Test of the Capability of Laser Line Scan Technology to Support Benthic Habitat Mapping in Coral Reef Ecosystems, Maui Island, November 2006

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What does this data set describe?

Title:
Test of the Capability of Laser Line Scan Technology to Support Benthic Habitat Mapping in Coral Reef Ecosystems, Maui Island, November 2006
Abstract:
The utility of Laser Line Scan (LLS) Technology for optical validation of benthic habitat map data from coral reef ecosystems was tested with a deployment of a Northrop Grumman SM-2000 Laser Line Scan (LLS) system, which is owned and operated by Science Applications International Corporation (SAIC). Data were collected between the islands of Lanai, Molokai, and Maui in the Main Hawaiian Islands during a dedicated cruise aboard the NOAA Ship Hi'ialakai in November 2006.
Supplemental_Information:
The area between the islands of Maui County is a heavily transited and utilized waterway. Vessels engaged in inter-island commerce, recreational and commercial fishing, and a host of recreational whale watchers, sailors, divers, surfers, beachgoers and others take advantage of them every day, making them an important economic, and somewhat stressed, environmental resource. The area features a wide shelf top with depths ranging from 50 - 80 m that is relatively sheltered from large swell by the surrounding islands, but is often exposed to strong currents. During the last glacial maximum ca. 21,000 years ago, sea level was estimated to range from 130-135 m lower than it is today, creating a single large island called "Maui Nui". The insular shelf between the modern Maui County islands was above sea level for thousands of years, exposing this limestone structure to karst processes. Subsequent sea level rise and Holocene reef growth accentuated the karst topography resulting in the solution basins and rims, and reef pinnacles seen in the modern bathymetry. The combination of wave sheltering and high flow regimes led to the development of the largest known black coral beds in Hawaii, and well-developed hermatypic coral reefs that may extend deeper than those recently reported from Pulley Ridge off Florida (Jarrett et al., 2005). At the same time, the complex bathymetry divides the area into a number of separate pinnacles, ridge lines, and solution basins that may harbor their own unique suite of environmental parameters and biological communities. In addition to the extensive and already discovered rich reef and snapper communities, it has been suggested that the convoluted surface of the shelf may provide habitat and serve as a refugia for other marine organisms. Populations that have been severely and negatively affected in shallower waters closer to shore by polluted runoff from land, heavy fishing and spearfishing pressure, and other anthropogenic impacts, may be sustained by the unique and more isolated features of this area. It is important to understand the environmental significance of this shelf and to map particularly fragile or important areas so that they can be managed and protected appropriately. It should be noted that the rugged nature of the seafloor would make deployment of photographic camera sleds at 1-5 m above bottom a high risk operation and damage to the tow body would be likely. Thus, the ability to fly the laser line scan equipment at higher altitudes above bottom makes use of this sensor on the Maui Nui shelf very desirable. Laser line scan data were collected during cruise HI-06-14 aboard the NOAA Ship Hi'ialakai. The Northrop Grumman SM-2000 Laser Line Scan (LLS) system, which is owned and operated by Science Applications International Corporation (SAIC), was leased for this test. The LLS system was towed for about 24 hours over the seafloor in the channels between the islands of Maui, Lanai, and Molokai. The altitude of the LLS instrument was set at 8 m above the seafloor for the duration of the deployment. During testing the LLS towfish struck and underwater ledge resulting in the loss of the instrument.

Equipment Description - During a 3-day mobilization, SAIC and ships personnel, aided by commercial welders, mounted a towing winch on the centerline, at the forward edge, of the Hi'ialakai's fantail. A large-diameter sheave was hung from the center of the A-frame at the ship's stern, with the towcable from a dedicated tow winch run over it. Six consoles were set up along the aft bulkhead of the Hi'ialakai's dry lab to operate the tow vehicle and winch, provide navigation information, operate an IXSEA GAPS acoustic ultrashort baseline navigation system (USBL) used to track the position of the tow vehicle, and provide data processing capabilities. A hinged pole mount for the USBL transducer was welded to the port side of the Hi'ialakai on the after end of the 01 deck. The mount was designed to enable the pole to be lifted out of the water during transit periods. Once the ship was in position to begin laser line scan surveying, the pole was lowered into a vertical position and held in place with guy wires. The LLS instrument was mounted on a Focus 1500 remote operated tow vehicle (ROTV) which provides a stable platform that can be maneuvered along survey tracklines and provides a coordinated uplink of sensor and instrumentation data over a fiber optic tow cable. The altitude of the focus ROTV was tracked using a Klein sidescan system.

Name & address of person collecting data John Rooney NOAA IRC NMFS/PIFSC/CRED 1845 WASP Blvd., Building 176 Honolulu, HI 96818

Data Files - Laser Line Scan data as well as information from peripheral equipment such as the IXSEA Gaps system were recorded on two separate computers and an external hard drive. The LLS data were recorded in 168 different files in a proprietary "OIC" format and averaged 0.53 Gb per file. OIC file names start with a designation for the survey line number, followed by the Julian year, day and time, with each of these separated by periods, and followed by the ".oic" filename extension. All times are based on UTC.

Resource Description: Digital video imagery that is geo-referenced to navigation files.

  1. How should this data set be cited?

    Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), 200705, Test of the Capability of Laser Line Scan Technology to Support Benthic Habitat Mapping in Coral Reef Ecosystems, Maui Island, November 2006.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -156.90833
    East_Bounding_Coordinate: -156.65833
    North_Bounding_Coordinate: 21.08000
    South_Bounding_Coordinate: 20.96333

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 08-Nov-2006
    Ending_Date: 10-Nov-2006
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: raster digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 5
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -159.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000

      Planar coordinates are encoded using Row and Column
      Abscissae (x-coordinates) are specified to the nearest 0.02
      Ordinates (y-coordinates) are specified to the nearest 0.02
      Planar coordinates are specified in meters

      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.

  7. How does the data set describe geographic features?


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    Pacific Islands Benthic Habitat Mapping Center, Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), NOAA

  3. To whom should users address questions about the data?

    Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
    Attn: John Rooney
    NOAA IRC
    Honolulu, HI 96818
    USA

    808 725-5360 (voice)
    john.rooney@noaa.gov


Why was the data set created?

Data collected during this test deployment of a Laser Line Scan system will be processed and analyzed to gain an understanding of how useful this technology is for mapping of benthic habitats in coral reef ecosystems. Refer to supplemental information for description of instrument and survey.


How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: 15-Jul-2007 (process 1 of 1)
    Data files were set to automatically be terminated and new ones generated every 10 minutes during periods of LLS data collection. File names were changed on occasion by operators who change equipment settings or noticed problems occurring or being corrected in raw LLS imagery that was being displayed in near real time. Several different processing streams were used with portions of the data. GeoDAS and CleanSweep software were developed by Ocean Imaging Consultants for SAIC specifically to process and georeference imagery from the LLS instrument. These software packages will be used to process most of the imagery. Dr. Yuri Rzhanov of the University of New Hampshire Center for Coastal and Ocean Mapping, and Roger Davis of the Hawaii Mapping Research Group at the University of Hawaii each developed their own suite of processing programs based on existing scripts and utilities used by their respective institutions to process Multibeam echosounder data. In all cases, the resulting data are georeference gras-scale imagery, presented as geotiff format files.

  3. What similar or related data should the user be aware of?


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

    The horizontal position accuracy for the laser line scan data is estimated to be + or - 10 meters. There are two primary sources of this error. The ship's positioning is based on DGPS, or differential GPS positioning. The position of the GPS antenna is referenced to the ship's granite block. The second and larger primary source of error is uncertainty associated with the sled's position as reported by IXSEA Gaps acoustic tracking system, which is also referenced to the granite block.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Complete

  5. How consistent are the relationships among the observations, including topology?

    Unspecified


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints:
Please acknowledge the NOAA Coral Reef Ecosystem Division, Pacific Islands Fisheries Science Center as the source of this information.

  1. Who distributes the data set? (Distributor 1 of 1)

    Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
    Attn: John Rooney
    Coastal Geomorphologist
    NOAA IRC
    Honolulu, Hawaii 96818
    USA

    808 725-5360 (voice)
    john.rooney@noaa.gov

  2. What's the catalog number I need to order this data set?

    Offline Data

  3. What legal disclaimers am I supposed to read?

    These data are not to be used for navigational purposes. NOAA makes no warranty regarding these data, expressed or implied, nor does the fact of distribution constitute such a warranty. NOAA cannot assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 12-Mar-2014
Metadata author:
Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)
Attn: Dr. John Rooney
Coastal Geomorphologist
NOAA IRC
Honolulu, Hawaii 96818
USA

808 725-5360 (voice)
john.rooney@noaa.gov

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


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