UNIT 46 - MANAGING ERROR

UNIT 46 - MANAGING ERROR

  • A. ERROR PROPAGATION
  • B. ARTIFACTS OF ERROR
  • C. STORING ACCURACY INFORMATION
  • REFERENCES
  • EXAM AND DISCUSSION QUESTIONS
  • NOTES

    UNIT 46 - MANAGING ERROR

    A. ERROR PROPAGATION

    Example application

    Error analysis

    Sensitivity analysis

    B. ARTIFACTS OF ERROR

    Raster data

    Vector data

    Digitizing artifacts

    Strategies used to avoid problems:

    Polygon overlay artifacts

    C. STORING ACCURACY INFORMATION

    Raster data

    Vector data

    Positional uncertainty

    Attribute uncertainty

    REFERENCES

    Burrough, P.A., 1986. Principles of Geographical Information Systems for Land Resources Assessment. Clarendon, Oxford. Chapter 6 on error in GIS.

    Chrisman, N.R., 1983. "The role of quality information in the long-term functioning of a geographic information system," Cartographica 21:79.

    Goodchild, M.F. and S. Gopal, editors, 1989. The Accuracy of Spatial Databases, Taylor and Francis, Basingstoke, UK. Edited papers from a conference on error in spatial databases.

    EXAM AND DISCUSSION QUESTIONS

    1. Define the difference between sensitivity to error in principle and in practice.

    2. Imagine that you represent a community trying to fight the proposed route of the powerline discussed in this unit. What arguments would you use to attack the power utility company's methods?

    3. Compare the methods available in any digitizing system to which you have access, to those discussed in this unit. Does your system offer any significant advantages?

    4. Some GIS processes can be very sensitive to small errors in data. Give examples of such processes, and discuss ways in which the effects of errors can be managed.


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