INTRODUCTION

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