|2009 USACE Great Lakes Topo/Bathy Lidar: Minnesota
||These files contain bare-earth classified topographic and bathymetric lidar data collected
July 27, 2009 by the Compact Hydrographic Airborne Rapid Total Survey (CHARTS) system
along the coast of Lake Superior near Duluth, Minnesota. CHARTS integrates topographic
and bathymetric lidar sensors, a digital camera, and a hyperspectral scanner on a
single remote sensing platform for use in coastal mapping and charting activities.
Data coverage generally extends along the coastline from the waterline inland 500
meters (topography) and offshore 1,000 meters or to laser extinction (bathymetry).
The topographic lidar sensor has a pulse repetition rate of 9 kHz at 1064 nm (near-infrared
wavelength). The bathymetric lidar sensor has a pulse repetition rate of 1 kHz at
532 nm (green wavelength). Native lidar data is not generally in a format accessible
to most Geographic Information Systems (GIS). Specialized in-house and commercial
software packages are used to process the native lidar data into 3-dimensional positions
that can be imported into GIS software for visualization and further analysis. Horizontal
positions, provided in decimal degrees of latitude and longitude, are referenced to
the North American Datum of 1983 (NAD83). Vertical positions are referenced to the
NAD83 ellipsoid and provided in meters. The National Geodetic Survey's (NGS) GEOID03
model is used to transform the vertical positions from ellipsoid to orthometric heights
referenced to the North American Vertical Datum of 1988 (NAVD88). For data storage
and provisioning purposes, the NOAA Coastal Services Center converted the data from
NAVD88 heights to ellipsoid heights using GEOID03.