CRED Optical Validation Data at Galvez Bank in the U.S. Territory of Guam, 2003 to Support Benthic Habitat Mapping

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What does this data set describe?

Title:
CRED Optical Validation Data at Galvez Bank in the U.S. Territory of Guam, 2003 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 in the U.S. territory of Guam, around the island of Guam itself and 3 banks within the territory, to support Benthic Habitat Mapping efforts during NOAA Ship Oscar Elton Sette cruise OES0308, from September 22-28, 2003.
Supplemental_Information:
Galvez Bank is part of the U.S. territory of Guam and located about 12 nautical miles (22 km) south-southwest of the island of Guam. The bank actually consists of several bathymetric highs, with a minimum charted depth of 20 m. Most of the bank top is characterized by moderate relief, lots of algae, scattered corals and a few reef fish. The bank has a fair amount of coral cover in several areas and a moderate number of reef fish. 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. Camera sled deployments were conducted at night, usually between 1800 and midnight. The duration of each tow varied but averaged about 40 minutes of bottom time at a given location. The camera sled was deployed from the port J-frame mounted amidships on the NOAA Ship Oscar Elton Sette. At each station the ship was positioned with the wind on the port 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 using a capstan. The operator monitored a live video feed from the camera and began recording data on a video tape recorder. 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 port side 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 equipped with an ROS model 54-00100-13 color underwater video camera as the primary data collection instrument. The ROS camera was mounted to point at approximately a 45 degree angle toward the seafloor. A Deep Sea Power and Light model 2050 MultiSeaCam low-light color video camera was also mounted on the sled and aimed straight ahead. The signal from this camera was fed to a second video monitor to provide warning of underwater obstructions the sled might be headed for. Illumination was provided by two 500 W DeepSea Power & Light Multi-SeaLite model 1050 underwater lights mounted on the original sled frame. The lights were located near the base and each side of the sled to provide the maximum possible horizontal distance from the ROS camera. Cable between the sled and the surface consisted of a underwater electrical cable (cable 2, black in color) with an internal kevlar strength member to support the sled frame. The cable was led from the camera sled over a 22-inch diameter sheave hung from the J-frame, and from there around a gypsy head mounted on the alternate CTD winch, amidships on the vessel's port side. All TOAD surface components were located in the Dry Lab in an equipment rack on the after bulkhead. Data Files: Video data were recorded on a video tape recorder. The position of the camera sled was recorded in WGS-84 using Guildline MiniBat In-Tow data acquisition software and a data feed from a shipboard Northstar Chartplotter. 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, which increments by one for each new tow around that island. For Galvez Bank the designator is "GAL." During OES0308 (NOAA Ship Oscar Elton Sette's 8th cruise in calendar year 2003) the consecutive numbers started at GAL03001. Video tape labels, the navigation files (*.glo) and paper log forms are annotated with the tow name and number, e.g., GAL03002. If the navigation file is edited during processing the file name has a suffix 'a' added. For example, for a navigation data file named "GAL03002a.glo," the 'a' would indicate that 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, 'GAL03002a.glo.met. Time Correlation: All times are based on UTC. Two clocks were manually synchronized prior to starting data collection; the clock in the video character generator that was used to annotate the video tape, and the clock in the TOAD data acquisition computer. 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 might 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), 20110901, CRED Optical Validation Data at Galvez Bank in the U.S. Territory of Guam, 2003 to Support Benthic Habitat Mapping.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: 144.42
    East_Bounding_Coordinate: 144.49
    North_Bounding_Coordinate: 13.11
    South_Bounding_Coordinate: 13.02
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 26-Sep-2003
    Ending_Date: 27-Sep-2003Currentness_Reference: ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Video imagery, track line navigtion 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 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), NOAA National Marine Fisheries Service (NMFS)
    NOAA IRC
    Honolulu, HI

    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 correlated with bathymetry and acoustic backscatter imagery to develop a benthic habitat map of Galvez Bank. 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: 17-Oct-2005 (process 1 of 1)
    After a tow was completed the video tape data and still photographs were reviewed by spot-checking to verify that data were recorded. Navigation data were copied from the acquisition computer to the data archive. A metadata extractor (gloMeta.py, version 9/28/04) 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 Avenue script named `toadimport.playback.ave', version 9/25/01, written by Ronald Hoeke.

    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 (PIBHMC_tow). Five points were classified at 30 second intervals and codes were inputted into spreadsheet. Spreadsheet was saved as dbase file, imported into ArcGIS, 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. For more information on classification 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?
    The horizontal position accuracy for the camera sled position is estimated at plus or minus 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 largest source of error is uncertainty associated with the sled's position relative to the tow 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 Sciences Center (PIFSC), NOAA National Marine Fisheries Service (NMFS)
    NOAA IRC
    Honolulu, HI

    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: 15-Dec-2024
Metadata author:
Pacific Islands Benthic Habitat Mapping Center (PIBHMC), Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Sciences Center (PIFSC), NOAA National Marine Fisheries Service (NMFS)
NOAA IRC
Honolulu, HI

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 2.9.44 on Wed Mar 12 20:52:18 2025