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Initial Laser Pulse. ~400 m altitude. Surface Return. 0.5 * t / c = Depth. Bottom Return. <50 m depth. CHARTS Lidar DGPS Operating Principle. UNCLASSIFIED. CHARTS Lidar DGPS Operating Principle. GPS Constellation. Raw depths and elevations referenced to water level
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Initial Laser Pulse ~400 m altitude Surface Return 0.5 * t / c = Depth Bottom Return <50 m depth CHARTS Lidar DGPSOperating Principle UNCLASSIFIED
CHARTS Lidar DGPSOperating Principle GPS Constellation Raw depths and elevations referenced to water level In-situ or predicted tides required to reduce data to chart datum UNCLASSIFIED
HydroMap Tide Model (ftp://ftp.seal.navy.smil.mil/mscwest-inbox/) UNCLASSIFIED
Initial Laser Pulse ~400 m altitude 0.5 *t / c = aircraft to bottom distance Bottom Return <50 m depth CHARTS Lidar KGPSOperating Principle UNCLASSIFIED
From benchmark datasheet From simultaneous measurements From averaged OPUS solution CHARTS Lidar KGPSOperating Principle Raw depths and elevations referenced to level of GPS base station. Distance from WGS84 ellipsoid to chart datum must be measured. GPS Constellation Tidal datums MUST be calculated • Base Station Vertical Datum Offsets • MHHW: - 56.668 m • MHW: - 56.628 m • MSL: - 56.391 m • MLLW: - 55.999 m GPS Constellation GPS Constellation GPS Base Station Tidal Benchmark 13.103 m MHHW MHW .669 m 56.668 m 2.049 m .629 m MSL .392 m 56.628 m MLLW 56.391 m (h) 58.048 m 55.999 m WGS84 Ellipsoid UNCLASSIFIED