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 Kohala coast area of northwest Hawaii island. Data were collected using
the camera sled deployed from the R/V AHI during 6 days of survey.
These data provides optical observations that have been used to provide information on the distribution of coral communities
along the northwest coast of Hawaii
The island of Hawai'i is the southernmost island of the Hawai'ian archipelago. It is also the largest island with a land area of
nearly 10,500 sq km. It is the youngest island of the archipelago with ongoing volcanic activity.
Optical validation data were collected 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 June 26 - July 3, 2012, CRED personnel conducted towed video surveys along the Kohala coast of Hawaii, between Kawaihae and Anaehoomalu Bay.
The towed video camera was deployed from the NOAA vessel, the R/V AHI, a 25' survey launched, 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). The mission report for cruise SB1207 can be found here: http://www.soest.hawaii.edu/pibhmc/cms/cruise-catalog/
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 and still camera was
provided by 50 watt DSP&L LED Multi SeaLites. DSP&L SeaLaser 100 pair of parallel lasers was 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 meant that neither depth or
altitude were successfully transmitted to the control console.
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 used connected to the 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, as noted above it was not possible to get a value
for camera sled depth, and furthermore, the Hypack driver was not functioning correctly and would not allow cable-out readings to be
entered. 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
Data Files: Video data were recorded on video tape recorders and the position of the camera sled was recorded using Hypack 2012 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 SB1207 the tows were named HAW12001 to HAW12030. 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.
Please acknowledge the NOAA Coral Reef Ecosystem Division, Pacific Islands Fisheries Science Center as the source of
1845 WASP Blvd., Building 176
Benthic Habitat Mapping Group, Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), NOAA
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 SB1207, 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 2012 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 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 inputted directly into the TOAD database. The classified results were then exported as an excel spreadsheet and imported into ArcGIS v10, and 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: 000A1924.RAW 000_0008.RAW 000_0011.RAW 000_0020.RAW 000_0023.RAW 000_0026.RAW 000_0041.RAW 000_0048.RAW 000_0104.RAW 000_0109.RAW 000_0112.RAW 000_1320.RAW 000_1846.RAW 000_1917.RAW 000_1918.RAW 000_1924.RAW 000_1940.RAW 000_1945.RAW 000_1959.RAW 000_2003.RAW 000_2035.RAW 000_2037.RAW 000_2040.RAW 000_2108.RAW 000_2140.RAW 000_2235.RAW 000_2240.RAW 000_2241.RAW 000_2259.RAW 000_2302.RAW 000_2312.RAW 000_2338.RAW 000_2346.RAW
20.5 h of video data are avialable covering 22.25 km of seabed, recorded on 30 video tapes. List of video tapes (masters on mini DV, and backups on DVD) HAW12001 HAW12002 HAW12003 HAW12004 HAW12005 HAW12006 HAW12007 HAW12008 HAW12009 HAW12010 HAW12011 HAW12012 HAW12013 HAW12014 HAW12015 HAW12016 HAW12017 HAW12018 HAW12019 HAW12020 HAW12021 HAW12022 HAW12023 HAW12024 HAW12025 HAW12026 HAW12027 HAW12028 HAW12029 HAW12030