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 pothauler.
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.