UNIT 36 - HIERARCHICAL DATA STRUCTURES

UNIT 36 - HIERARCHICAL DATA STRUCTURES

  • A. INTRODUCTION
  • B. INDEXING PIXELS
  • C. THE QUADTREE
  • D. VARIANTS OF QUADTREES
  • E. ADVANTAGES OF HIERARCHICAL DATA STRUCTURES
  • REFERENCES
  • DISCUSSION AND EXAM QUESTIONS
  • NOTES

    UNIT 36 - HIERARCHICAL DATA STRUCTURES

    A. INTRODUCTION

    B. INDEXING PIXELS

    Procedure

    Decoding locations

    C. THE QUADTREE

    Coding quadtrees

    Accessing data through a quadtree

    Comparison of different data structures

    D. VARIANTS OF QUADTREES

    E. ADVANTAGES OF HIERARCHICAL DATA STRUCTURES

    REFERENCES

    Gargantini, I., 1982. "An effective way to represent Quadtrees," Communications of the ACM 25:905-910.

    Mark, D.M., J.P. Lauzon and J.A. Cebrian, 1989. "A review of quad-tree based strategies for interfacing coverage data with digital models in grid form," International Journal of Geographical Information Systems 3(1):3-14.

    Samet, Hanan, 1984. "The quadtree and related hierarchical data structures," ACM Computer Surveys 16(2):187-260.

    Samet, Hanan, 1989. The Design and Analysis of Spatial Data Structures. Addison-Wesley, Reading, MA. Contains an excellent review of quadtrees.

    Samet, Hanan, 1989. Applications of Spatial Data Structures. Addison-Wesley, Reading, MA. Contains an extensive review of applications of quadtrees.

    Shaffer, C.A., H. Samet and R.C. Nelson, 1990. "QUILT: a geographic information system based on quadtrees," International Journal of Geographical Information Systems 4(2):103-32.

    Waugh, Thomas C., 1986. "A response to recent papers and articles on the use of quadtrees for geographic information systems," Proceedings, Second IGU Symposium, Seattle, pp. 33-37. An interesting critique of quadtrees.

    DISCUSSION AND EXAM QUESTIONS

    1. "Hierarchical data structures are one of the few genuinely new concepts to come out of GIS research". Discuss.

    2. Discuss the arguments presented for and against quadtrees in Waugh, 1986.

    3 Summarize the arguments for and against the octahedral decomposition of the globe presented in the unit, as a means of representing and analyzing global databases.

    4. Modify the quadtree concept so that it is suitable as a method of storing digital elevation data. What are the advantages and disadvantages of this approach over a simple raster?

    5. What would be the advantages and disadvantages of using Dutton's global tesselation as the primary means of discrete georeferencing, rather than street address?

    6. Three-dimensional spatial databases are of great interest in geology, geophysics, subsurface hydrology, atmospheric science, oceanography and the mining and oil and gas industries. With reference to one or more of these, discuss the suitability of the octtree as a data model.


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    Last Updated: August 30, 1997.