Types of standard coordinate systems: UTM, State Plane, Texas State Mapping System, Standard Hydrologic Grid•Spatial Reference in ArcGIS 10 requires projection and map extentdr gemson, IIAEM, JU, Bangalore104
Learning Objectives:By the end of this class you should be able to:•describe the role of geodesy as a basis for earth datums•Display data from GPS in ArcMap and Google Earth•list the basic types of map projection•identify the properties of common map projections•properly use the terminology of common coordinate systems•use spatial references in ArcMap so that geographic data is properly displayed•determine the spatial reference system associated with a feature class or data frame•use ArcGIS to convert between coordinate systems •calculate distances on a spherical earth and in a projected coordinate systemdr gemson, IIAEM, JU, Bangalore105
(Press and hold)Trimble GeoXHTMGarmin GPSMAP 276C GPS Receiver Global Position Systemsdr gemson, IIAEM, JU, Bangalore107
How GPS works in five logical steps: 1.The basis of GPS is triangulation from satellites2.GPS receiver measures distance from satellite using the travel time of radio signals3.To measure travel time, GPS needs very accurate timing 4.Along with distance, you need to know exactly where the satellites are in space. Satellite location. High orbits and careful monitoring are the secret5.You must correct for any delays the signal experiences as it travels through the atmospheredr gemson, IIAEM, JU, Bangalore108
GPS SatellitesSatellites are distributed among six offset orbital planes•24 satellites•6 orbital planes•12 hour return interval for each satellitedr gemson, IIAEM, JU, Bangalore109
Distance from satellite•Radio waves = speed of light•Receivers have nanosecond accuracy (0.000000001 second)•All satellites transmit same signal “string” at same time•Difference in time from satellite to time received gives distance from satellitedr gemson, IIAEM, JU, Bangalore110
Triangulationdr gemson, IIAEM, JU, Bangalore111
Triangulationdr gemson, IIAEM, JU, Bangalore112
GPS location of Mabel Lee Hall, University of Nebraska, Lincolndr gemson, IIAEM, JU, Bangalore113
dr gemson, IIAEM, JU, Bangalore114Meridian section of the Earth, showing the reference ellipsoid and gravity field.
dr gemson, IIAEM, JU, Bangalore115
dr gemson, IIAEM, JU, Bangalore116For navigational purposes, the Earth's surface can be represented by an ellipsoid of rotation around the Earth's spin axis. The size and shape of the best-fitting ellipsoid are chosen to match the sea-level equipotential surface.
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- Summer '18