1. GTECH 709 Geographic data
Geo-relational principle - again Geographic data organization
Back to the map

2. What is Geographic Data?
Following the geo-relational principle, geographic data has to have
A locational reference
Check for yourself about all the different ways we can specify a location
Data that describes what can be found at that location:
Income, temperature, party affiliation, soil type, etc.

3. Geographic Data Organization
We will have whole sessions on this
Location and attributes in one file
Latitude
Longtitude
Precision
Address
City
State
ZIP
Name
Description
51.514
109 Cheapside
London UK
EC2V 6
GIS Cloud
Web-based GIS
38.967
555 Grove St
Herndon VA
20170
Juice Analytics
Data analysis
37.416
701 First Ave
Sunnyvale CA
94089
Yahoo
Address matching
37.423
1600 Amphitheater Pkwy
Mountain View
94043
Google
Google Earth
47.643
Street
One Microsoft Way
Redmond WA
98052
Microsoft
Excel
41.132
1 New Orchard Rd
Armonk NY
10504
IBM
You tell me

4. Geographic Data Organization
Location and attributes in multiple files
ESRI “shapefile”
A collection of .shp, .dbf, .shx files
Location and attributes in a database (file)
ESRI geodatabases
PostGIS database
Web services

5. Back to the Map
A digital map is a set of instructions on how to arrange visual representations of geography
Items such as a Google map or a satellite image may serve as context
We can turn map layers on or off
Label map elements
Change appearances