Difference between revisions of "Underwater video"

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Fig 5: Here, the stony bottom of Öresund (the strait between Denmark and Sweden and one of the entries to the Baltic Sea) is shown as a frame from a video (left) and as an acoustic image from a Side Scan Sonar survey. Both representations have advantages and disadvantages and they should here be seen as complements rather than alternatives.
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Fig 5: Here, the stony bottom of Öresund (the strait between Denmark and Sweden and one of the entries to the Baltic Sea) is shown as a frame from a video (right) and as an acoustic image from a Side Scan Sonar survey (left). Both representations have advantages and disadvantages and they should here be seen as complements rather than alternatives.
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The cost of a simple video system is nowadays not prohibitive. It is mostly non-intrusive and non-destructive; one exception is for example the REMOTS sediment profiler, vertically  slicing  the  sediment-water interface and  viewing the sediment in  profile  
 
The cost of a simple video system is nowadays not prohibitive. It is mostly non-intrusive and non-destructive; one exception is for example the REMOTS sediment profiler, vertically  slicing  the  sediment-water interface and  viewing the sediment in  profile  
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The sometimes labor intensive evaluation of video material can be considered a disadvantage, and there is sometimes a risk of inter-observer biasing that should be considered and addressed if several observers are working together.
 
The sometimes labor intensive evaluation of video material can be considered a disadvantage, and there is sometimes a risk of inter-observer biasing that should be considered and addressed if several observers are working together.
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== References ==
 
== References ==

Revision as of 16:23, 26 May 2007

Video is Latin for "I see”. In this context, the term video refers to the technology of (electronically) capturing, sometimes manipulating, storing and/or broadcasting, and finally reproducing a sequence of still images at a rate that is perceived by the brain as being in motion.

Definition of Underwater video:
Underwater video is when video technology is used in water (or other fluids) in for example marine, lacustrine, or industrial environments.
This is the common definition for Underwater video, other definitions can be discussed in the article

Video imaging in wells and boreholes is similar to underwater video, but puts constraints on the shape and size of the equipment, as does for example underwater video in sewer pipes, nuclear power plants or fish tanks.

Sometimes the term video is referring to the actual equipment (video recorders, cameras) and/or video cassettes or even the recorded content.

This article is about the applications for underwater video; cf. the articles on Underwater video systems which is about equipment and Video Technology, which deals with video as such.

History

The first attempts in the field of underwater photography were made with a pole mounted camera in the 1850s by the British William Thompson, and several successful attempts were made over the next decades. The first published scientific results from an underwater camera are from 1890 and were made by the French naturalist Louis Boutan [1] who developed underwater photography to a useful method, inventing the underwater flash and other equipment. Photographic techniques, including cinematography, were used exclusively for many years, as television at that time was at its very earliest development stage.

UWVideo Boutan.jpg

Fig 1. Louis Boutan, the first published underwater photographer pioneered not only photography, but diving equipment in general.

Underwater video has existed since the 1940s. The first published results are by Harvey Barnes in Nature 1952 [2] , but it is mentioned in the article that the Admiralty (UK) made successful attempts before that, and that Barnes himself started development of the method in 1948.


UWVideo Barnes.jpg

Fig 2. The first published article on underwater video featured a picture of nothern krill, Meganyctiphanes norvegica. The size of these are normally 25-30 mm.


Applications

Since then, underwater video has been used for many purposes. The references given are not selected to be the first published results (although they may be), but only given as examples and starting points for a selected few applications.

From the start, underwater video has been used for [Marine_biology marine biological] studies. It may be abundance [3] [4] behavioral studies [5] [6] habitat mapping [7] [8] studies of fishing and trawling [9] [10] and whether the seabed is damaged or not by it [11] [12] even in combination with a water sampler [13] and to separate living corals from dead [14].

It has also been used for marine geology [15] , sediment studies [16] , tidal microtopography [17] , bridge [18] and pipeline [19] inspections, sports [20] , marine archaeology [21] , entertainment, education and more.

The reasons for this widespread use are several. The most viable alternative to underwater video for making visual observations (if you want moving pictures!) is a to be a diver or to use a waterscope. Both these methods have limitations regarding depth, observation time, temperature, accessibility, documentation procedures etc., that makes video superior in many of not most cases.

UWVideo Zostera.jpg

Fig 3. Video is often used for studies of marine life; here common Eelgrass (Zostera sp.)


A bibliometry made in 2000 [22] shows that the number of papers in the study on underwater video peaks in the mid 1990s. The reason for this is probably that before this, the equipment was expensive and bulky, and thus not very apt for underwater use. The evolution of electronics made the video equipment small (and cheap) enough for widespread use in the 1990s, and many novel applications were reported. Today, papers about video technology per se are not as numerous – not because video is not used anymore, but because video is a standard method.

In spite of this, there are many misconceptions and some confusion about the technology, in particular when it comes to the evolving digital video systems. Some of these are dealt with in other Coastal wiki articles; i.e. Underwater video systems about equipment and Video Technology, which deals with video as such.

Pros and cons

For any mapping method there is a tradeoff between resolution, coverage, labor intensity and information content [23] , see figure 1, where some video methods are compared to other. You may notice that video performs well in terms of resolution and information content, not so good when it comes to workload and areal coverage.

UWVideo Fig1.png

Fig 4: Video methods compared to other methods. Modified after [23].


One obvious advantage of video is, that you can use your most capable perceptional system – the vision. What you get is what you see. As opposed to other imaging methods (for example underwater acoustics) you can see colors, shapes etc. (mostly) the way you are used to.

UWVideo OresundExample.jpg

Fig 5: Here, the stony bottom of Öresund (the strait between Denmark and Sweden and one of the entries to the Baltic Sea) is shown as a frame from a video (right) and as an acoustic image from a Side Scan Sonar survey (left). Both representations have advantages and disadvantages and they should here be seen as complements rather than alternatives.


The cost of a simple video system is nowadays not prohibitive. It is mostly non-intrusive and non-destructive; one exception is for example the REMOTS sediment profiler, vertically slicing the sediment-water interface and viewing the sediment in profile [24]. Another advantage is that it is easy to communicate results to both peers and to non-specialists.

The most prominent limitation on the use of underwater video is visibility, or rather the lack of underwater visibility. Lighting conditions, scattering particles in the water, the water itself, reduce the visibility (in most practical cases) to a range of a few tens of meters, often less. Due to this (and camera resolution limitations) relatively small areas are imaged compared to for example side-scan sonar.

UWVideo Cableinspection.jpg

Fig 6 Cable and pipeline inspections made by ROVs (here a high voltage cable is shown) are time consuming, partly due to visibility limitations. Here, only 4-5 meters of the cable can be seen at a time, while this particular cable (a short one!) is 38 km.


The evaluation is obviously biased towards visual features but studies using ultraviolet light are reported [25] , and although infrared light is rapidly attenuated in water it has reportedly been used for illumination [26] .

The sometimes labor intensive evaluation of video material can be considered a disadvantage, and there is sometimes a risk of inter-observer biasing that should be considered and addressed if several observers are working together.

References

  1. ↑ Boutan, L. (1893); Mémoire sur la Photographie Sous-Marine; Archives de Zoologie Expérimentale et Générale; 3ème sér., 1, pp. 281-324
  2. ↑ Barnes, H. (1952); Underwater television and marine biology; Nature, 169, pp. 477–479
  3. ↑ Smith, C. J., Papadopoulou, K.-N. (2003); Burrow density and stock size fluctuations of Nephrops norvegicus in a semi-enclosed bay; ICES Journal of Marine Science; 60, pp. 798–805
  4. ↑ Moser, M. L., Auster P. J., Bichy, J. B. (1998); Effects of mat morphology on large Sargassum-associated fishes: observations from a remotely operated vehicle (ROV) and free-floating video camcorders; Environmental Biology of Fishes; 51, pp. 391–398
  5. ↑ Grémillet, D., Enstipp, M. R., Boudiffa, M., Liu, H. (2006); Do cormorants injure fish without eating them? An underwater video study; Marine Biology; 148, pp. 1081–1087
  6. ↑ Esteve, M. (2007);Two examples of fixed behavioural patterns in salmonines: female false spawning and male digging; Journal of Ethology; 25:1, pp. 63-70
  7. ↑ Ryan, D. A., Brooke, B. P., Collins, L. B., Kendrick, G. A., Baxter, K. J., Bickers, A. N., Siwabessy, P. J. W., Pattiaratchi, C. B. (2007); The influence of geomorphology and sedimentary processes on shallow-water benthic habitat distribution: Esperance Bay, Western Australia; Estuarine, Coastal and Shelf Science; 72:1-2, pp. 379-386
  8. ↑ Abdo, D., Burgess, G., Coleman, K. (2004); Surveys of benthic reef communities using underwater video; Long-term monitoring of the great Barrier reef Standard Operational Procedure Number 2, 3rd Revised Edition; Australian Institute of Marine Science, Townsville 2004; ISBN0-64232231
  9. ↑ Zhou, S. Shirley T. C. (1997); Performance of two red king crab pot designs; Canadian Journal of Fisheries and Aquatic Sciences / Journal canadien des sciences halieutiques et aquatiques; 54, pp 1858–1864
  10. ↑ Cooper, C., Hickey, W. (1987); Selectivity experiments with square mesh cod-ends on haddock and cod; IEEE OCEANS; 19, pp. 608-613
  11. ↑ Vorberg, R. (2000); Effects of shrimp fisheries on reefs of Sabellaria spinulosa (Polychaeta); ICES Journal of Marine Science; 57 pp. 1416–1420
  12. ↑ Linnane A., Ball B., Munday B., van Marlen B., Bergman M., Fonteyne R. (2000): A review of potential techniques to reduce the environmental impact of demersal trawl; Irish Fisheries Investigation Series Publications (New Series) No. 7; ISSN0578-7467
  13. ↑ Dounas, C. G. (2006); A new apparatus for the direct measurement of the effects of otter trawling on benthic nutrient releases; Journal of Experimental Marine Biology and Ecology; 339, pp. 251 – 259
  14. ↑ Harris, P. T., Heap, A. D., Wassenberg, T., Passlow, V. (2004); Submerged coral reefs in the Gulf of Carpentaria, Australia; Marine Geology; 207:1-4, pp. 185-191
  15. ↑ Field, M. E., Nelson, C. H., Cacchione, D. A., Drake, D. E. (1981); Sand waves on an epicontinental shelf: Northern Bering Sea; Marine Geology; 42:1-4, pp. 233-258
  16. ↑ Osborne, P. D., Greenwood B. (1991); Frequency dependent cross-shore suspended sediment transport. 2. A barred shoreface; Marine Geology; 106, pp. 25-51
  17. ↑ Lund-Hansen L., Larsen E., Jensen K., Mouritsen K., Christiansen C., Andersen T., Vølund G. (2004); A new video and digital camera system for studies of the dynamics of microtopographic features on tidal flats; Marine Georesources and Geotechnology; 22: 1-2, pp. 115-122
  18. ↑ DeVault, J.E. (2000); Robotic system for underwater inspection of bridge piers; Instrumentation & Measurement Magazine, IEEE; 3:3, pp. 32-37
  19. ↑ Gracias, N., Santos-Victor, J. (2000); Underwater Video Mosaics as Visual Navigation Maps; Computer Vision And Image Understanding; 79:1, pp. 66-91
  20. ↑ Blanksby, B. A., Skender, S., Elliott, B. C., McElroy, K., Landers, G. J. (2004); An Analysis of the Rollover Backstroke Turn by Age-Group Swimmers; Sports Biomechanics; 3:1, pp. 1-14
  21. ↑ Coleman D. F., Newman J. B., Ballard R. D (2000); Design and implementation of advanced underwater imaging systems for deep sea marine archaeological surveys; OCEANS 2000 MTS/IEEE Conference and Exhibition;1, pp. 661-665
  22. ↑ Harvey, E., Mladenov, P. (2001); The uses of underwater television and video technology in marine science: a review; appears in Harvey, E.S. Cappo M.; Direct sensing of the size frequency and abundance of target and non-target fauna in Australian Fisheries - a national workshop. 4-7 September 2000, Rottnest Island, Western Australia. Fisheries Research Development Corporation; ISBN 1-740520580
  23. ↑ 23.0 23.1 Kautsky, H. (2006); Östersjöns vegetationsklädda bottnar sedda med olika ögon – hur slarvig får man vara; Proceedings of Marin Undersökningsteknik 2006 (MUT06); Engineering geology, Lund university, Lund
  24. ↑ Rhoads, D., Germano, J., Boyer, L. (1981); Sediment Profile Imaging: An Efficient Method of Remote Ecological Monitoring of the Seafloor (REMOTS SYSTEM); IEEE OCEANS; 13:Sep 1981, pp. 561- 566
  25. ↑ Losey, G.S. (2003); Crypsis and communication functions of UV-visible coloration in two coral reef damselfish, Dascyllus aruanus and D.reticulatus; Animal Behaviour; 66:2, pp. 299-307
  26. ↑ Hinch, S., Collins N. C. (1991); Importance of diurnal and nocturnal nest defense in the energy budget of male smallmouth bass: insights from direct video observations; Transactions of the American Fisheries Society 1991;120, pp. 657–663

Useful links

JNCC Joint Nature Conservation Committee (UK) Marine Monitoring Handbook (2001); in particular PG 3.5 Drop down video, PG 3.13 Subtidal hand-held video, PG 3.14 Towed sledge


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