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Geo-union: A coherent Geo Information System with environment analysis and planning

Li Qinmin, Hsu Chochun, Chen Jiong
Dept. of Computer Science, Peking University, China

Zhou Xintie
National Remote Sensing Centre of China, Beijing

Zhang Zhiyong
Institute of Geography , Academy of Sinica


Abstract
A coherent geographical information system Geo-union has been implemented on microcomputers and put into practical use with many Remote Sensing projects. In this paper, major functions and characteristics of the system are presented, and a typical application system for environmental study of dynamical analysis and planning of geo-resources is discussed in terms of using Geo-union as a basis of application tool-set.

Introduction
The geographical information system (GIS) in conjunction with remote sensing study has become increasingly important. On the basis of GIS, result data from remote sensing study not only can be stored and queried, but also be further processed and analysed by using dynamical analysis and planning models. These are the major goals of our efforts to develop a geo information system GEO-UNION which has been implemented on microcomputers and been put into practical use with many remote sensing projects. In following sections main characteristics of the system GEO-UNION, and its major functions will be presented. A typical application of environmental study on dynamical analysis and planning in terms of geo-resources management will be shown to exemplify the capacity of the system that it can further be used as an software development tool-set for professional application development users[1]

The Geo-union system
  1. The system environment
    Hardware : 286or 386 with EGA high resolution graphic display Kurta Digitizer, and Rolland Plotter
    Software : Dos 3.0, and ORACLE 5.0 RDBMS

  2. Six functional modules of the system (Fig.1]


    Fig.1 the modules of GEO-UNION


  3. The spatial data management module (SDMM)
    This module is responsible for managing and processing data in vector form. It was five submodules:

    1. Map Directory. Every map is registered in the system map-directory, including its name, geographical subject, map-size, and other features of the map. The submodule also contains tables of attribute codes, each of which is considered to be a possible attribute value attached to a spatial entity such as a polygon, a line or a point.

    2. Map Inputing. Interactively map inputing through digitizer or converting maps from remote sensing data (in raster form) into vector structures.

    3. Map Editing . Various functions are provided for modifying the detail of geometrical positions and spatial relations between spatial entities within a map, In addition, and attribute code can be entered by keyboard and attached to each spatial entity.

    4. Map Operating. Operations on maps such as map overlapping, map clipping, map joining, polygon selection, and polygon merging are available to create new maps by operating on existing maps.

    5. Map drawing. User can interactively indicate many features with a drawing such as definition of a map legend by using a library of legend symbols (Fig.2) the drawing size, map name, the relative position of map areas for showing the map name and the legend. Functions for annotation in both English and Chinese are also provided.

  4. Main characteristics of the system
    In addition to the basic functions which every GIS system owns, GEO-UNION system can be characterized by several main features.

    1. Procedures for map formation
      There are five ways of extracting data to form new maps in vector structure:
      (a) Converting data from image processing (b) Processing data from plan comp equipments (c) Extracting data by using DTM module [2] (d) Ordinary digitization . (e) Extracting data by data analysis. For example, soil erosion maps can be formed by an application module of soil evaluation.

    2. Coherent handling of maps represented in two kinds of data structures (in vector form or in raster form) . GEO-UNION system maintains each map in one of the two representation forms according to its data source and its usage. (Fig.3) In order to facilitate the conversion of a map from one representation into another parameters such as the number of grids(rows and columns) in one map can interactively be defined.

    3. Working with Relational data base system ORACLE We have developed an interactive query system Geo-Query based on the connection between the spatial information mangement and RDBMS (ORACLE)[3]

  5. System supports for two-level users
    In summary, GEO-UNION system is intended to be used by users of two levels.

    1. The end users who are managerial persons from various departments such as managers from agriculture or foretry planning departments, can interact with GEO-UNION through a user-friendly man-machine interface which supports a whole set of map operations queries with spatial relations and attribute specifications, and map drawings (Fig.4)

    2. The application programmers who are responsible for developing an application system with a large amount of map data, can get the support of GEO-UNION by invoking subroutines from a library in GEO-UNION which greatly ease the efforts of the application program development.

Fig.2 Legend defining


Fig.3 Two data structure in GEO-UNION


Fig.3 User-interface of GEO-UNION


The development of an application system for dynamic analysis and spatial planning
An application system for the analysis and planning of environmental resources in PINGQUAN county has been developed by the support of GEO-UNION and DYNAMO software. The efforts can be summarized in the following.

  1. The Data flow Diagram of the application system (Fig.5)


    Fig.5 The data flow for analysis of system dynamics


  2. Building a library of subject maps

    • Maps by digitization , e.g. the maps of soil sructure, and rainfall distribution.
    • Maps by processing data with DTM e.g. the slope map of the terrain
    • Maps obtained by specific analysis programs [4] (Fig. 6)



    Fig.6 Diagram of the formation of soil erosion map and land evaluation map


  3. Dynamical Analysis by historical data from maps in different periods of time

    The changes of forest distribution in PINGQUAN county have been figured out by overlaying maps in different periods of time, selecting areas where the change of forest type has occurred, and collecting dynamical data with other reference maps.

  4. Building a model for the analysis of the environmental dynamics

    The model is intended to
    • predict the behavior of soil erosion.
    • analyze the bearing capacity of land
    • produce plans in terms of a set of subject variables for a coordinated economical development in years ahead.

    The analysis has been carried out by the both supports fromthe spatial data management in GEO-UNION and the simulation capacity in DYNAMO. The results of the analysis are transferred to the spatial planning as the next stage of planning.

  5. Spatial Planning

    The objective of spatial planning is to use the results of variables in the above mentioned simulation as a set of goals and to try to distribute the variables into different geographical areas in such a way that a set of environmental constraints always maintain valid. The data flow diagram of the spatial planning module is shown in Fig.7


    Fig.7 Data flow for spatial planning


    A specific form of rule has been implemented and used as the representation for each environment constraint:

    Rule: IF (m1<= Atl(R) < = M1) (mJ2 <=A t2(R) < = M2)....and (mJp <= Atp(R) <=Mp)

    Then X is suitable for the concerned area R.

    Where each Ati(R) (i=1,2...., P) is the attribute value of the concerned area R on a given map, mi and Mi (i= 1,2 ,...p) are the bound constants for attribute Ati X is one of the goal variables of the spatial planning.

    The spatial planning module uses the set of constraints as a rule-base, and searches every area (e.g. grid) in a given map to see if one of constraints is met.

    In order to improve the effectiveness and efficiency of spatial planning, four issues have been considered:

    • A user-friendly interface for the planning experts to update and browsing the rule base, has been implemented.
    • A rough planning which uses a set of relatively large polygons (in vector structure) as the search space can precede the detail planning with raster scanning, to improve the time-consuming of search.
    • A list weights is attached to the set of planning variables to resolve possible conflicts between them. The results of spatial planning is shown in reference[5]
Conclusions
The geo-information system GEO-UNION on microcomputer provides a spectrum of approaches capable of dealing with tasks involved in a large amount of information concerning the structures of two dimensional entities and its attributes.

Various kinds of application systems can also be developed based on the support of GEO-UNION . Especially, many kinds of ecological and economical models can be incorporated with GEO-UNION to deal with the huge amount of data available for evaluations. It is desirable to consider possibilities and approaches which can integrate a model base with GEO-UNION and make it easier for planning users to obtain relevant picture for broad viewing and predicting.

References
  • Xu Guanhua, Xu Jiyan: The Research collected works in Regenerating Resource's Remote senses, Science Press 1988 , PP262-279.
  • Digital Terrian Models: An overview, Photogrammetic Engineering and Remote Sensing, No12, 1978.
  • Zhong Zhenxiang, et al.: GEO-UNION : A geo-object Oriented Query System Integrated with ORACLE for GIS, In this proceedings.
  • Wang Xianwu: The Applications of General Equation for soil and water Loss in Chengde prefecture, Edited by search Institute of soil conservation of Chengde.
  • Zhang Zhiyong, et al.: The combination of Dynamic simulation with GIS for Evaluation and Predition of Ecological Benefit of Shelter Forest, In this proceedings.