CRED Optical Validation Data at the island of Ta'u in American Samoa, 2012 to support Benthic Habitat Mapping (TOAD)

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Frequently anticipated questions:


What does this data set describe?

Title:
CRED Optical Validation Data at the island of Ta'u in American Samoa, 2012 to support Benthic Habitat Mapping (TOAD)
Abstract:
Optical validation data were collected using the Tethered Optical Assessment Device (TOAD), a sled equipped with underwater video camera, still camera and lights. Camera sled deployments were conducted during the day, from the contracted vessel Bonavista II. Data were collected in American Samoa, around the island of Ta'u to support Benthic Habitat Mapping efforts from November 6-9, 2012.
Supplemental_Information:
Ta'u Island is part of the Manu'a Island group in American Samoa, situated approximately 150 km northeast of Tutuila and 20 km east of Olosega Island. Ta'u is an extremely steep, heavily vegetated high volcanic island with almost no surrounding banks; the seafloor surrounding Ta'u drops steeply to abyssal depths. Centered at 14.23 degrees S, 169.50 degrees W, Ta'u has very little human settlement.

Optical validation data were collected using the Tethered Optical Assessment Device (TOAD), a sled equipped with underwater video and still camera and lights. These data are used to provide ground-truth validation for benthic habitat maps based on multibeam echosounder surveys. Camera sled deployments were conducted during the day. The duration of each tow varied but averaged about 20 minutes of bottom time at a given location. The camera sled was deployed from a pot-hauler, mounted on the starboard aft of the vessel. The camera sled was lowered slowly to the seafloor by paying out cable, and once close to the seafloor, an altitude of 1-2 m was maintained by making adjustments on the length of cable out, using a remote pot-hauler switch, which allowed the operator to monitor a live video feed of the seafloor during operations. A second operator monitored the live video feed, and recorded real-time scientific observations, as well as any comments upon the operation, on a paper logsheet.

Equipment Description: The TOAD sled consisted of a modified Phantom ROV body with a tail piece added for stability. It was equipped with a Deep Sea Power and Light Multi SeaCam 2060 color video camera, oriented approximately 45 degrees to the seafloor to provide a view of the seafloor as well as some view of upcoming obstacles. The sled was also fitted with a downward facing digital still camera (Ocean Imaging System DSC12000, consisting of Nikon D90 dSLR with Nikkor 20mm F/2.8 lens), and two 50 W DeepSea Power and Light LED lights (one to illuminate the video and one the still camera). Scaling of the digital still photographs was provided by a pair of Deep Sea Power and Light SeaLaster 100 parallel lasers, mounted 10 cm apart. The sled was also fitted with a Tritech PA200 altimeter, and an electronics bottle containing a compass, and depth sensor. Power to the sled, and video and data feed from the sled was conducted via a 16mm, 150 m long coaxial cable, connected to a topside control unit. An on-screen display unit was used to overlay time, date, depth and altitude onto the video footage.

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 to miniDV tapes, and then backed up to DVD. Still images were saved to the camera's SD card and then backed up to external hard drive. Hypack 2012 hydrographic software was used to record time, vessel GPS position, camera sled altitude and depth, and length of cable out (entered manually). During deployments instantaneous layback calculations were performed by Hypack, using these data, and including the measured xyz offset between the vessel GPS antenna and the pot-hauler.

File naming convention: Each tow is given a name consisting of a three-letter designator for the island area, followed by a two-digit year and a three-digit tow number, which increments by one for each new tow around that island. For example, during SB1216 (the 16th cruise in the calendar year 2012) the first tow was called TAU12001. For subsequent cruises in the same year, the tow numbers will increment by 100, so the first tow on the next cruise to Ta'u in 2012 will be tow number TAU12100. Video tape labels and paper log forms are also annotated with the tow name; if more than one tape is required for a tow, consecutive letters are added to the end of the tow number (TAU12100a, TAU12100b, TAU12100c...). Navigation files generated by Hypack Max follow the Hypack CHS filename format consisting of the year, the first two letters of the platform name, the Julian date, and the hour and minute in which the file was started, followed by the extension .raw. For example, a file begun at 1935 on Dec. 10, 2004 (Julian date 345) aboard the Carolinian would be 2004CA3451935.raw.

Time Correlation: All clocks were synchronized to UTC at the beginning of each day's operations. Two clocks were manually synchronized to GPS-derived times: the acquisition computer clock and the internal clock of the OSD-79 on-screen display unit.

Resource Description: Digital video and still 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), 20121215, CRED Optical Validation Data at the island of Ta'u in American Samoa, 2012 to support Benthic Habitat Mapping (TOAD).

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -169.57
    East_Bounding_Coordinate: -169.40
    North_Bounding_Coordinate: -14.19
    South_Bounding_Coordinate: -14.30

  3. What does it look like?

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

    Beginning_Date: 06-Nov-2012
    Ending_Date: 09-Nov-2012
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form:
    Photo and 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?

    Entity_and_Attribute_Overview: none
    Entity_and_Attribute_Detail_Citation: none


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)
    NOAA IRC
    Honolulu, HI 96818
    USA

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

    Contact_Instructions: e-mail preferred


Why was the data set created?

These data provide optical observations that will be correlated with bathymetry and acoustic backscatter imagery to develop a benthic habitat map of Ta'u. 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: 09-Nov-2012 (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 include time, horizontal position, depth information and altitude, and were copied from the acquisition computer to the data archive. During this cruise it was possible to export sled altitude from Hypack. 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 from Hypack as comma-delimited text files, and following additional processing were imported into a custom Access Database for imagery classification. The benthic habitat for each tow was classified using the PIBHMC_tow classification scheme. Five points were classified at 30 second intervals along the video and codes were inputted directly into the TOAD database. The classified results were then imported into ArcGIS v10.1, and then saved as a shapefile. Percent scleractinian coral was color-symbolized in optical validation maps. Additional attributes include metadata for each point, and the full results of the benthic classification. For more information on classificiation methods, refer to the PIBHMC website: <ftp://ftp.soest.hawaii.edu/pibhmc/website/webdocs/documentation/Optical-Proc-Overview.pdf> For more information on the classification scheme,refer to the PIBHMC website: <ftp://ftp.soest.hawaii.edu/pibhmc/website/webdocs/documentation/Benth-Habitat-Class-Codes.htm>

  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?

    Hypack 2012 includes a window for manual entry of the length of camera sled cable paid out, a utility to enter horizontal and vertical offsets between the GPS antenna and sheave over which the camera sled cable passes, and a built-in caternary function. Using these data, Hypack 2012 automatically estimates the camera sled's position. Analysis of tow data indicate that horizontal positional uncertainty associated with the location of the camera sled recorded in Hypack is plus or minus 13 m.

  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)
    NOAA IRC
    Honolulu, HI 96818
    USA

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

    Contact_Instructions: e-mail preferred
  2. What's the catalog number I need to order this data set?

    Downloadable 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: 23-Apr-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)
NOAA IRC
Honolulu, HI 96818
USA

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

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


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