well known that the topography is the most complicated object in nature. With the development of GIS technology, the 3D rendering of topography is becoming one of the most important research areas today because the 3D digital topography is a very important part of GIS. At the same time, 3D digital topography is also a key technology of VR(Virtual Reality). However, it is a difficult task to bring this key technology into effect because large quantities of data have to be coped with. These data mainly include data of topography and data of topographic surface features. There is no doubt that creating a real-time, interactive, vivid topographic environment using these spatial geographic data in computer is a very complicated work. Fortunately, with the development of computer technology, we can easily draw it in common computer with OpenGL. In this paper, we briefly discussed the technology of drawing 3D graphics and the solid view of digital topography as well as the mechanism and procedure of real displaying of 3D topography. Using this technology, we can easily render a 3D digital topography in a common computer. We also discussed two methods of realizing the dynamic view of topography, one is the viewpoint fixing with object-point moving. In fact, in many cases, in order to better understand the topography, we need to observe the 3D digital model along a selected routing. So we can use another method of dynamic view, that is object-point fixing with viewpoint moving. A specific example of drawing the 3D digital topography using the previously method is given.
  • ARTICLES
    Study on Spatial Knowledge Querying Methods Based on Ontology
    WANG Jinggui, SU Fenzhen, DU Yunyan, YANG Xiaomei, CHEN Xiufa
    2004, 6(4): 93-99.
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    Spatial information querying methods in traditional GIS have many limitations, their operation is complicated, the presentation of querying results is highly formalized, and their user interfaces are so complex that they are not suitable for most people and decision makers. An Ontology is a formal, explicit specification of a shared conceptualization, as a tool for conceptual modeling which can describe information system on semantic and knowledge level, it is quite suitable for information retrieving on semantic and knowledge level. In this paper, we developed a new spatial information query method, named ODSKQ, which means Ontology-Driven Spatial Knowledge Query. The ODSKQ method is built directly for users who have not special knowledge on GIS, and because it uses natural language to describe querying conditions. The result of querying is highly synthetical and knowledgeable, providing users direct answers while hiding the complicated calculation and reasoning processes, it is indeed a highly humanized, intelligent spatial querying method. In the end of this paper, we took spatial query of resources and environment domain in coastal zone as an example to verify the possibility and usefulness of ODSKQ, and the results showed that the ODSKQ method is very useful and powerful in the process of solving spatial problems.
  • ARTICLES
    Implementation of Wireless Location Services and Its GIS Server Based on XML
    CHEN Zuan, WAN Qing, WU Jie
    2004, 6(4): 100-104.
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    WLS(Wireless Location Services) will eventually influence the spatial information management market, and it will be one of the most important increment services in the next generation of mobile networks. GIS and spatial database will play a key role in this field. This paper introduces the implementation of wireless location services and its GIS server based on XML technology, including the system architecture, application scheme and the organization of the WLS spatial database. We provide an almost complete procedure of wireless location services based on our application scheme, which is described with example XML code stream via extended HTTP protocol, also called SOAP. According to practical urban LBS application and wireless communication cell's overall arrangement, we compared two spatial database storage models and draw a conclusion that the flavor of LBS data must be organized by spatial database and independent city style, not by communication cell style. An instance of such a GIS server about wireless location services on UNIX platform is provided at the end of this paper. This type of GIS server can be deployed at the background of GSM, GPRS, WCDMA, CDMA, etc. And it has been completely tested and will be launched into deployment soon.
  • ARTICLES
    Spatial Database Design and Realization Based on Geodatabase
    LUO Zhiyong, LIU Xiangnan
    2004, 6(4): 105-109.
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    In recent years, how to use spatial database to store and manage spatial data has become a hot topic in the field of GIS. However, the study on spatial database structure design has been ignored relatively. Most investigations just emphasize the realization of special application of softwares which are relative to spatial database. Accordingly the author carried out a comprehensive and in depth discussion about the related questions in this article, including the difference between spatial database and general database, the key technology and frequently asked questions while building spatial database. In this article many important thoughts and rules for the different design stages are put forward and the importance of standardized design is also emphasized. In the structure realization stage, a detailed treatise about how to scheme out a perfect Geodatabase with CASE tools has been given. The facts proved the importance of UML and CASE tools in the design of spatial database.
  • ARTICLES
    An ORDBMS Based GIS Data Management Model and Its Realization
    ZHANG Maozhen, SONG Tieying, TANG Xiaoming, LIU Pengju
    2004, 6(4): 110-116.
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    Efficient spatial data management is a key issue of GIS technology. Object-relational database, because of its advantage in data sharing, security and transferring in network, is recognized as an effective tool for GIS data management, and many studies on this area have shown great success. But in actual application with large quantity of data, some difficulties still exist. This paper, based on the analysis of the features of Raster and vector data and the applicability of Object-Relational database to the management of GIS data, presented a practical integration model for the two types of data in GIS. This integrated spatial data model was applied to the GIS software-ViewGIS, which was successfully used in building the provincial forestry GIS of Hunan province in 2003.The ORDBMS based GIS spatial data model, which uses Oracle Spatial mechanism for vector data and RDB LOB mechanism for raster data respectively, realized the goal of managing raster and vector data in the same database. This can not only greatly benefit end users with remote data access, data manipulation and other mechanisms of the database, but also avoid the barrier of unopened data structure in ArcSDE and has higher efficiency.
  • ARTICLES
    Research of Design Pattern on Visualization of Feature Model
    LIU Bilong, ZHAO Chunjiang, WU Huarui
    2004, 6(4): 117-120.
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    As the realization of Geographical Information System (GIS) is a quite complicated course, the method of modeling and hierarchical structure is used widely. Furthermore, the applied design pattern makes it easier and more convenient to use successful designs and software architecture repeatedly than ever before, which benefits the development and reconstruction of GIS. The thesis, through the analysis of geometry model architecture of Geographical Information System feature model, fully uses and combines various kinds of design patterns to probe into the combination of composite pattern and visitor pattern together for feature organization, and makes it possible to access inhomogeneous geometry in geometry collects. Generally speaking, composite pattern and strategy pattern on rendering geometry for feature visualization enable us to separate rendering from feature naturally and sustain various kinds of rendering during the development and implementation of visualization of geographic feature. Advantages of this kind of structure lie in not only satisfying easily Open GIS abstract specification and implementing specification of simple geometry, but also keeping structure clearly and module democratized, and making the structure more flexible and natural. It is beneficial to the development, maintenance and expansion of the Geographical Information System.
  • ARTICLES
    Design and Realization of Web-shared Map-Symbol-Base in Server-end Based on GIS Component
    LU Yimin, CHI Tianhe, CHEN Chongcheng, ZHANG Xin
    2004, 6(4): 121-126.
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    Web-shared digital map-symbol-base is an important research direction associated with sharing spatial information on the internet and interactive analyzing service. In this paper, we illustrate how the shared digital map-symbol-base was integrated into the Fujian province e-government information sharing platform service agent system, and analyze the present technique about designing and developing of shared digital map-symbol-base based on GIS component.A design principle on digital map-symbol-base faced network service application has been presented. By using GIS component ArcObject (ArcObject is built using Microsoft′s Component Object Model (COM) technology), the prototype of shared digital map-symbol-base has been established and its functions of symbol editing, storing and managing as well as its symbolizing process have been explored in detail. By integrating into the Fujian province e-government information sharing platform service agent system, the shared digital map-symbol-base can primarily meet the application demand on sharing spatial information based on the Internet and interactive analysis service in different departments and different realms of profession.