U.S. Geological Survey 2014 first raster digital data U.S. Geological Survey Data Series 885 St. Petersburg, FL U.S. Geological Survey https://dx.doi.org/10.3133/ds885 A digital elevation model for part of Barnegat Bay, New Jersey, pre-Hurricane Sandy (October 2012 hurricane), was produced from remotely sensed, geographically referenced elevation measurements by the U.S. Geological Survey. Elevation measurements were collected over the area using the second-generation Experimental Advanced Airborne Research Lidar, 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 55 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 0.5-1.6 meters. The nominal vertical elevation accuracy expressed as the root mean square error (RMSE) is 20 centimeters. A peak sampling rate of 15-30 kilohertz results in an extremely dense spatial elevation dataset. More than 100 kilometers of coastline can be surveyed easily within a 3- to 4-hour mission. When resultant 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 for part of Barnegat Bay, New Jersey, pre-Hurricane Sandy (October 2012 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 natural-resource managers and research 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 multitiered processing system developed originally by a USGS-NASA collaborative project. Specialized processing algorithms are used to convert raw waveform lidar data acquired by the EAARL-B 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 although first-surface data include vegetation, buildings, and other manmade structures, 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, whereas the trailing edge algorithm (that is, the algorithm searches for the location before 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 returns being the first and last significant measurable part 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-B 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 GEOID12A model). Each file contains data located in a 10-kilometer by 10-kilometer tile, where the upper-left bound can be ascertained quickly through the filename. The first 3 numbers in the filename represent the left-most UTM east bounding coordinate (e###000) in meters, the next 4 numbers represent the top-most UTM north bounding coordinate (n####000) in meters, and the last 2 numbers (##) represent the UTM zone in which the tile is located (for example, pre_e123_n4567_18). The development of custom software for creating these data products has been supported by the U.S. Geological Survey CMGP's Lidar for Science and Resource Management project. Processed data products are used by the U.S. Geological Survey CMGP'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. 20121018 20121022 20121023 20121026 ground condition Complete None planned ISO 19115 Topic Category elevation General Airborne Lidar Processing System ALPS Cessna 310 Digital Elevation Model DEM EAARL-B Experimental Advanced Airborne Research Lidar laser altimetry lidar remote sensing topography Global Change Master Science Directory LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION OCEAN > COASTAL PROCESSES > BARRIER ISLANDS OCEAN > COASTAL PROCESSES > BEACHES OCEAN > COASTAL PROCESSES > SHORELINE DISPLACEMENT DOI/USGS/CMG > COASTAL AND MARINE GEOLOGY, U.S. GEOLOGICAL SURVEY, U.S. DEPARTMENT OF INTERIOR GCMD Instrument LIDAR > LIGHT DETECTION AND RANGING Geographic Names Information System Ocean Barnegat Bay New Jersey Atlantic Ocean General Submerged General 2012 Pre-Hurricane Sandy None The U.S. Geological Survey requests to be acknowledged as originators of these data in future products or derivative research. Xan Fredericks Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL Lidar Validation and Processing Analyst mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 502-8086 727 502-8182 afredericks@usgs.gov M-F, 8:00-4:00 ET 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. 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 periods may be inaccurate because of 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 ArcCatalog 10.1.1.3143 5.8000 E+5 5.9000 E+5 4.43000 E+6 4.42000 E+6 -74.0638023418482 -73.9454116402289 40.0164153518598 39.9253251037677 Nayegandhi, A., Brock, J.C., and Wright, C.W. 2009 International Journal of Remote Sensing v. 30, no. 4, p. 861-878 The expected accuracy of the measured variables is as follows: attitude within 0.05 degree, 3 centimeters nominal ranging accuracy, and vertical elevation accuracy of 20 centimeters RMSE for the topographic surface. Quality checks are built into the data-processing software. Each file contains data located in a 10-kilometer by 10-kilometer tile where the upper-left bound can be ascertained quickly through the filename. The first 3 numbers in the filename represent the left-most UTM east bounding coordinate (e###000) in meters, the next 4 numbers represent the top-most UTM north bounding coordinate (n####000) in meters, and the last 2 numbers (##) represent the UTM zone in which the tile is located (for example, pre_e123_n4567_18). Several regions of the raster dataset are labeled as "No Data," which corresponds with a cell value of -32767 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. The presence of "No Data" values does not necessarily indicate an absence of land, but rather an absence of survey coverage or the presence of prolific vegetation that the laser is not able to penetrate to return bare-earth data. 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; however, a ground-control survey is not completed simultaneously with every lidar survey. Vertical accuracies may differ 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 EAARL-B 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 (20130318 - 20140106). Data are converted from units of time to x,y,z points for elevation and formatted into .las and .xyz files, and the derived surface data are converted into raster data (GeoTIFFs). 20121018 through 20140106 Xan Fredericks Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL Lidar Validation and Processing Analyst mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 502-8086 afredericks@usgs.gov M-F, 8:00-4:00 ET A bias correction of -16 centimeters (value determined from instrument calibrations) was applied to the point-cloud data using ALPS (20140822) to account for a change in configuration parameters. Data are formatted into .las and .xyz files, and the derived surface data are converted into raster data (GeoTIFFs). 20140822 Christine Kranenburg Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL Programmer/Analyst mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 502-8129 M-F, 7:30-3:30 ET ckranenburg@usgs.gov Metadata imported into ArcCatalog 10.1.1.3143 from XML file. 20140127 Xan Fredericks Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL Lidar Validation and Processing Analyst mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 502-8086 M-F, 8:00-4:00 ET afredericks@usgs.gov Tiling Index Raster Pixel row and column 2.500000 2.500000 meters Universal Transverse Mercator 18 0.999600 -75.000000 0.000000 500000.000000 0.000000 North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.25722210100002 North American Vertical Datum of 1988 0.20 meters Explicit elevation coordinate included with horizontal coordinates The input parameters for the random consensus filter (RCF) were: grid cell size (buffer) = 1500 centimeters x 1500 centimeters; vertical tolerance (vertical width) = 40 centimeters. https://pubs.usgs.gov/of/2009/1078/ U.S. Geological Survey Xan Fredericks Lidar Validation and Processing Analyst mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 502-8086 M-F, 8:00-4:00 ET DS 885 Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The USGS shall not be held liable for improper or incorrect use of the data describe or contained herein. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. GeoTIFF GeoTIFF 2 https://dx.doi.org/10.3133/ds885 None Contact U.S. Geological Survey. Vary Contact U.S. Geological Survey for details. 20121018 20121022 20121023 20121026 20140127 Xan Fredericks Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL Lidar Validation and Processing Analyst mailing and physical address

600 4th Street South

St. Petersburg FL 33701 USA 727 502-8086 M-F, 8:00-4:00 ET afredericks@usgs.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time http://www.esri.com/metadata/esriprof80.html Esri Metadata Profile