Evaluating Handheld GPS Evaluating Handheld GPS Receivers for Recording Receivers for Recording

Archaeological Survey DataArchaeological Survey Data

GEO444 – Practical GPSGEO444 – Practical GPSWilliam Eichmann and Jake ReidelWilliam Eichmann and Jake Reidel

Archaeological Survey DataArchaeological Survey Data

Survey areas:Survey areas: agricultural field boundaries, agricultural field boundaries, areas surveyed, surface conditions, transect areas surveyed, surface conditions, transect interval, often visible on satellite images, interval, often visible on satellite images, polygons, certainty=10m.polygons, certainty=10m.Individual artifacts:Individual artifacts: “isolated finds” reflect diffuse “isolated finds” reflect diffuse activities across landscape, diagnostic artifacts, activities across landscape, diagnostic artifacts, points, certainty=2-5m.points, certainty=2-5m.Sites:Sites: concentrated areas of material culture, concentrated areas of material culture, amorphous and fuzzy boundaries, comprised of amorphous and fuzzy boundaries, comprised of individual artifacts, polygons, certainty=10m.individual artifacts, polygons, certainty=10m.

Time and CostTime and Cost

How much time does the method take How much time does the method take relative to other methods?relative to other methods?

How does it compare with other methods How does it compare with other methods in terms of accuracy?in terms of accuracy?

Field Site: UW AboretumField Site: UW Aboretum

Google EarthGoogle Earth

MethodsMethods

VehicleVehicle2 recievers Garmin Etrex and Vista2 recievers Garmin Etrex and VistaDigital cameraDigital cameracomputercomputerSoftware:Software: GPS Babel, Google Earth pro. GPS Babel, Google Earth pro.Date of fieldwork:Date of fieldwork: 2008.05.05 2008.05.05Time of fieldwork:Time of fieldwork: 16:47-18:50 16:47-18:50Waypoints:Waypoints: measured for 1 min. measured for 1 min.Tracks measurement frequency:Tracks measurement frequency: 5 sec. (p14), 30sec 5 sec. (p14), 30sec (p12)(p12)

Data AnalysisData Analysis

Field conditionsField conditions

WaypointsWaypoints

Results: Waypoints / RoutesResults: Waypoints / Routes

MaskingMasking

TracksTracks

Visual ComparisonVisual Comparison

DiscussionDiscussion

Both waypoints/routes and tracks are sufficiently Both waypoints/routes and tracks are sufficiently accurate and precise for defining field and site accurate and precise for defining field and site boundaries.boundaries.Tracks take less time and provide better Tracks take less time and provide better accuracy with similar precision to accuracy with similar precision to waypoints/routeswaypoints/routesTracks may be better suited to recording Tracks may be better suited to recording amorphous shapes of sitesamorphous shapes of sitesRecord individual artifacts as waypoints.Record individual artifacts as waypoints.Tall vegetation masks satellitesTall vegetation masks satellites

Conclusion and ImprovementsConclusion and Improvements

Survey areas: collect several control Survey areas: collect several control points and define fields based on satellite points and define fields based on satellite images.images.

Individual artifacts: record as waypointsIndividual artifacts: record as waypoints

Sites: record with tracksSites: record with tracks

Equipment: use a GPS receiver/data Equipment: use a GPS receiver/data collector with loaded background images. collector with loaded background images.