GPS 101: Introduction to Geospatial Technologies Alabama Forest Owners Association Annual Meeting

Transcription

1 GPS 101: Introduction to Geospatial Technologies Alabama Forest Owners Association Annual Meeting Chris Dillard Geospatial Extension Specialist Alabama Cooperative Extension System April 17 th, 2010

2 Outline Introduction to GPS Introduction to GIS Introduction to the Garmin GPSMAP 60CSx Low-Cost GPS units Free and low-cost mapping software Outdoor cruising/sampling exercise Create a sampling grid/transfer to GPS unit Navigate using grid and collect points Transfer points to software and map

3 Global Positioning System

4 What is GPS? The Global Positioning System (GPS) is a U.S. space-based radionavigation system that provides reliable positioning, navigation, and timing services to civilian users on a continuous worldwide basis -- freely available to all.

5 GPS Component Parts Space Segment Control Segment User Segment

6 Space Segment 24 satellites orbit ~12,900 miles above Earth Approximately 6 spare satellites DOD knows the EXACT location of each of the satellites at any given moment Have very accurate clocks on board Continuously send one-way radio signals Signals continuously provide position and time to GPS receivers

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8 Control Segment Five worldwide monitor and control stations Provides orbital maneuver commands Adjusts satellite clocks Tracks satellites Uploads updated navigational data Maintains health and status of the satellite constellation

9 User Segment GPS receiver equipment: Us! Receives signals from GPS satellites Calculates user s three-dimensional position

10 Triangulation Triangulation is a basic geometric principle that allows you to find one location if you know its distance from other, already known locations.

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14 How GPS Works One satellite

15 How GPS Works If the GPS receiver only obtains signals from 1 Satellite, then it knows that it is located somewhere on this sphere

16 How GPS Works Two satellites

17 How GPS Works If the GPS receiver only obtains signals from 2 satellites, then it knows that it is located somewhere where these 2 spheres intersect

18 How GPS Works Three satellites

19 How GPS Works If the GPS obtains signals from 3 satellites, then it knows that it is located somewhere where these 3 spheres intersect (2 points)

20 How GPS Works Four satellites

21 How GPS Works A fourth satellite is required to determine the exact location and elevation.

22 Geographic Information Systems

23 What is a GIS? A geographic information system, or GIS, integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information. - ESRI

24 What is a GIS? Georeferenced data contains coordinate information (latitude and longitude, e.g.) GIS uses layers, called "themes," to overlay different types of information Display and analyze spatial data which are tied to databases This connection is what gives GIS its power: maps can be drawn from the database and data can be referenced from the maps

25 What is GIS?

26 Multiple Layers or Themes

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28 Site Assessment: Identifying an appropriate location for a vineyard Elevation + Aspect Soil Types Pests + Disease Access to market Irrigation Weather + Climate

29 What can you do with a GPS receiver? Collect and store points (waypoints) Indicate a single position Field corners, insect infestation areas, crop damage, individual trees, trail heads, creek crossings, point source pollution, etc. Download points onto your computer and integrate with other data

30 Waypoints Waypoint 2 Waypoint 3 Latitude: Longitude: W Elevation: 2108 feet Waypoint 1

31 What can you do with a GPS receiver? Collect and store lines or tracks Calculate distance (perimeter of a field, e.g.) May represent a road, stream, or path Save and download tracks onto your computer

32 Tracks (just start walking )

33 What can you do with a GPS receiver? Collect and store routes Routes are similar to tracks, but are created using waypoints Routes can be handy for measuring square fields and straight lines

34 1. Establish Waypoints at strategic locations The GPS Receiver Connects the dots 1. Area and perimeter measurements are generated Routes #6 #5 #1 #2 #3 #4

35 What can you do with a GPS receiver? Collect and store polygons Polygons are fully enclosed May represent a pasture, pond, or tract of timber Measure field or pond acreage

36 Polygons (acreage calculation) 61.5 Acres

37 Waypoints at Field Corners Acres

38 Low-Cost GPS Units

39 GPS Purchasing Considerations WAAS enabled Accuracy (generally 3-5 meter) Great accuracy = greater costs Data file type Transfer data to a computer Included software Battery life Technical support Ruggedness

40 Data Collection Most units allow waypoint, track, and route creation Not all units provide area calculation Area can be calculated with mapping software using collected tracks WAAS-enabled units can provide greater accuracy Elevation data is not very accurate Only accurate to feet

41 Low-Cost GPS Unit Providers

42 Garmin Carry a variety of units Road, marine, trail, and aviation Prices range from ~ $100-$600 Includes basic data management software Some accept more detailed maps Road, marine, topographic, e.g. DVD, microsd, SD, and downloadable formats Most include a basemap (primary roads) May be purchased online and at local retailers

43 Magellan Carry a variety of units Road, marine, and trail Prices range from ~$130-$450 Include basic data management software Accept more detailed maps Road, marine, topographic, e.g. DVD, CD, SD, and downloadable formats Include built-in basemaps May be purchased at website and online retailers

44 The Garmin GPSMAP 60CSx

45 Garmin GPSMAP 60CSx From Garmin On the Trail, Mapping series High sensitivity receiver WAAS enabled 3-5 meter accuracy (10-16 feet) 95% typical 18 hour battery life, typical (2 AA) Waterproof Ability to load detailed maps Lakes, roads, coastlines, topographic, etc waypoints, 50 routes, 20 saved tracks with 10,000 points

46 Garmin GPSMAP 60CSx Features Automatic road routing Electronic compass Barometric altimeter Geocaching-friendly Outdoor GPS games Hunting/fishing calendar Sun and moon information Area calculation Custom points-of-interest

47 Garmin GPSMAP 60CSx

48 Status Bar Auxiliary Power icon (powered by external source) Satellite signal status (3D: four or more satellites) Electronic compass icon (on) USB cable icon (connected) Backlight icon 2D fix: three satellites minimum, no elevation Acquiring satellites Battery power icon

49 Free and Low-Cost Mapping Software

50 ArcGIS Explorer by ESRI Free

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52 Google Earth by Google Google Earth Free Google Earth Pro 7 day free trial $400

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54 ExpertGPS by Topografix 30 day free trial ExpertGPS Home $59.95 ExpertGPS Pro with GIS and CAD/DXF Options $159.95

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56 Other software: DNR Garmin w/extensions/dnrgarmin/dnrgarmin.html Minnesota Department of Natural Resources Garmin data transfer utility Provides users the ability to directly transfer data between Garmin GPS handheld receivers and various GIS software packages

57 GPS/GIS Exercise Open an aerial image (freely available) Create a sampling/cruising grid over a field Transfer the grid to the GPS unit Navigate through the field using the grid Collect a waypoint within each grid square Verifies that each grid square has been visited Transfer the waypoints into the GIS software

58 Video Tutorials

59 Any Questions?

60 Contact Information: Chris Dillard Extension Specialist, Geospatial Technologies Alabama Cooperative Extension System 110 Extension Hall Auburn University, AL Office: (334) Mobile: (334)