2020 NOAA NGS Topobathy Lidar: Guam

Description

Woolpert, Inc. was contracted to acquire and process topographic-bathymetric lidar for the islands of Anatahan, Alamagan, Guguan, and Sarigan in response to Hurricane Yutu for Quantum Spatial, Inc. (QSI). Woolpert collected lidar using their Leica HawkEye 4X (HE4X) topo-bathy lidar sensor that consists of a Chiroptera 4X (CH4X) sensor, with an additional Leica 40kHz deep bathymetric channel to provide high density topo lidar. The HE4X is a latest generation topographic and bathymetric lidar sensor. The system provides denser data than previous traditional bathymetric lidar systems. It is unique in its ability to acquire bathymetric lidar, topographic lidar and 4-band digital camera imagery simultaneously. The HE4X provided 300 kHz topographic data, an effective 140 kHz shallow bathymetric data and 40 kHz deep bathymetric data. 4-band 80 MP digital camera imagery was also collected simultaneously with the sensor’s RCD-30 camera. The bathymetric and topographic lasers are independent and do not share an optical chain or receivers, so they are optimized for their specific function. As with any bathymetric lidar, maximum depth penetration is a function of water clarity and seabed reflectivity. The HE4X is designed to penetrate to 3 times the secchi depth. This is also represented as Dmax = 4/K, where K is the diffuse attenuation coefficient, and assuming K is between 0.1 and 0.3, a normal sea state and 15% seabed reflectance. Both the topographic and bathymetric sub-systems use a palmer scanner to produce an elliptical scan pattern of laser points with a degree of incidence ranging from +/-14 degrees (front and back) to +/-20 degrees (sides), providing a 40 degrees field of view. This has the benefit of providing multiple look angles on a single pass and helps to eliminate shadowing effects. This can be of particular use in urban areas, where all sides of a building are illuminated, or for bathymetric features such as the sides of narrow water channels or features on the seafloor such as smaller objects and wrecks. It also assists with penetration in the surf zone where the back scan passes the same ground location a couple of seconds after the front scan, allowing the areas of whitewater to shift. All topo lidar data for this project were collected simultaneous to meet United States Geological Survey, Quality Level 1 (USGS QL1) with a minimum of 8 pts per square meter at an accuracy of 10cm RMSEz. A minimum of 2 points per square meter were acquired for bathymetric lidar data. For practical purposes the survey area was divided into survey blocks in each island, allowing acquisition to be conducted in the most efficient and consistent manner possible. The data includes topobathy data in an LAS 1.4 format file along with associated bare earth digital elevation models (DEM). The dataset was derived from topobathymetric data in a LAS format 1.4, point data record format 6, with the following classifications in accordance with project specifications and the American Society for Photogrammetry and Remote Sensing (ASPRS) classification standards: 1 - unclassified 2 - ground 7 - noise 40 - bathymetric bottom or submerged topography 41 - water surface 42 - derived water surface 43 - manmade submerged feature 45 - water column 1 Overlap - edge clip 1 Withheld - bathy land User data values differentiates between NIR and green lasers. A value of 3 indicates the point is from the NIR laser, a value of 0 indicates the green shallow laser, and 1 indicates the green deep laser. This dataset is the Guam ellipsoid point cloud data set.

Resources

Name Format Description Link
0 The Data Access Viewer (DAV) allows a user to search for and download elevation, imagery, and land cover data for the coastal U.S. and its territories. The data, hosted by the NOAA Office for Coastal Management, can be customized and requested for free download through a checkout interface. An email provides a link to the customized data, while the original data set is available through a link within the viewer. https://coast.noaa.gov/dataviewer/
0 NOAA Office for Coastal Management Home Page https://coast.noaa.gov
0 Global Change Master Directory (GCMD). 2024. GCMD Keywords, Version 19. Greenbelt, MD: Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA). URL (GCMD Keyword Forum Page): https://forum.earthdata.nasa.gov/app.php/tag/GCMD+Keywords https://forum.earthdata.nasa.gov/app.php/tag/GCMD%2BKeywords
33 Topobathymetric Lidar Data Report https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/9322/supplemental/NOAA_Typhoon_Yutu_Topobathymetric_Lidar_Data_Report.pdf
0 View the complete metadata record on InPort for more information about this dataset. https://www.fisheries.noaa.gov/inport/item/64811
0 Website listed for National Geodetic Survey https://geodesy.noaa.gov/
0 Create custom data files by choosing data area, product type, map projection, file format, datum, etc. A new metadata will be produced to reflect your request using this record as a base. Change to an orthometric vertical datum is one of the many options. https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9322
0 Bulk download of data files in LAZ format, geographic coordinates, orthometric heights. Note that the vertical datum (hence elevations) of the files here are different than described in this document. They will be in an orthometric datum. https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/9322/
33 NOAA Data Management Plan for this record on InPort. https://www.fisheries.noaa.gov/inportserve/waf/noaa/nos/ngs/dmp/pdf/64811.pdf

Tags

  • vertical location
  • topography
  • national geodetic survey
  • land surface
  • terrain elevation
  • national ocean service
  • doc/noaa/nos/ngs
  • bathymetry
  • oceans
  • noaa
  • airplane
  • coastal elevation
  • u.s. department of commerce
  • erosion
  • earth science
  • bathymetry/seafloor topography
  • ngs lidar
  • coastal bathymetry
  • light detection and ranging
  • sea floor
  • lidar
  • coastal processes
  • beach

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