GLS613 Creating and Maintaining Geographic Databases
What you have/suppose to learn so far? • Data model: How we want to represent geographic data in a computer • Vector, raster, TIN, network etc.
• Data sources: What types of geographic data can be used in GIS
• Geographic Database: How we want to store geographic data into a computer
Geographic data model
Data collection
Geographic database
Geospatial database
Traditionally…
Definitions • A database can be thought of as an integrated set of data on a particular subject • Geographic databases are simply databases containing geographic data for a particular area and subject
• Describes how to create and maintain geographic databases, and the concepts, tools, and techniques that are available to manage geographic data in databases.
• Files
• traditional approach of storing data • Database
• an integrated set of attributes on a particular subject • Geographic (=geospatial) database
• set of attributes on a particular subject for a particular geographic area
• Database Management System (DBMS)
• software to create, maintain and access databases
Geographic Information Systems • We can describe any
element of our world in two ways:
Location Information: Where is it?
Attribute Information: What is it? Species: Oak Height: 15m Age: 75 Yrs
51°N, 112°W
cell towers +/- 500 m
Google db of tower locations
Wi-Fi +/- 30 m iPhone GPS +/- 10 m
iPhone uses reference network
db
Graphic courtesy of Wired, Feb. 2009
Skyhook servers and db
A GIS links attribute and spatial data • Attribute Data • Flat File or DBMS • Relationships • Topology Table
• Map Data • • • •
Point File Line File Area File Topology Type
GIS - Links Data Sets • GIS software links the location data and the attribute data:
Potential GIS database 1 megabyte
1 000 000
Single dataset in small project database
1 gigabyte
1 000 000 000
Entire street network of a large city or small country
1 terabyte
1 000 000 000 000
Elevation of entire Earth surface recorded at 30 m intervals
1 petabyte
1 000 000 000 000 000
Satellite image of entire Earth surface at 1 m resolution
1 exabyte
1 000 000 000 000 000 000
A future 3-D representation of Entire Earth at 10 m resolution
1 megabyte
1 gigabyte
1 terabyte
1 exabytes
Advantages of Database over files • • • • • • •
Reducing redundancy Decreasing costs Allowing multiple applications Transfer of knowledge Data sharing Security and standards Concurrent users
Disadvantages • Cost • Complexity • Single user performance decreased
Database Management Systems • Software application designed to organize the efficient and effective storage and access of data
• DBMS capabilities: • • • • • • • • • •
A data model Data load capability Indexes A query language
System Geographic Information System
Security Controlled update Backup & recovery Database administration tools Applications Applications programmings interface (APIs)
• All large GIS databases are based on DBMS
Database Management System
technology
Data