Dissertation Defense Details
Discrete Global Grid Systems: A New Class of Geospatial Data Structures
| Author: | Kevin Sahr |
|---|---|
| Date: | June 29, 2005 |
| Time: | 09:00 |
| Location: | 220 Deschutes |
| Committee: | John Conery (Chair) Andrzej Proskurowski Arthur Farley Patrick Bartlein |
Abstract
Limitations in traditional approaches to the representation of geo- referenced data sets has led to the development of a number of data structures based on regular, multi-resolution partitions of spherical polyhedra. These constitute a new class of geospatial data structures that we call Discrete Global Grid Systems (DGGSs). We survey the proposed DGGS approaches and show that the primary DGGS alternatives can be constructed by specifying five substantially independent design choices, of which the hierarchical spatial partitioning method has the most impact on the development of efficient data structures.
We then develop a topology-independent implementation of DGGSs that will enable us to perform empirical comparisons between the primary DGGS topologies of hexagons, triangles, and diamonds. For our initial comparison we implement a simple dynamic simulation by extending the definition of a planar cellular automata to be spherical, multi- scale, and topology-independent; we report the first results for a study of such simulations.
Finally, we note that the practical use of icosahedral aperture 3 DGGSs has been hindered by a lack of efficient hierarchical location coding schemes. We introduce two path-based hierarchical location coding systems: the Icosahedral Modified Generalized Balanced Ternary approach for indexing point data, and the Icosahedral Aperture 3 Hexagon Tree for indexing raster data and for use in bucket-based spatial databases. Algorithms for conversion from geographic coordinates to these systems are given.