CRED Optical Validation Data in the Auau Channel, Hawaii, 2009 to Support Benthic Habitat Mapping

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Frequently anticipated questions:


What does this data set describe?

Title:
CRED Optical Validation Data in the Auau Channel, Hawaii, 2009 to Support Benthic Habitat Mapping
Abstract:
Optical validation data were collected using a Tethered Optical Assessment Device (TOAD), an underwater sled equipped with an underwater digital video camera and lights. Data were collected at the Main Hawaiian Islands, in the Auau Channel, Maui to support Benthic Habitat Mapping efforts during NOAA Ship Hi'ialakai cruise HA0905.
Supplemental_Information:
The Auau Channel, located between the islands of Maui and Lanai and also protected by Molokai to the north, and Kahoolawe to the south, is bounded by the latitudes 20.983 and 20.733 and the longitudes 156.633 and 156.858. Topography of the channel consists of solution basins and rims (ridges), sediment plains and reef pinnacles on the channel floor, which were subaerially exposed during late Quaternary lowstands of sea level. Holocene reef growth occurs as a thin veneer on topographic highs in the Channel. The Channel reaches depths of 140 m, however, the majority of the seafloor is between 55 m and 70 m deep. The Auau Channel has been documented to include abundant coral reefs at these depths, which are also known as mesophotic coral ecosystems. Optical validation data were collected using the Tethered Optical Assessment Device (TOAD), a sled equipped with underwater video camera and lights. These data are used to provide ground-truth validation for benthic habitat maps based on multibeam echosounder surveys and to gather addictional information regarding benthic and fish communities. Camera sled deployments were conducted at night, usually between 1800 and 600. The duration of each tow varied, but averaged about 1 hour of bottom time at a given location. The camera sled was deployed from lower arm of the starboard J-frame on the NOAA Ship Hi'ialakai. At each station the ship was positioned with the wind on the starboard side and drifted downwind; occasional light turns were applied to the ship's screws if necessary to reduce the ship's motion. The TOAD was lowered slowly to the bottom by a winch holding 360 m of cable and operated from a control station in the dry lab of the ship. The operator monitored a live video feed from the camera and began recording data on two video tape recorders. The operator continued to monitor the vehicle and provided commands to raise or lower it to keep the camera just above the bottom. Equipment Description: The TOAD sled body used for the data collection was constructed from a shortened Phantom ROV body with a tail piece added for stability. The frame has been extensively modified from its original configuration and was equipped with two Deep Sea Power and Light Multi SeaCam 2060 color video cameras. One camera was mounted to point at approximately a 45 degree angle toward the seafloor and was the primary data collection instrument. The second camera was aimed straight ahead and the signal from this camera was fed to a second video monitor to provide warning of underwater obstructions and for the survey of fish communites. The video signals from the sled were sent via coaxial conductors within a 315 m long and 19 mm diameter umbilical cable to a topside control unit. The cable between the sled and the surface included an internal strength member to support the sled frame.  The cable was paid out and recovered using a dedicated custom-built winch equipped with slip rings and powered by a 5 hp electric motor. The winch was controlled at the winch itself for sled deployments and recoveries. The rest of the time a remote controller located in the dry lab was used to enable the operator at the video console to adjust the sleds altitude. All TOAD surface components were located in the Dry Lab in an equipment rack on the after bulkhead. Illumination was provided by two 250 W DeepSea Power & Light Multi-SeaLite model 1050 underwater lights mounted on the sled frame. The lights were located on each side of the sled to provide the maximum possible horizontal distance from the camera. The sled was also equipped with a sonar altimeter to detect the height of the camera above the seafloor, a pair of parallel lasers to determine the size/scale of viewed objects, a compass to determine the sled heading and orientation, and a depth (pressure) sensor. Neither the altimeter nor the pressure transducer functioned reliably during this cruise. A Tcount cable counter recorded cable out values to locate the position of the camera sled from the ship. Name & address of person collecting data: John Rooney NOAA IRC NMFS/PIFSC/CRED 1845 WASP Blvd., Building 176 Honolulu, HI 96818 Data Files: Video data were recorded on two MiniDV tape recorders. The position of the camera sled was recorded using Hypack Max version 02.012a survey software. File naming convention: Each tow is given a name consisting of a 3-letter designator for the island area followed by a tow number. During HA0905 the consecutive numbers started at MAI09000. Video tape labels and paper log forms are annotated with the tow name. Data files recorded in Hypack software followed their CHS filename format consisting of the year, the Julian date, and the hour and minute in which the file was started. For example, a file collected on July 26, 2009 (Julian date 207) starting at time 1055 would be 2009_2071055. Time Correlation: All times are based on UTC. All clocks were manually synchronized prior to starting data collection; the clock in the video character generator that was used to annotate the video tape, the clock in the On Screen Display system, clocks in both MiniDV tape recorders, and in the computer running the Hypack Max software. These clocks were set to UTC at the beginning of each evening's operations.

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), 20100601, CRED Optical Validation Data in the Auau Channel, Hawaii, 2009 to Support Benthic Habitat Mapping.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -156.8243
    East_Bounding_Coordinate: -156.6797
    North_Bounding_Coordinate: 20.9371
    South_Bounding_Coordinate: 20.7766

  3. What does it look like?

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

    Beginning_Date: 24-Jul-2009
    Ending_Date: 02-Aug-2009
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: Video imagery, track line navigation files, and log sheets

  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?

  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 Island 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

    808 725-5360 (voice)
    808 725-5429 (FAX)
    nmfs.pic.credinfo@noaa.gov

    Contact_Instructions: e-mail preferred


Why was the data set created?

These data provide optical observations that will be used to provide information on the location and distribution of mesophotic corals and associated fish communities between 50 and 150 m depths. 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: 02-Aug-2009 (process 1 of 1)
    After a tow was completed the video tape data was reviewed by spot-checking the master and backup tape to verify that data were recorded. Raw data files recorded using Hypack Max software include time, horizontal position, and ship's heading information were copied from the acquisition computer to the data archive. Tow-specific metadata were recorded in the data archive in the same location as the raw data, in a spreadsheet that was then referred to in creating metadata records of each island where data were collected during the cruise. Raw data files were exported as comma-delimited text files which were then imported into ArcGIS v9.3 and saved as shapefiles. Spreadsheets containing location and time data were then used to classify benthic habitat for each tow using the Pacific Coral Reef Ecosystem Benthic Habitat Mapping classification scheme. Five points were classified at 30 second intervals and codes were inputted into spreadsheet. Spreadsheet was saved as dbase file, imported into ArcGIS v9.3, and saved as a shapefile. Percent scleractinian coral was column symbolized in Optical Validation maps with underlying fields of different substrates contained within the attribute table of the shapefile.

  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 camera sled position is estimated at plus or minus 80 meters. There are two primary sources of this error. The ship's positioning is based on GPS SPS, often called standalone or non-differential GPS positioning. SPS has a measured accuracy of under 5 meters. 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 the Tcount cable counter.

  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
    NOAA IRC
    Honolulu, HI 96818

    808 725-5360 (voice)
    808 725-5429 (FAX)
    nmfs.pic.credinfo@noaa.gov

    Contact_Instructions: e-mail preferred
  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
Last Reviewed: 19-Oct-2010
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: CRED Data Management Team
NOAA IRC
Honolulu, HI 96818

808 725-5360 (voice)
808 725-5429 (FAX)
nmfs.pic.credinfo@noaa.gov

Contact_Instructions: e-mail preferred
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)


Generated by mp version 2.9.13 on Thu Apr 24 10:39:09 2014