remote-sensing image U.S. Geological Survey 2010 U.S. Geological Survey Data Series 556 St. Petersburg, FL U.S. Geological Survey first ASCII xyz point cloud data were produced from remotely sensed, geographically referenced elevation measurements cooperatively by the U.S. Geological Survey (USGS), the National Aeronautics and Space Administration (NASA), and the National Park Service (NPS). Elevation measurements were collected over the area using the 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, resulting in a laser swath of approximately 240 meters with an average point spacing of 2-3 meters. The EAARL, developed originally 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 easily surveyed 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 highly detailed and accurate digital elevation maps of a portion of the Mississippi and Alabama barrier islands, post-Hurricane Gustav (September 2008 hurricane), 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 terms first surface and bare earth refer to the digital elevation data of the terrain, but while the first-surface data include vegetation, buildings, and other manmade structures, the bare-earth data do not. The zero crossing of the second derivative (that is, detection of stationary points) is used to detect the first return, resulting in "first surface" topography, while the trailing edge algorithm (that is, 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" (the first and last return being the first and last significant measurable portion of the return pulse). 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 GEOID09 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 (ex. fs_e123_n4567_18). 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 Science and Management 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. 20080908 ground condition Complete None planned 3.5400 E+5 3.5600 E+5 3.34600 E+6 3.34400 E+6 ISO 19115 Topic Category elevation 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 General Mississippi Alabama Barrier Islands General First Surface General 2008 Post-Hurricane Gustav None The U.S. Geological Survey and National Park Service to be acknowledged as originators of this data in future products or derivative research. Amar Nayegandhi Jacobs Technology, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL Remote Sensing Specialist/Project Manager mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 803-8747 (x3026) 727-803-2031 M-F, 9:00-5:00 EST anayegandhi@usgs.gov Acknowledgment of the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, 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 by users of this data. Sharing 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. Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.2.1350 UnclassifiedUnclassifiedNone These point-cloud data may appear sparse or nonexistent in some areas, which may be a result of manual removal during the editing process or from lack of survey coverage. The expected accuracy of the measured variables is as follows: attitude within 0.07 degree, 3-centimeter nominal ranging accuracy, and vertical elevation accuracy of +/-15 centimeters for the topographic surface. Quality checks are built into the data-processing software. Raw elevation measurements have been determined to be within 1 meter in horizontal accuracy. Typical vertical elevation accuracies for these data are consistent with the point elevation data, +/-15 centimeters. However, a ground-control survey is not conducted simultaneously with every lidar survey. Vertical accuracies may vary based on the type of terrain and the accuracy of the GPS and aircraft-attitude measurements. The data were collected using a Cessna 310 aircraft. The Experimental Advanced Airborne Research Lidar (EAARL) laser scanner collects the data using a green-wavelength (532-nanometer) 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. The navigational data are processed and then, along with the raw data, are downloaded into ALPS, or the Airborne Lidar Processing System (20100309 - 20100712). Data are converted from units of time to x,y,z points for elevation and formatted into .las and .xyz files. The derived surface data can then also be converted into raster data (GeoTIFFs). 20080908 through 20101101 Jamie M. Bonisteel-Cormier Jacobs Technology, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL Lidar Analyst mailing and physical address

600 4th Street South

Saint Petersburg FL 33701 USA 727-803-8747 (x3124) M-F, 8:30-4:30 EST jcormier@usgs.gov Metadata imported into ArcCatalog from XML file. 20101101 Xan Fredericks Jacobs Technology, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL GIS Analyst/Metadata Specialist mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727-803-8747 (x3086) M-F, 8:00-4:00 EST afredericks@usgs.gov 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 (ex. fs_e123_n4567_16). Point row and column 1.000000 1.000000 meters Universal Transverse Mercator 0.999600 -87.0000 0 500000.0000 0 16 North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.25722210100002 North American Vertical Datum of 1988 0.15 meters Explicit elevation coordinate included with horizontal coordinates https://pubs.usgs.gov/of/2009/1078/ The input parameters for the Random Consensus Filter (RCF) were: grid cell size (buffer) = 5 meters x 5 meters; vertical tolerance (vertical width) = 400 centimeters. *.xyz The "*" represnets the file name. The file is .xyz ASCII space-delimited. Internally devised to maintain naming consistency. X UTM easting in meters NAVD 88 varying value range Y UTM northing in meters NAVD 88 varying value range Z Altitude in meters NAVD 88 varying value range mailing and physical address

600 4th Street South

Saint Petersburg FL 33701 USA 727 803-8747 U.S. Geological Survey Project Manager Project Manager M-F, 8:00-5:00 EST 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 herin 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. Vary ASCII XYZ 1 DVD DVD Contact U.S. Geological Survey Vary Contact U.S. Geological Survey for details. 20080908 DS 556 20110103 Xan Fredericks Jacobs Technology, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL GIS Analyst/Metadata Specialist mailing and physical address St. Petersburg FL 33701

600 4th Street South

USA 727 803-8747 (x3086) M-F, 8:00-4:00 EST afredericks@usgs.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time -8.851730157919636 E+1 -8.84962493616520 E+1 3.02370495874983 E+1 3.02187683285217 E+1