Engineering Geology at Lund University has over the last 20 years or so been working with underwater assessments of different types. A significant part of the work is dedicated to the use of video for mapping and inspection purposes.

"Here, we work mainly with technology and methodology – the applications are found in several fields, ranging from inspection and monitoring of objects to pre-investigations and marine habitat mapping. We look forward to be able to work with the LYYN™ technology, which we think is directly applicable to increase the efficiency in video assessments." says Peter Jonsson, lecturer, Engineering Geology.

Video is often an excellent alternative for mapping and monitoring of objects and areas under water. To use video in this way, a fixed methodology has to been used for both the field work and the evaluation. If this is true, you have a good tool to establish for example vegetation or habitat maps, or to describe a ship wreck or other object.

The video film can be made in several ways. The obvious is to use a diver with a handheld camera, but the camera can be dropped over the side of a ship, towed after a ship or be on a remotely operated underwater vehicle. All these methods share a common limitation: If the visibility in the water is low, the efficiency is decreased. If the efficiency is low, the time spent in field is increased, and this is expensive.

Bad visibility is common, especially in shallow waters near the coast, in rivers and lakes, but also the in the Baltic as a whole – the Baltic is notorious for its sometimes bad visibility. If the video film is shot in for example water-filled mine shafts or wells, conditions with low visibility is generally a rule rather than an exception.

The visibility in water is limited by particles in the water, the color of the water, strength and direction of the available light, etc. The daylight is relatively quickly attenuated towards depth, and the color composition is changed. First, the red light is attenuated, and below 15-20 meters (50-60 ft) the remaining light is mainly green, which clearly affects the image, that looks entirely green in color.

Incandescent lights are not always a solution – the backscatter from particles in the water can disturb the picture, making the result worse than expected; compare to driving through a blizzard with your main beam headlight on.

"So far, we have made initial tests with the LYYN™ technology. In several of the tested cases, LYYN™ showed impressing results on video footage being almost unusable, or even discarded. Prominent green coloring in the pictures disappeared, gray foggy picture without detail showed surprisingly much information, and are probably good enough for further evaluation.

The brief tests are, put mildly, promising. The future co-work will initially be centered on a systematic evaluation of the benefits and limitations of the method, when used in underwater applications. In the future we hope to be able co-operate in finding new applications." ends Peter Jonsson.

Contact: Peter Jonsson, phone +46 46 222 49 58,
e-mail

Engineering Geology is a part of Lund University, the largest unit for research and higher education in Sweden. We work with engineering geology and applied geophysics. Our contributions are found in areas as different roads, bridges, dams and tunnels, wells thousands of meters deep, measurements of the Greenlandic icecap, underwater mapping, geothermal energy, groundwater mapping in arid or tropical areas, etc. Here, we develop instruments as well as methods for measurements and evaluation.

You can reach us at: phone +46–46 222 7425, e-mail or at www.tg.lth.se