1. Geographic Information Systems
GIS Data Databases

2. 1 GIS Databases
A database is a shared collection of data with secure controlled access
Data are stored independently of their applications
A GIS database contains geographic data
A database management system (DBMS) is a collection of software programs that facilitates the efficient and effective storage and access of data
A GIS DBMS

3. 2 Levels of Data Abstraction
Conceptual data model
- user's perception of the real world
Logical data model
- a formal description of the data model
   
Physical data model
- physical storage of the data (e.g., format, order, path)

4. 2 Levels of Data Abstraction …
Human-oriented
Reality
Conceptual Model
Increasing
abstraction
Logical Model
Computer-oriented
Physical Model

5. 3 Database Functions Records, fields, and keys - a row is a record
- a column is a field
   

6. 3 Database Functions …
Map librarian and tiles

7. 3 Database Functions … Adding, updating and deleting records
Extracting information from data
Maintaining data security and integrity
Supporting applications

8. 4 Database Data Models (Logical Models)
Hierarchical data model
Network data model
Relational data model
Object-oriented data model

9. 4 (3) Relational Data Model
The database consists of several tables
A row is a record and a column is a field 
   

10. 4 (3) Characteristics Every field can be used as a key in a search
A cross file search can be done by join, as long as at least one field is common to both files
A link table can be created with needed attributes, without taking actual storage space

12. 4 (3) Advantages and Disadv
- Flexible, no structure restrictions for search
- Easy to understand
- Less data redundancy
Disadvantages
- There ay be 1:M or N:M relationships between tables

13. 4 (4) Object-Oriented Data Model
Encapsulation
Objects, attributes, processes
Inheritance
Association and aggregation

14. 4 (4) Object-Oriented Data Model..
Encapsulation
- Data (attributes) and functions (processes) are combined in one object

15. 4 (4) Object-Oriented Data Model..
Inheritance
- Data and functions are organized in a hierarchy
- Objects inherit characteristics and functions of their ancestor objects
Animals
A head and a body, feed
Mammals
Four legs, sit
Fish
Fins, swim

16. 4 (4) Object-Oriented Data Model..
Association and aggregation
a member of vs. a part of
Fish
location:
time:
weight:
Aquatic System
predator weight:
prey biomass:
temperature:
Habitat
inhabitant
habitat
Inhabitation

17. 4 (4) Advantages and Disadv
- Easy for modeling and the representation is close to human perception
- Reduce the complexity of software development
Disadvantages
- Most existing object-based systems are a hybrid of relational and object-based databases

18. 4 (4) Object-Relational Databases
Use an enriched set of graphic element types on top of the three basic types of points, lines, and polygons

19. Object-Relational Databases..
two levels of geometries: features geometry, and components of features geometry
features geometry
components

20. Readings
Chapter 3

21. Object-Relational Databases..

22. Levels of Data Abstraction …
Conceptual Model
Objects and relationships
Real World
Logical Model
Diagrams
And lists
Physical Model
Database
Schema

23. Spatial Types – DB2 Spatial Extender Oracle Spatial
ArcSDE/ArcGIS Server