UNIT 13 - THE VECTOR OR OBJECT GIS

UNIT 13 - THE VECTOR OR OBJECT GIS

Compiled with assistance from Holly Dickinson, State University of New York at Buffalo


For Information that Supplements the Contents of this Unit:

Organizing Attribute Data (Foote and Huebner/Geographer's Craft) -- Flat files and spreadsheets, hierarchical files, relational files.
Representation and Data Quality (Chrisman/U of Washington) -- Primitives for representation: attribute, space, points located in a coordinate system, lines formed from line segments; understanding Topology; alternative definitions of data quality.
Example of Topological Relationships (Foote and Huebner/Geographer's Craft) -- Nodes, arcs, polygons, contiguity.
Vector Data Maintenance and Analysis -- Introduction; vector data analysis (graphics); overlay operations; neighborhood operations; connectivity functions.
Vector View of the World (Foote and Huebner/Geographer's Craft) -- Plus, graphical comparisons between raster and vector systems.


  • A. INTRODUCTION
  • B. "ARCS"
  • C. DATABASE CREATION
  • D. ADDING ATTRIBUTES
  • E. EXAMPLE ANALYSIS USING VECTOR GIS
  • REFERENCES
  • EXAM AND DISCUSSION QUESTIONS
  • NOTES

    This unit begins a two part introduction to vector GIS. We have placed these units here since we feel this discussion benefits from an understanding of the previous introduction to spatial data concepts in Units 10 to 12. However, with a little revision, it is possible to move this module so that it follows Units 4 and 5 on raster GIS.

    UNIT 13 - THE VECTOR OR OBJECT GIS

    Compiled with assistance from Holly Dickinson, State University of New York at Buffalo

    A. INTRODUCTION

    Vector data model

    B. "ARCS"

    Storing areas

    C. DATABASE CREATION

    Building topology

    Editing

    Relationship between digitizing and editing

    Edgematching

    D. ADDING ATTRIBUTES

    E. EXAMPLE ANALYSIS USING VECTOR GIS

    Objective

    Procedure

    Result

    REFERENCES

    Beard, M.V. and N.R. Chrisman, 1988. "Zipping: a locational approach to edgematching," The American Cartographer 15:163-72. Describes a solution to the edgematching problem.

    Chrisman, N.R., 1990. "Deficiencies of sheets and tiles: building sheetless databases," International Journal of Geographical Information Systems 4:157-67. A more general discussion of building edgematched databases.

    ESRI, 1990. Understanding GIS: The ARC/INFO Way, ESRI, Redlands, CA. A general introductory tutorial for ARC/INFO, a well-known contemporary GIS.

    Tomlinson, R.F., H.W. Calkins and D.F. Marble, 1976. Computer Handling of Geographical Data. UNESCO Press, Paris. Excellent semi-technical description of CGIS, an early vector-based system.

    EXAM AND DISCUSSION QUESTIONS

    1. List and describe the processes involved in constructing a vector database by digitizing maps.

    2. By using simple sketches, describe and illustrate typical problem cases which lead to difficulties in building area- object topology in a vector database, and the strategies which various GISs use to minimize editing effort.

    3. Discuss the applications of GIS, in relation to the vector data model. Give examples of cases where the model

    would be particularly inappropriate in comparison with raster.

    4. Why did the designers of CGIS choose a vector data model, and yet use scanning as the major method of input?


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