Plan-view photography is another discrete sampling technique that employs a frame-mounted downward looking camera to obtain plan-view photographs of a small patch (typically 2 m2) of the seafloor surface. The plan-view images provide an undisturbed view of the seafloor surface and are useful for indicating sediment composition and surface biological activity. A plan-view camera is often added to the SPI frame to provide a seafloor surface image of the SPI sampling area.
See NOAA's summary table at summary view of underwater photography technique (170 KB PDF).
Like aerial photography plan-view underwater photography is also limited by water clarity, but due to its small image footprint, generally much of the time less than 1 square meter, it can still be used more universally. There are several types of underwater photographic systems that can be used to investigate benthic habitats. It is often incorporated in to the same equipment package as the underwater video.
Used in conjunction with underwater video imaging, plan-view photography can help evaluate biological conditions in the water column as well as on the seafloor. The use of sled mounted cameras,with acoustic USBL ( Ultra Short Base Line ) tracking sensors, that can be towed by a survey vessel close to the seabed have become an important part of the benthic habitat mapping process. Cameras can also be mounted on remotely operated vehicles that can be driven around the seafloor as well as diver held or seabed sampling frames to collect detailed information over a localised area. The shutter on the camera can be released either manually from shipboard or automatically using an internal trigger mechanism.
Codec Comparison Click here for information compiled by James Wise.Purpose:
To analyse a range of popular codecs and assess their suitability for use in a variety of applications. Also to explore and understand issues related to the different types of artefacts that var ious codecs and codec families produce, how the MPEG compression scheme works and which codec/codec families are best suited for use in specific applications.Target Uses / Environments:
Photographic techniques provide detailed information regarding sediment composition and biological activity. Plan-view photography can be used to monitor benthic communities such as shellfish beds and submerged aquatic vegetation beds.