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
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
Global Positioning System
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.
GPS Component Parts Space Segment Control Segment User Segment
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
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
User Segment GPS receiver equipment: Us! Receives signals from GPS satellites Calculates user s three-dimensional position
Triangulation Triangulation is a basic geometric principle that allows you to find one location if you know its distance from other, already known locations.
How GPS Works One satellite
How GPS Works If the GPS receiver only obtains signals from 1 Satellite, then it knows that it is located somewhere on this sphere
How GPS Works Two satellites
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
How GPS Works Three satellites
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)
How GPS Works Four satellites
How GPS Works A fourth satellite is required to determine the exact location and elevation.
Geographic Information Systems
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
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
What is GIS?
Multiple Layers or Themes
Site Assessment: Identifying an appropriate location for a vineyard Elevation + Aspect Soil Types Pests + Disease Access to market Irrigation Weather + Climate
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
Waypoints Waypoint 2 Waypoint 3 Latitude: 37 16 18 Longitude: W80 28 45 Elevation: 2108 feet Waypoint 1
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
Tracks (just start walking )
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
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
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
Polygons (acreage calculation) 61.5 Acres
Waypoints at Field Corners 010 001 002 007 009 008 61.5 Acres 006 003 005 004
Low-Cost GPS Units
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
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 50-65 feet
Low-Cost GPS Unit Providers
Garmin www.garmin.com 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
Magellan www.magellangps.com 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
The Garmin GPSMAP 60CSx
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. 1000 waypoints, 50 routes, 20 saved tracks with 10,000 points
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
Garmin GPSMAP 60CSx
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
Free and Low-Cost Mapping Software
ArcGIS Explorer by ESRI www.esri.com Free
Google Earth by Google http://earth.google.com Google Earth Free Google Earth Pro 7 day free trial $400
ExpertGPS by Topografix www.topografix.com 30 day free trial ExpertGPS Home $59.95 ExpertGPS Pro with GIS and CAD/DXF Options $159.95
Other software: DNR Garmin http://www.dnr.state.mn.us/mis/gis/tools/arcvie 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
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
Video Tutorials
Any Questions?
Contact Information: Chris Dillard Extension Specialist, Geospatial Technologies Alabama Cooperative Extension System 110 Extension Hall Auburn University, AL 36849 Office: (334) 844-3921 Mobile: (334) 728-3921 Email: dillach@aces.edu