U.S. Geological Survey 2009 first remote-sensing image U.S. Geological Survey Data Series 482 St. Petersburg, FL U.S. Geological Survey A seamless (bare earth and submerged) elevation map (also known as a Digital Elevation Model, or DEM) of a portion of western Florida, post-Hurricane Charley was produced from remotely sensed, geographically referenced elevation measurements cooperatively by the U.S. Geological Survey (USGS) and the National Aeronautics and Space Administration (NASA). Elevation measurements were collected over the area using the NASA Experimental Advanced Airborne Research Lidar (EAARL), a pulsed laser ranging system mounted onboard an aircraft to measure ground elevation, vegetation canopy, and coastal topography. The system uses high-frequency laser beams directed at the Earth's surface through an opening in the bottom of the aircraft's fuselage. The laser system records the time difference between emission of the laser beam and the reception of the reflected laser signal in the aircraft. The plane travels over the target area at approximately 50 meters per second at an elevation of approximately 300 meters. The EAARL, developed by NASA at Wallops Flight Facility in Virginia, measures ground elevation with a vertical resolution of +/-15 centimeters. A sampling rate of 3 kilohertz or higher results in an extremely dense spatial elevation dataset. Over 100 kilometers of coastline can be surveyed easily within a 3- to 4-hour mission. When subsequent elevation maps for an area are analyzed, they provide a useful tool to make management decisions regarding land development. The purpose of this project was to produce a highly detailed and accurate seamless (bare earth and submerged) elevation map of a portion of western Florida, post-Hurricane Charley for use as a management tool and to make these data available to natural-resource managers and research scientists. Raw lidar data are not in a format that is generally usable by resource managers and scientists for scientific analysis. Converting dense lidar elevation data into a readily usable format without loss of essential information requires specialized processing. The U.S. Geological Survey's Coastal and Marine Geology Program (CMGP) has developed custom software to convert raw lidar data into a GIS-compatible map product to be provided to GIS specialists, managers, and scientists. The primary tool used in the conversion process is Airborne Lidar Processing System (ALPS), a multi-tiered processing system developed by a USGS-NASA collaborative project. Specialized processing algorithms are used to convert raw waveform lidar data acquired by the EAARL to georeferenced spot (x,y,z) returns for "first surface" and "bare earth" topography. The zero crossing of the second derivative (i.e., detection of local maxima) is used to detect "first surface" topography, while the trailing edge algorithm (i.e., the algorithm searches for the location prior to the last return where direction changes along the trailing edge) is used to detect the range to the last return or "bare earth". Statistical filtering, known as the Random Consensus Filter (RCF), is used to remove false bottom returns and other outliers from the EAARL topography data. The filter uses a grid of non-overlapping square cells (buffer) of user-defined size overlaid onto the original point cloud. The user also defines the vertical tolerance (vertical width) based on the topographic complexity and point sampling density of the data. The maximum allowable elevation range within a cell is established by this vertical tolerance. An iterative process searches for the maximum concentration of points within the vertical tolerance, and removes those points outside of the tolerance (Nayegandhi and others, 2009). These data are then converted to the North American Datum of 1983 and the North American Vertical Datum of 1988 (using the GEOID03 model). Each file contains data located in a 2-kilometer by 2-kilometer tile, where the upper-left bound can be assessed quickly through the filename. The first 3 numbers in the filename represent the left-most UTM easting coordinate (e###000) in meters, the next 4 numbers represent the top-most UTM northing coordinate (n####000) in meters, and the last 2 numbers (##) represent the UTM zone in which the tile is located (for example, sm_e123_n4567_17). The development of custom software for creating these data products has been supported by the U.S. Geological Survey CMG Program's Decision Support for Coastal Parks, Sanctuaries, and Preserves Project. Processed data products are used by the U.S. Geological Survey CMG Program's National Assessments of Coastal Change Hazards Project to quantify the vulnerability of shorelines to coastal change hazards such as severe storms, sea-level rise, and shoreline erosion and retreat. 20040817 20040818 ground condition Complete None planned ISO 19115 Topic Category elevation None http://remotesensing.usgs.gov/ Airborne Lidar Processing System ALPS Digital Elevation Model DEM EAARL Experimental Advanced Airborne Research Lidar laser altimetry lidar remote sensing topography http://nationalmap.gov/ western Florida Hurricane Charley http://lidar.cr.usgs.gov/ seamless (bare earth and submerged) http://www.esri.com/news/arcuser/1104/temporal.html 2004 None The U.S. Geological Survey and the National Aeronautics and Space Administration request to be acknowledged as originators of these data in future products or derivative research. Amar Nayegandhi Jacobs Technology, U.S. Geological Survey, CMGP, St. Petersburg, FL Computer Scientist mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 803-8747 (x3026) 727 803-2031 anayegandhi@usgs.gov M-F, 8:30-5:00 EST Acknowledgment of the U.S. Geological Survey, Coastal and Marine Geology Program, as a data source would be appreciated in products developed from these data, and such acknowledgment as is standard for citation and legal practices for data source is expected. Sharing of new data layers developed directly from these data would also be appreciated by the U.S. Geological Survey staff. Users should be aware that comparisons with other datasets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in photointerpretation, mapping conventions, and digital processes over time. These data are not legal documents and are not to be used as such. Unclassified Unclassified None Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.1.1850 3.5800 E+53.5600 E+52.99400 E+62.99200 E+63.5800 E+53.5600 E+52.99200 E+62.99400 E+6Nayegandhi, A., Brock, J.C., and Wright, C.W.2009International Journal of Remote Sensing30(4), p. 861-878 The expected accuracy of the measured variables is as follows: attitude within 0.07 degree, 3 centimeters nominal ranging accuracy, and vertical elevation accuracy of +/-15 centimeters for the topographic surface. Quality checks are built into the data-processing software. Each file contains data located in a 2-kilometer by 2-kilometer tile where the upper-left bound can be assessed quickly through the filename. The first 3 numbers in the filename represent the left-most UTM easting coordinate (e###000) in meters, the next 4 numbers represent the top-most UTM northing coordinate (n####000) in meters, and the last 2 numbers (##) represent the UTM zone in which the tile is located (for example, sm_e123_n4567_17). Several regions of the dataset are labeled as "No Data," which corresponds to a cell value of -32767 meters in the GeoTIFF file. These "No Data" areas are a result of the survey not covering a particular region (for example, behind the beachface), optical water depth of greater than 1.5 Secchi disc depths, or the manual removal of lidar processing artifacts. The presence of "No Data" values does not necessarily indicate an absence of land, rather, an absence of survey coverage. Raw elevation measurements have been determined to be within 1 meter in horizontal accuracy. Elevations are vertically consistent with the point elevation data, +/-15 centimeters. The data are collected using a Cessna 310 aircraft. The NASA Experimental Advanced Airborne Research Lidar (EAARL) laser scanner collects the data using a green (532-nanometers) raster scanning laser, while a digital camera acquires a visual record of the flight. The data are stored on hard drives and archived at the U.S. Geological Survey office in St. Petersburg, Florida and the NASA office at Wallops Flight Facility in Virginia. The navigational data are processed at Wallops Flight Facility. The navigational and raw data are then downloaded into the Airborne Lidar Processing System (ALPS). Data are converted from units of time to x,y,z points for elevation. The derived surface data can then be converted into raster data (GeoTIFFs). 20040817 through 20090821 Amar Nayegandhi Jacobs Technology, U.S. Geological Survey, CMGP, St. Petersburg, FL Computer Scientist mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 803-8747 (x3026) anayegandhi@usgs.gov M-F, 8:30-5:00 EST Metadata imported into ArcCatalog from XML file. 20091103 Xan Yates Jacobs Technology, U.S. Geological Survey, CMGP, St. Petersburg, FL Geologist/GIS Analyst/Metadata Specialist mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 803-8747 (x3086) M-F, 9:00-5:30 EST Tiling Index Raster Pixel 1683 882 1 row and column 1.000000 1.000000 meters Universal Transverse Mercator170.999600-81.0000000.000000500000.0000000.000000 North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222101 North American Vertical Datum of 1988 0.15 meters Explicit elevation coordinate included with horizontal coordinates Each pixel of the encoded GeoTIFF has an explicit elevation value associated with it. The GeoTIFF grid is encoded with a 1-meter resolution. The input parameters for the random consensus filter (RCF) were: grid cell size (buffer) = 7 meters x 7 meters; vertical tolerance (vertical width) = 50 centimeters. https://pubs.usgs.gov/of/2009/1078/ Jacobs Technology, U.S. Geological Survey, CMGP, St. Petersburg, FL Amar Nayegandhi Project Manager mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 803-8747 (x3026) M-F, 8:30-5:00 EST DS 482 This DVD publication was prepared by an agency of the United States Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. GeoTIFF GeoTIFF 2 DVD DVD Vary Contact U.S. Geological Survey. Vary Contact U.S. Geological Survey for details. 20040817 20040818 20091103 Xan Yates Jacobs Technology, U.S. Geological Survey, CMGP, St. Petersburg, FL Geologist/GIS Analyst/Metadata Specialist mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 803-8747 (x3086) M-F, 9:00-5:30 EST FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile