Identification_Information: Citation: Citation_Information: Originator: U.S. Geological Survey Publication_Date: 2009 Publication_Time: Title: EAARL Coastal Topography--Assateague Island National Seashore, 2008: Bare Earth Edition: first Geospatial_Data_Presentation_Form: remote-sensing image Series_Information: Series_Name: U.S. Geological Survey Data Series Issue_Identification: 447 Publication_Information: Publication_Place: St. Petersburg, FL Publisher: U.S. Geological Survey Description: Abstract: A bare-earth elevation map (also known as a Digital Elevation Model, or DEM) of the Assateague Island National Seashore in Virginia and Maryland was produced from remotely sensed, geographically referenced elevation measurements cooperatively by the U.S. Geological Survey (USGS), the National Park Service (NPS), 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 land managers. Purpose: The purpose of this project was to produce a highly detailed and accurate bare-earth digital elevation map of the Assateague Island National Seashore in Virginia and Maryland for use as a management tool and to make these data available to natural-resource managers and research scientists. Supplemental_Information: 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 (that is, detection of local maxima) is used to detect "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". 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 (ex. be_e123_n4567_18). The development of custom software for creating these data products has been supported by the U.S. Geoloigcal Survey CMG Program's Decision Support for Coastal Parks, Sanctuaries, and Preserves Project. Processed data products are used by the U.S. Geoloigcal 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. Time_Period_of_Content: Time_Period_Information: Multiple_Dates/Times: Single_Date/Time: Calendar_Date: 20080324 Single_Date/Time: Calendar_Date: 20080325 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: 0 East_Bounding_Coordinate: 0 North_Bounding_Coordinate: 0 South_Bounding_Coordinate: 0 Keywords: Theme: Theme_Keyword_Thesaurus: http://remotesensing.usgs.gov/ Theme_Keyword: Airborne Lidar Processing System Theme_Keyword: ALPS Theme_Keyword: Digital Elevation Model Theme_Keyword: DEM Theme_Keyword: EAARL Theme_Keyword: Experimental Advanced Airborne Research Lidar Theme_Keyword: laser altimetry Theme_Keyword: lidar Theme_Keyword: remote sensing Theme_Keyword: topography Place: Place_Keyword_Thesaurus: http://nationalmap.gov/ Place_Keyword: Assateague Island National Seashore Place_Keyword: Virginia Place_Keyword: Maryland Stratum: Stratum_Keyword_Thesaurus: http://lidar.cr.usgs.gov/ Stratum_Keyword: Bare Earth Temporal: Temporal_Keyword_Thesaurus: http://www.esri.com/news/arcuser/1104/temporal.html Temporal_Keyword: 2008 Access_Constraints: None Use_Constraints: The U.S. Geological Survey, National Park Service, and National Aeronautics and Space Administration request to be acknowledged as originators of this data in future products or derivative research. Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Amar Nayegandhi Contact_Organization: Jacobs Technology, U.S. Geological Survey, FISC, St. Petersburg, FL Contact_Position: Computer Scientist Contact_Address: Address_Type: mailing and physical address Address: 600 4th Street South City: St. Petersburg State_or_Province: FL Postal_Code: 33701 Country: USA Contact_Voice_Telephone: 727 803-8747 (x3026) Contact_Facsimile_Telephone: 727-803-2031 Contact_Electronic_Mail_Address: anayegandhi@usgs.gov Hours_of_Service: M-F, 8:00-5:00 EST Data_Set_Credit: 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 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. Security_Information: Security_Classification_System: Unclassified Security_Classification: Unclassified Security_Handling_Description: None Native_Data_Set_Environment: Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.2.1350 Cross_Reference: Citation_Information: Originator: Nayegandhi, Amar, Brock, J.C., and Wright, C.W. Publication_Date: 2009 Title: Small footprint, waveform-resolving lidar estimation of submerged and subcanopy topography in coastal environments Series_Information: Series_Name: International Journal of Remote Sensing Issue_Identification: 30(4), p. 861-878 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: 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. Logical_Consistency_Report: 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. be_e123_n4567_18). Completeness_Report: 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. This metadata file is for example only and does not provide bounding coordinates for that reason. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Raw elevation measurements have been determined to be within 1 meter in horizontal accuracy. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: Elevations are vertically consistent with the point elevation data, +/-15 centimeters. Lineage: Process_Step: Process_Description: 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, 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 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). Process_Date: 20080324 through 20080915 Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Amar Nayegandhi Contact_Organization: Jacobs Technology, U.S. Geological Survey, FISC, St. Petersburg, FL Contact_Position: Computer Scientist Contact_Address: Address_Type: mailing and physical address Address: 600 4th Street South City: St. Petersburg State_or_Province: FL Postal_Code: 33701 Country: USA Contact_Voice_Telephone: 727-803-8747 (x3026) Contact_Electronic_Mail_Address: anayegandhi@usgs.gov Hours_of_Service: M-F, 8:00-5:00 EST Process_Step: Process_Description: Metadata imported into ArcCatalog from XML file. Process_Date: 20080915 Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Xan Yates Contact_Organization: Jacobs Technology, U.S. Geological Survey, FISC, St. Petersburg, FL Contact_Position: GIS/Image Analyst/Metadata Specialist Contact_Address: Address_Type: mailing and physical address Address: 600 4th Street South City: St. Petersburg State_or_Province: FL Postal_Code: 33701 Country: USA Contact_Voice_Telephone: 727-803-8747 (x3086) Hours_of_Service: M-F, 9:00-5:30 EST Spatial_Data_Organization_Information: Indirect_Spatial_Reference: Tiling Index Direct_Spatial_Reference_Method: Raster Raster_Object_Information: Raster_Object_Type: Pixel Row_Count: 2001 Column_Count: 2001 Vertical_Count: 1 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Grid_Coordinate_System: Grid_Coordinate_System_Name: Universal Transverse Mercator Universal_Transverse_Mercator: UTM_Zone_Number: 18 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.999600 Longitude_of_Central_Meridian: -75.000000 Latitude_of_Projection_Origin: 0 False_Easting: 500000.000000 False_Northing: 0 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: row and column Coordinate_Representation: Abscissa_Resolution: 1.000000 Ordinate_Resolution: 1.000000 Planar_Distance_Units: meters Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: Geodetic Reference System 80 Semi-major_Axis: 6378137.000000 Denominator_of_Flattening_Ratio: 298.257222 Vertical_Coordinate_System_Definition: Altitude_System_Definition: Altitude_Datum_Name: North American Vertical Datum of 1988 Altitude_Resolution: 0.15 meters Altitude_Distance_Units: meters Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates Entity_and_Attribute_Information: Overview_Description: Entity_and_Attribute_Overview: 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) = 6 meters x 6 meters; vertical tolerance (vertical width) = 50 centimeters. Entity_and_Attribute_Detail_Citation: The variables measured by EAARL 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. Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Person: Project Manager Contact_Position: Project Manager Contact_Address: Address_Type: mailing and physical address Address: 600 4th Street South City: St. Petersburg State_or_Province: FL Postal_Code: 33701 Country: USA Contact_Voice_Telephone: 727-803-8747 (x3026) Hours_of_Service: M-F, 8:00-5:00 EST Resource_Description: DS 447 Distribution_Liability: 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. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: GeoTIFF Format_Version_Number: 2 Format_Specification: GeoTIFF Digital_Transfer_Option: Offline_Option: Offline_Media: DVD Recording_Format: DVD Fees: Vary Ordering_Instructions: Contact U.S. Geological Survey. Turnaround: Vary Custom_Order_Process: Contact U.S. Geological Survey for details. Available_Time_Period: Time_Period_Information: Multiple_Dates/Times: Single_Date/Time: Calendar_Date: 20080324 Single_Date/Time: Calendar_Date: 20080325 Metadata_Reference_Information: Metadata_Date: 20080915 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Xan Yates Contact_Organization: Jacobs Technology, U.S. Geological Survey, FISC, St. Petersburg, FL Contact_Position: GIS/Image Analyst/Metadata Specialist Contact_Address: Address_Type: mailing and physical address Address: 600 4th Street South City: St. Petersburg State_or_Province: FL Postal_Code: 33701 Country: USA Contact_Voice_Telephone: 727-803-8747 (x3086) Hours_of_Service: M-F, 9:00-5:30 EST Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: local time Metadata_Extensions: Online_Linkage: http://www.esri.com/metadata/esriprof80.html Profile_Name: ESRI Metadata Profile