Optical validation data were collected using a Tethered Optical Assessment Device (TOAD), an underwater sled equipped with an underwater digital video camera, digital still camera and lights, in the Kahekili coast area of western Maui island. Data were collected using the camera sled deployed from the R/V AHI during 7 days of survey.
These data provide optical observations that have been used to provide information on the distribution of coral communities along the west coast of Maui
Optical validation data were collected with the Tethered Optical Assessment Device (TOAD), a sled equipped with underwater video camera, digital still camera and lights. These data are used to provide optical information regarding benthic and fish communities. They have also been used to provide ground-truth validation for benthic habitat maps based on multibeam echosounder surveys, but these are presented in a separate product, available on the PIBHMC website. Operations Description: From February 6 - 13, 2014, CRED personnel conducted towed video surveys along the Kanapali - Kahekili coast of Maui, between Puunoa Point and Kahana Point. The towed video camera was deployed from the NOAA vessel, the R/V AHI, a 25' survey launch, designed for habitat mapping surveys. Operations were conducted during daylight hours, with video data collected using an underwater camera sled, designed and fabricated by Deep Ocean Engineering, Inc. (DOE). Equipment Description: The TOAD sled body is constructed from a shortened Phantom ROV body with a tail piece added for stability. The camera sled was equipped with a Deep Sea Power & Light (DSP&L) Multi SeaCam 2060 low-light color video camera, angled downwards to provide imagery of the seabed while allowing some view of upcoming obstacles, and a downward-facing Ocean Imaging System 12000 digital still camera (consisting of a Nikon D90 digital SLR camera within an aluminum housing). Illumination to the video camera was provided by 50 watt DSP&L LED Multi SeaLites. Illumination to the still camera was provided by a remote flash head (Ocean Imaging Systems). A pair of DSP&L SeaLaser 100 lasers were used for scaling of still images. The sled also had a Tritech PA200 Altimeter to detect the height of the camera sled above the seafloor, and a pressure (depth) sensor and fluxgate compass, all installed inside an electronics bottle. However, during this mission, a fault within the system disabled the lazers during most of the tows. The camera sled was attached to the control console (situated in the cabin) via a 150-m length (0.5" diameter) umbilical cable, with a working load limit of 400 lbs and a breaking strength of 2000 lbs, and is deployed via a pot-hauler with a 300lbs (SWL) capacity, mounted on the rear-starboard corner of the cabin. A video display monitor mounted on the control console was used to monitor the position of the sled relative to the seafloor. Video data were recorded to digital video cassette using a video recorder mounted on the control console. A serial cable was connected to a POS-MV, to provide position of the vessel. Hypack hydrographic software (version 2012) was used to record position data (from POS-MV) and time. Usually, the length of umbilical cable in the water would be manually entered into Hypack, and this would be used in conjunction with the camera sled depth and vessel position to calculate layback and determine the latitude and longitude of the sled. The calculated position is then recorded in Hypack. However, it was not possible to get accurate cable out values for calculating layback due to the use of a new, unmarked cable. Therefore, Hypack was set up to use vessel position as a proxy for camera sled position, and offsets were applied for the relative position of the pot-hauler to the AHI point of origin. During operations it was noted that it was possible to maintain the umbilical cable at close to vertical for much of the time, with the result that the sled was usually close to directly below the AHI pothauler. Data Files: Video data were recorded on video tape recorders and the position of the camera sled was recorded using Hypack 2013 hydrogrpahic 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. During cruise MP1401 the tows were named MAI14001 to MAI14035. Video tape labels and paper log forms are annotated with the tow name. Data recorded using Hypack software were of the format 000_HHMM where HHMM was the UTC time. Time Correlation: All times are based on UTC. Clocks were manually synchronized prior to starting data collection each day of operations. Resource Description: Digital video imagery that is geo-referenced to navigation files.
ground condition
Please acknowledge the NOAA Coral Reef Ecosystem Division, Pacific Islands Fisheries Science Center as the source of this information.
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Benthic Habitat Mapping Group, Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), NOAA
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The horizontal position accuracy for the camera sled position is estimated at 40 meters. There are two primary sources of this error. The vessel positioning is estimated at 25 m horizontal accuracy, and as vessel position was used for camera sled position (with measured offsets between the vessel point of origin and the pothauler applied), an additional inaccuracy comes from the distance of the camera sled from the horizontal position of the vessel. During MP1401, survey depth was relatively shallow (<100 m) and this, combined with the near to vertical cable angle, means that this second source of uncertainty is estimated to be <15 m.
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 2013 software that include time and vessel position, were copied from the acquisition computer to the data archive. Tow-specific metadata were recorded in a custom database. Raw Hypack data files were exported as comma-delimited text files which were then modified in Excel so that additional information could be added, before being imported into ArcGISv10.1 and saved as shapefiles. Additional depth data was extracted from underlying bathymetry using "Extract values to points" tool available in ArcGIS. The dbf of the shapefile was then imported into the TOAD database, which is a custom-built Access 2007 database. The benthic habitat for each tow was classified using the PIBHMC_tow classification scheme. Five points were classified at 30 second intervals and codes were input directly into the TOAD database. The classified results were then exported as an excel spreadsheet and imported into ArcGIS v10, then saved as a shapefile. Percent scleractinian coral was colour symbolized in optical validation maps with underlying fields of different substrates contained within the attribute table of the shapefile. 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
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.
Each comma-delimited record contains informaation on the UTC date and time, horizontal position of the sled, and heading of the ship over the period of time that the camera sled is in the water. List of navigation files: 000_0140.RAW 000_2004.RAW 000_0246.RAW 000_2043.RAW 000_2124.RAW 000_2154.RAW 000_2254.RAW 000_2322.RAW 000_2352.RAW 000_0020.RAW 000_0047.RAW 000_0127.RAW 000_0211.RAW 000_0242.RAW 000_0314.RAW 000_2040.RAW 000A2124.RAW 000_2146.RAW 000_2214.RAW 000A2254.RAW 000_2320.RAW 000_2343.RAW 000_0000.RAW 000_0012.RAW 000_0050.RAW 000_0117.RAW 000_0142.RAW 000A0000.RAW 000_0021.RAW
8.5 h of video data are available covering 19.4 km of seabed, recorded on 11 video tapes. List of video tapes (masters on mini DV, and backups on DVD) MAI14001 MAI14002 MAI14003 MAI14004 MAI14005 MAI14006 MAI14007 MAI14008 MAI14009 MAI14010 MAI14011 MAI14012 MAI14013 MAI14014 MAI14015 MAI14016 MAI14017 MAI14018 MAI14019 MAI14020 MAI14021 MAI14022 MAI14023 MAI14024 MAI14025 MAI14026 MAI14027 MAI14028 MAI14029 MAI14030 MAI14031 MAI14032 MAI14033 MAI14034 MAI14035
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