CRED Optical Validation Data at Maro Reef, 2004, to Support Benthic Habitat Mapping

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Frequently anticipated questions:


What does this data set describe?

Title:
CRED Optical Validation Data at Maro Reef, 2004, 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 Northwestern Hawaiian Islands, Maro Reef to support Benthic Habitat Mapping efforts.
Supplemental_Information:
Maro Reef, located at 25.4N, 170.6W, is the largest coral reef system in the Northwestern Hawaiian Islands with 1,508 sq. km of reef habitat in depths less than 100 m. There is no emergent land except for a few large coral blocks that are awash at low tide.

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 that for benthic habitat maps based on multibeam echosounder surveys. Camera sled deployments were conducted at night, usually between 1800 and midnight. Each tow was usually limited to 20 minutes of bottom time at a given location in order to allow for more tows to be conducted in a given work area and thus increase the spatial distribution of the observations. 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 the deck crew. The operator monitored a live video feed from the camera and began recording data on two video tape recorders. When the camera reached bottom the deck crew was notified by radio to stop lowering. 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 was deployed from the lower arm of the vessel's J-frame. The TOAD is a camera sled based on the Guildline MiniBat model 8820 tow body. The frame has been extensively modified from its original configuration and was configured with a single ROS model 54-00100-13 color underwater video camera and two 500 W DeepSea Power & Light model 710-0400601 underwater lights mounted on the original sled frame. The MiniBat pressure sensor and wing controller was also mounted on the frame but no wings were installed. Cable between the sled and the surface consisted of an underwater electrical cable (cable 1, blue in color) with a separate load-bearing line to support the sled frame. The electrical cable was clipped to the line at regular intervals upon deployment and removed upon recovery. The load-bearing line was led to the starboard capstan on the aft deck. All TOAD surface components were located in the Dry Lab in an equipment rack on the after bulkhead. After operations began we learned that the sled's pressure sensor was not working.

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 video tape recorders. The position of the camera sled was recorded using Guildline MiniBat In-Tow data acquisition software.

File naming convention: Each tow is given a name consisting of a 3-letter designator for the island area followed by a two-digit year and three-digit tow number. For example, during HI0401 the first tow was called MAR04001. Video tape labels, the navigation files (*.glo) and paper log forms are all annotated with the tow name. If the navigation file is edited during processing the file name has a suffix "a" added. For example, one of the navigation data files is named "MAR04001a.glo". Metadata were extracted from the navigation data and recorded to a file with the same name as the navigation file except that a file type of ".met" was appended; for example, "MAR04001a.glo.met"

Time Correlation: All times are based on UTC. Two clocks were set manually synchronized prior to starting data collection; the clock in the video character generator that was used to annotate the video tape and the TOAD data acquisition computer clock was used to annotate the navigation (*.glo) files. These clocks were set to UTC at the beginning of each evening's operations and then compared to one another prior to (and during) each tow. There were problems maintaining synchronization of the TOAD computer clock during this cruise. See the problems section for a description. (Problems with data could be described here.)

Resource Description: Digital video images that are 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), 200606, CRED Optical Validation Data at Maro Reef, 2004, to Support Benthic Habitat Mapping.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -170.81333
    East_Bounding_Coordinate: -170.37149
    North_Bounding_Coordinate: 25.5356
    South_Bounding_Coordinate: 25.36415

  3. What does it look like?

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

    Beginning_Date: 22-Sep-2004
    Ending_Date: 23-Sep-2004
    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?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in Decimal Degrees.

      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.

      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: No correction
      Depth_Resolution: 0.1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute Values

  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?

    Benthic Habitat Mapping Group, 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?

This data provides optical observations that will be correlated with bathymetry and acoustic backscatter imagery to develop a benthic habitat map of Maro Reef. 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-Oct-2004 (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. Navigation data were copied from the acquisition computer to the data archive. A metadata extractor (gloFilter.py, version 3/06) was run to summarize the navigation data and test for errors. If errors were detected they were corrected or flagged as appropriate and a new data file was made. This file's header was updated to document what type of processing occurred. A metadata file was recorded in the data archive in the same location as the navigation data. Processed navigation data were then read into ArcView 3.2 shapefiles using an ArcView Avenue script named "TOAD.Import.Playback", version 9/25/01, written by Ronald Hoeke.

  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 100 meters. There are three 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 used; no attempt is made to translocate this position to that of the tow block from which the camera is deployed. The difference between the tow block and the antenna is about 14 meters. The camera sled position is based a layback calculation that use ship's course, the amount of cable out and the camera sled depth to develop an estimate of the camera sled position. The amount of cable deployed is manually entered by the operator during a given camera tow.

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


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