1. GTECH 709 Principles of GIS
Spatial relationships
Scale
Time
Earth from above
The acronym
Disciplinary background
Representation
Geo-relational principle
Maps vs. Geography 1

2. GTECH 709 Thinking like a geographer
Space is everywhere 2

3. Tobler's First Law
(Waldo) Tobler'sFirst Law of Geography

4. Tobler's First Law (Waldo) Tobler'sFirst Law of Geography
Everything is related to everything else, but those things closer to each other are also more related with each other

5. Spatial Thinking Making a decision on where to take your next vacation
Determining whether or not you can make it to the next rest area

6. Tabular Data # Annoying People Total Population Average Age
Average Income
# of SUVs
County
State 72
998 26
48,000
Hatchback
Wholefood 48
2,000 65
32,000
Dialupia
776
2,250 44
72,000
750
Sriracha
Traderjo
789
3,500 36
12,000
700
Muffintown
469
1,200 31
22,500
461
Fixieplaid
525
1,400 42
66,000
400
Burb-on-Burb 62 33
92,000 59
Bluetooth Village
230
16,450 51
35,000
1,950
Pabsto
9,654
52,510
49,000
8,192
University Collegeville
779
1,459 41
61,000
398
Kingo 6

7. Thinking Like a Geographer

8. Thinking Like a Geographer
Choropleth Map = areas filled with colors to represent a range of values

9. Space is Everywhere!

10. Twitter Locations

11. GTECH 709 Spatial relationships
Topological relationships .. and their importance

12. Spatial Relationships (1)
Equals
A is the same as B
Touches
A touches B
Overlaps
A and B have multiple points in common
Contains
A contains B

13. Spatial Relationships (2)
Disjoint
A shares nothing with B
Covers
A covers B
Crosses
A and B have at least one point in common B A A B A B

14. Ignore at your Own Risk What would happen if we ignored them?
Mapquest and Google Maps would be useless
Consider 500 road segments of your neighborhood collected with a GPS

15. GTECH 709 Scale
Map scale
Spatial resolution
Scale of analysis

16. Map Scale
The scale you learned about in Geography / cartography

17. Spatial Resolution
The smallest element discernable / stored in your database

18. Scale of Analysis
Specific geographic context used to understand a problem

19. All three influence each other
Scale
All three influence each other

20. GTECH 709 Time in GIS Integral component of geographic data
Hard in/for GIS

21. Time
Almost everything geographic involves a dynamic process of one type or another

22. Time
Almost everything geographic involves a dynamic process of one type or another
Geography = ƒ (space, time, attributes)

23. Time
Almost everything geographic involves a dynamic process of one type or another
Geography = ƒ (space, time, attributes)
Static maps make it hard to see time as an explicit factor

24. Time

25. GTECH 709 Locations
Where are we?
How do we get out location?

26. Locations Where are we now?
Used to be a hard question involving complicated instruments and specialist training

27. How Do We Get Our Location
Smartphones and consumer-grade GPS
Often augmented by wifi and cellphone tower data
Positional accuracy between ten and 1,000 feet
Professional surveying-grade systems provide sub-feet accuracy
Hunter Geography lab is at a point defined as /

28. How Do We Get Our Location
Classroom is at a point defined as /
If I walked to the elevator, we would create a path line
If we walked around the block, we could create a polygon
Point, lines and polygons form spatial vector data

29. GTECH 709 Earth From Above Reference to parallel course Raster data
Data sources
Application examples

30. GTECH 711 Virtual globe tools like Google Earth
Most geographic image data comes from satellites and airborne sensors, but you can even make your own DIY drone now
Geographic image data is raster data, which captures information by assigning values to cells in a grid

31. Raster Format
The size of raster grid cells determines how much resolution you have for the image

32. Example 1

33. Example 2

34. Example 3

35. GTECH 709 GIS – the acronym G I S

36. What is GIS? Geographic Information System Scale 1:1K to 1:100M
On or near Earth’s surface
Information
Data and the methods to transform them into information, aka analysis
System
Software
People and institutional settings

37. GTECH 709 Disciplinary background
Core disciplines
Original application areas

38. GIS Core Disciplines Geography Surveying engineering
cartography
Surveying engineering
geodesy
Computer / information science
Databases and graphics systems

39. Inventors of GIS (Canadian) forestry Landscape architecture US Census
 Military

40. GTECH 709 GIS layers
Themed layers
Geometry types

41. GIS Map Organization
Layers

42. GIS Map Organization
Layers
Organized by “theme”

43. GIS Map Organization Layers Organized by “theme”
One geometry at a time

44. GIS Map Organization Layers Organized by “theme”
One geometry at a time
Act as a legend in a separate window

45. Map and Legend Windows

46. GIS Map Organization Layers Organized by “theme”
One geometry at a time
Act as a legend in a separate window
Borrowing from map making / printing history

47. GTECH 709 Representation
Points, lines, polygons

48. Representation
Features
Points
Lines
Polygons

49. GTECH 709 Geo-relational principle
Geometries
Attributes

50. Georelational Principle
Combining map geometries with attributes that describe the geographic characteristics of those geometries

51. Georelational Principle

52. GTECH 709 Maps vs. geography
Revisiting the relationship game

53. Maps versus Geography Remember the relationship game
We use geometries to describe locations on the Earth’s surface
We use attributes (e.g. spreadsheets) to describe what interests us about each of those locations
We use maps to communicate visually about the relationship between locations and what can be found at these locations

54. Maps versus Geography Remember the relationship game
Maps depict usually only one or a small number of attributes at a time
There are as many maps about an area of interest as there are attributes to describe the area
Even with the same attributes, there are myriads of ways to visualize them;  even more maps

55. Maps versus Geography Remember the relationship game
One geographic data set can produce many maps
The map is a visual index to geographic data
The map prompts us to reason about spatial relationships, such as …
You will provide the answer in the quiz

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

57. 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.

58. 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

59. 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

60. 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

61. GTECH 709 GIS as a process
GIS as a sequence of steps GIS as a process of inquiry

62. GIS as a Process 1 Capture data Store data Query data Analyze data
Display data
Present data

63. GIS as a Process 2 Ask a geographic question Acquire geographic data
Explore geographic data
Analyze geographic information
Act on geographic knowledge

64. GTECH 709 Week 2 summary

65. Summary
A GIS organizes and stores information about the world as a collection of thematic layers. Each layer contains features with the same shape and attributes, all located within a common geographic area.
Each feature is assigned a unique numerical identifier and is characterized by a unique location in space and a corresponding record in a table.
Features can be stored in a GIS as three primary shapes: points, lines, or polygons.
Features have spatial relationships with other features, and with a GIS you can find features based on their spatial relationships.
The geographic inquiry process provides a framework for solving problems with GIS.