An Introduction to GIS and GPS Technology

1. An Introduction to GIS and GPS Technology Bo Shen March 5, 2004

2. Overview • What is GIS? • GIS Application • GIS Data • GIS Technology(ArcGIS) • What is GPS? • What does the GPS do? • How it works • Application with GIS and GPS • Pocket Street • Automated Vehicle Location System

3. A definition of GIS • GIS (-Geographic Information Systems) is a computer software, hardware and data, and personnel to help manipulate, analyze and present information that is tied to a spatial location. • spatial location–usually a geographic location

4. What is GIS • Different layers • Typically a GIS is used for handling maps of one kind or another. • These might be represented as several different layers where each layer holds data about a particular kind of feature. • Each feature is linked to a position on the graphical image of a map • “Smart Maps”: • linking database to maps.

5. GIS–One example with Five Data Layers

6. Maps and Database are Interactive

7. Some ways of using GIS Technology Wherever Spatial Data Analysis is Needed • Emergency Services– Fire & Police • Environmental – Monitoring & Modeling • Business– Site Location, Delivery Systems • Industry– Transportation, Communication, Mining, Pipelines, Healthcare • Government – Local, State, Federal, Military • Education– Research, Teaching Tool, Administration

8. GIS Application • In the past, • Survey data was first read into a computational program, where errors are eliminated and point coordinates reduced. • The reduced data is then transferred to a CAD program and complemented with construction elements • Finally the data is transferred to a central system.

9. GIS Application Today • Today’s modern systems allow data to be transferred directly to the GIS database. • All information is immediately available for further processing such as correcting errors, performing calculations, etc.

10. GIS Application Today • Handheld GIS computer system • GPS based interface • Commercial GIS data sources • Internet based data server

11. Data flow For GIS Application

12. Data Sources for GIS • Digitized and Scanned Maps • – purchased, donated, free (Internet) • – created by user • DataBases –Tables of data • GPS – Global Positioning System – accurate locations • Remote Sensing & Aerial Photography

13. Data Store Vector Formats –Discrete representations of Reality – give specific spatial locations explicitly –geographic space is continuous, not quantized – attributes are stored separately from locations Raster Formats –use square cells to model reality – Matches hardware nicely – Reduced spatial precision –Large storage requirements

14. Raster Data Compression • Run-length encoding • Chain codes • Quadtrees

15. Run-length Encoding

16. Chain Codes

17. Quadtree Quadtree starts with entire map divided into quadrants. Each quadrant is subdivided until it is homogeneous. • Four quadrants are: NW, NE, SW, and SE • smallest unit is a grid cell

18. Data Query • Identifying specific features • Identifying features based on conditions Florida counties with a population greater than 300,000

19. Data Analysis

20. Data Display

21. Data Output

22. GIS based on many disciplines and technologies • – Geography • – Cartography • – Computer science • – Mathematics • – Statistics • – Remote sensing/GPS/surveying • – Telecommunications/Internet • – Operations research/information science

23. GIS Technology: Software • GIS softwareprovides the functions and tools needed to store, analyze, and display information about places. • The key components of GIS software are • Tools for entering and manipulating geographic information such as addresses or political boundaries • A database management system (DBMS) • Tools that create intelligent digital maps you can analyze, query for more information, or print for presentation • An easy-to-use graphical user interface (GUI) • Major GIS software • ARCGIS (ArcView 8.1)

24. ArcView GIS Data Sets • The GIS Data set used • Shape file • Consisting of : • Shape file (*.shp) • Shape Index (*.shx) • Database table (*.dbf) • Additional files may be present and required as well

25. ArcView GIS • Three Principles Modules • ArcCatalog • ArcMap • ArcToolbox

26. ArcCatalog • A window into your database • Browse your data • Manage your data • Create and view data documentation

27. ArcMap • Primary display application • Perform map-based tasks • Displaying • Editing • Querying • Analyzing • Charting • Reporting

28. ArcToolbox • Major functions: • Data management, analysis, and conversion • Variation of tools between ArcGIS products

29. GIS Resources • GIS Information University of California Berkeley, GIS libraryhttp://sunsite.berkeley.edu/GIS/gisnet.html Spatial Odyssey, University of Maine, GIS Literature Databasehttp://wwwsgi.ursus.maine.edu/ • GIS Software Sources • Environmental Systems Research Institute, Inc. (ESRI)http://www.esri.com/ • MapInfohttp://www.mapinfo.com/ • Intergraph http://www.intergraph.com/dynamicdefault.asp • AutoCADhttp://usa.autodesk.com/adsk/servlet/home?siteID=123112&id=129446 • Clark Labs http://www.clarklabs.org/

30. Global Positioning System (GPS) The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S.Department of Defense. GPS satellites • 24 Satellites in 6 planes, each plane has 4 satellites • These space vehicles (SVs) send radio signals from space.

31. What does the GPS do • Satellite signals can be processed in a GPS receiver. • GPS receiver will show your EXACT location on the Earth (latitude and longitude) • Helps you find your way to a specified location • Let’s you know what direction you are heading and how fast you are going

32. GPS- How it works • Measuring the distance from a satellite by measuring travel time of radio signals seconds Distance = speed of light * latency in time • Four GPS satellite signals are used to compute positions in three dimensions and the time offset in the receiver clock.

33. GPS- How it works • Given 1 satellite … • We can locate our position on the surface of a sphere

34. GPS- How it works • Given 2 satellites • We can locate our position on the intersection of 2 spheres (a circle)

35. GPS- How it works • Given 3 satellites … • We can locate our position on the intersection of 3 spheres (2 points)

36. GPS-How it works • Given 4 satellites … • We can locate our position on the intersection of 4 spheres (1 point). The point should be located on the earth’s surface

37. GPS- How it works • The GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. • With four or more satellites in view, the receiver can determine the user's 3D position (latitude, longitude and altitude).

38. Pocket Streets- an example with GPS and GIS • Pocket Streets offers exciting features such as street-smart mapping, map customization, GPS and Microsoft Outlook integration. • With Pocket Streets on your Pocket PC, you will take a smart map with you wherever you go.

39. Pocket Streets- an example with GPS and GIS • Download the map for the city. • Connect the GPS receiver to Pocket PC. • Choose "Track Position" from the GPS menu to show your current position on the map. • The position moves when you move.

40. Pocket Streets- an example with GPS and GIS • Tap-and-Hold on either a Contact with an address, or a Calendar appointment that has an address in the location. • Choose "Find On Map" from the pop-up menu to show the location in Pocket Streets.

41. Pocket Streets- an example with GPS and GIS • With GPS, you can get your Current Location. • From the outlook, you get the Address of your contacts and GIS Will find the location on the map. • So, Pocket Street will guide you to your destination

42. Automated Vehicle Location System • Where is the bus • What direction is the bus traveling to • What is the travel speed • Where is stop • How long is the stop

43. Automated Vehicle Location System How Do GPS , GIS and AVL Relate? • GPS receiver calculates its position (latitude and longitude) and record the information at fixed time interval • GPS transmitter transmits location and vehicle dynamic data to control center at prescribed interval • Control center system process data accoding to customer specifications • GIS Software display filtered information on the screen with map layer

44. Automated Vehicle Location System

45. Conclusions • GPS can show your EXACT location on the Earth (latitude and longitude) • GIS provides several different map layers where each layer holds data about a particular kind of feature related to spatial data. • Using GIS and GPS we can capture, management, analysis, modeling and display geographically referenced data for decision making. It is a way in which to begin to represent and model the real world.