National Wildfire Coordinating Group

GPS Use for GIS Application

Set up before going to the field

  • Make sure fresh batteries are loaded and extra sets available.
  • Transfer background maps for the area using MapSource (if available).
  • Turn unit on to initialize and acquire satellites ahead of time if you are in a new area or haven’t used the unit in at least a week. This may take as long as 20 minutes in the open, away from buildings, canopy, and obstructions.
  • Download and clear old waypoints and tracks from memory.
  • Turn off Active Track log. Set it to the preferred Collection method (Time is best) and an appropriate logging rate for the data collection. Five seconds works for most walking collection. Keep in mind the total storage of the GPS.
  • Ensure Simulator Mode is not ON when collecting data.
  • Set unit time zone and date (Ensure Daylight Savings Time if needed).
  • Check Interface Protocol is set properly.
  • Set the Coordinate System (UTM or LAT/LONG) & Datum to ensure compatibility with written coordinates you may need to navigate to or Map.
  • Set Heading to magnetic or true. If true, ensure same declination is used.

Field – GPS Data Collection

  • Hold GPS antenna away from body with antenna up. Better yet, hold at, or above the head. Purchase an external antenna to free hands if needed or for better reception in vehicles.
  • Mark the waypoints for point locations at beginning and ending of track log collections. Writing down a position is just backup.
  • Most GPS units will collect data no matter what the GPS quality is. It’s up to you to monitor the GPS Satellite Page for anomalies and accuracy.
  • Collect when 3D GPS is shown. Do not collect data in 2D unless necessary.


  • Collect all waypoints in Averaged Position mode if you are standing still, when possible, and if your receiver has that capability. Minimum of 10 positions, maximum of 20 minutes. Somewhere in between is enough to generate a quality position in most cases.
  • Collect an instantaneous waypoint only when moving or in a hurry, or if using the eTrex line.
  • Edit default waypoint numbers to letters or words that are more descriptive, or make good field notes to ensure you remember what features are represented by which numbers.

Track logs

  • Use Stop when Full or Fill Record Mode rather than wrap to prevent overwriting track log points when Active Track log becomes full.
  • Turn on Active Track log at start location and immediately begin moving.
  • Stop Active Track log when movement is stopped or mission is finished.
  • Always Stop Active Track just shy of starting point when collecting an area (polygon). Overlapping makes conversion to GIS more challenging.
  • Use caution when saving an Active Track log. Garmin will generalize active track to save space, thereby degrading data.



PRINT FBFRG GPS Use for GIS Application
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