U.S. Geological Survey 2009 first remote-sensing image U.S. Geological Survey Data Series 464 St. Petersburg, FL U.S. Geological Survey A first-surface elevation map was produced cooperatively from remotely sensed, geographically referenced elevation measurements by the U.S. Geological Survey (USGS) and National Aeronautics and Space Administration (NASA). Elevation measurements were collected over the area using the NASA Airborne Topographic Mapper (ATM), a scanning lidar system that measures high-resolution topography of the land surface. The ATM system is deployed on a Twin Otter or P-3 Orion aircraft and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The purpose of this project is to produce highly detailed and accurate elevation maps of a portion of the Louisiana coastline within UTM zone 15 for natural-resource managers and research scientists. Raw lidar data are not in a format that is generally usable by resource managers and scientists. 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 Advanced Lidar Processing System (ALPS), a multi-tiered processing system developed by a USGS-NASA collaborative project. The zero crossing of the second derivative (that is, detection of local maxima) is used to detect "first surface" topography. Statistical filtering, known as the Random Consensus Filter (RCF), is used to remove false bottom returns and other outliers from the ATM 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, in press). These data are converted to the North American Datum of 1983 and the North American Vertical Datum of 1988 (using the GEOID03 model). The files are in the Quarter-Quad tiling format, and the exact tile location is contained in the filename at ########_fs, where ####### is the Quarter-Quad tile ID. The development of custom software for creating these data products has been supported by the USGS CMG Program's Decision Support for Coastal Parks, Sanctuaries, and Preserves Project. Processed data products are used by the USGS 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. 2001090720010910 ground condition Complete None planned 7.25269989473218 E+5 7.19047833571235 E+5 3.21711784366318 E+6 3.21007272286383 E+6 http://remotesensing.usgs.gov/ Airborne Lidar Processing System ALPS DEM Digital Elevation Model ATM Airborne Topographic Mapper laser altimetry lidar remote sensing topography http://nationalmap.gov/ Louisiana UTM zone 15 Gulf of Mexico http://lidar.cr.usgs.gov/ First surface http://www.esri.com/news/arcuser/1104/temporal.html 2001 None The U.S. Geological Survey and National Aeronautics and Space Administration request to be acknowledged as originators of the dataset in future products or derivative research. Xan Yates Jacobs Technology, U.S. Geological Survey, FISC GIS/Image Analyst/Metadata Specialist mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727-803-8747 (x3086) xyates@usgs.gov anayegandhi@usgs.gov M-F, 9:00-5:30 EST Acknowledgment of the U.S. Geological Survey, Florida Integrated 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. 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 2; ESRI ArcMap 9.2.2.1350 Nayegandhi, Amar, Brock, J.C., 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-centimeter nominal laser ranging accuracy, and vertical elevation accuracy of +/-15 centimeters for the topographic surface. Quality checks are built into the data-processing software. The files are in the Quarter-Quad tiling format, and the exact tile location is contained in the filename at ########_fs, where ####### is the Quarter-Quad tile ID. See the DOQQ naming convention document in the 'extras' directory. 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, optical water depth of greater than 1.5 Secchi disc depths, or the manual removal of lidar processing artifacts. Please note that this metadata file is a sample and therefore does not include valid bounding coordinates. Raw elevation measurements have been determined to be within 1 meter in horizontal accuracy. Elevations of the DEM are vertically consistent with the point elevation data, +/-15 centimeters. The data are collected using a Twin Otter aircraft. The NASA Airborne Topographic Mapper (ATM) laser scanner collects the data using a green raster scanning laser. The data are stored on hard drives and archived at the U.S. Geological Survey's FISC office in St. Petersburg, FL, 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 Advanced 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). 20011012-20090417 Amar Nayegandhi Jacobs Technology, U.S. Geological Survey, FISC, 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, 8:00-5:00 EST Metadata imported into ArcCatalog from XML file. 20090820 Xan Yates Jacobs Technology, U.S. Geological Survey, FISC, St. Petersburg, FL GIS/Image 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 xyates@usgs.gov Quater-Quadrangle Raster Pixel 271336931 row and column 4.000000 4.000000 meters Universal Transverse Mercator150.999600-93.0000000.000000500000.0000000.000000 North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222101 North American Vertical Datum of 1988 0.15 meters meters Explicit elevation coordinate included with horizontal coordinates This Digital Elevation Model is a GeoTIFF. It is raster data consisting of cells. Each cell has an elevation value associated with it. The input parameters for the Random Consensus Filter (RCF) were: grid cell size (buffer) = 8 meters by 8 meters; vertical tolerance (vertical width) = 20 centimeters. The variables measured by ATM are distance between aircraft and GPS satellites (meters), attitude information (roll, pitch, heading in degrees), scan angle (degrees), second of the epoch (seconds), and 1-nanosecond time-resolved return intensity waveform (digital counts). Z value is referenced to orthometric elevations derived from National Geodetic Survey Geoid Model, GEOID03. U.S. Geological Survey Project Manager Project Manager mailing address

600 4th Street South

St. Petersburg FL 33701 USA 727-803-8747 (x3026) M-F, 8:00-5:00 EST DS 464 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. TIFF 2 GeoTIFF DVD DVD Vary Contact U.S. Geological Survey Vary Contact U.S. Geological Survey for details. 2001090720010910 20090820 Xan Yates Jacobs Technology, U.S. Geological Survey, FISC, St. Petersburg, FL GIS/Image Analyst/Metadata Specialist mailing address

600 4th Street South

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