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An Introduction to GIS and GPS Technology

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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 “Smart Maps”: linking database to maps.
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 Raster Formats – use square cells to model reality
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 software provides 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 GIS Software Sources
University of California Berkeley, GIS library Spatial Odyssey, University of Maine, GIS Literature Database GIS Software Sources Environmental Systems Research Institute, Inc. (ESRI) MapInfo Intergraph AutoCAD Clark Labs

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.

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