Copyright: S. Shekhar, C. S. Dept.,
University of Minnesota, Minneapolis, MN 55455. ,,.(home)S2: Chapter Outline
2.1 Models of Spatial Information
2.2 Three step Database Design
2.3 Extending ER with spatial concepts
2.4 OO Data Modeling with UML
Copyright: S. Shekhar, C. S. Dept.,
University of Minnesota, Minneapolis, MN 55455. ,,.(home)S3: %Models of Spatial Information
%Why is spatial special?
Continuous domains (e.g. space)
complex objects (e.g. polygons)
Field vs. Object based models
Fig. 2.1 (pp. 54)
Modeling a continuous phenomenon
Field functions (Fig. 2.1(b))
Set of polygon objects (Fig. 2.1(c))
Copyright: S. Shekhar, C. S. Dept.,
University of Minnesota, Minneapolis, MN 55455. ,,.(home)S4: %Key Concepts - Field Model
Components:
Spatial framework: (a partitioning of space)
field functions : framework -- > attribute domain
field function operators
Operations on spatial objects
Local(f,g): f+g, f-g, f or g, ...
Focal(f) : derivative(f)
Ex. drainage direction (gradient) from elevation
Zonal(f,z): aggegate f values group by z values
Ex. average elevation of each state in USA
Closure under operations
Copyright: S. Shekhar, C. S. Dept.,
University of Minnesota, Minneapolis, MN 55455. ,,.(home)S5: %Key Concepts - Object Model
Components:
Classes of Spatial objects
Spatial operators
Classes of spatial objects
points, point collections
polygons, polygon collections
linestrings, linestring collections
Closure under operations
Operations on spatial objects
Set oriented
Topological - see Table 2.1 (pp. 49)
... nine intersection model
Metric
Euclidean
Copyright: S. Shekhar, C. S. Dept.,
University of Minnesota, Minneapolis, MN 55455. ,,.(home)S6: %Comparison with Relational Model
Conceptual Model
Entity Relationship, or UML
Spatial relationship - crowd the diagram
Pictograms to simplify the diagrams
Make spatial relationships implict
Example
Figure 2.3 (pp. 59)
Figure 2.6 (pp. 68)
Pictogram specification (sec. 2.3.1, pp 65)
Q? Do pictogram simplify logical level schema too?
Figure 2.4 (pp. 63)
Copyright: S. Shekhar, C. S. Dept.,
University of Minnesota, Minneapolis, MN 55455. ,,.(home)S7: %Comparison with Relational Model
Logical- Relational, OO, Object Relational
User defined data types
User defined functions
Spatial data types can be incorporated
Simplifies logical schema
... Removes FKs, tables for spatial relationships
Physical- relations, indexes
Storage of large spatial objects
Spatial indexes (e.g. R-tree)
Copyright: S. Shekhar, C. S. Dept.,
University of Minnesota, Minneapolis, MN 55455. ,,.(home)S8: %Exercises
Ex. 5 (pp. 73)
Copyright: S. Shekhar, C. S. Dept.,
University of Minnesota, Minneapolis, MN 55455. ,,.(home)
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