Wednesday, 25 June 2014

Hexacopter flight over tetrapod site

Last week Tim Kearsey, along with BGS colleagues Ed Haslem and Pete Hobbs were at our main field site in the Scottish Borders flying a hexakopter survey over the rocks exposed in the foreshore. A hexakopter is a type of model helicopter with six rotor blades. This keeps it very steady in the air and means we can use it to do aerial photography from a low height, rather than an aircraft.  The hexakopter has a normal digital camera under it which takes a photo every second. It also has an onboard GPS which records the position of each photograph. These photos can then be combined in a computer using programs that use both the GPS position and the features in the photos (in a similar way that software that allows you to build several photos into a panorama does). This creates a single image with is also scaled so we can measure feature on it.
The Hexakopter in action over the sandstone beds
The reason we are  doing this survey is because the rock there are all up on end, that is to say have been rotated through 90 degrees  since the time they were formed. This gives us a unique 500m by 200m view of the river systems and floodplain in which the tetrapods lived. However, unlike a cliff, it is impossible to stand back and get a broad picture view.

Ed Haslam and Tim Kearsey using a dGPS to plot control points to aid combination of the photos
The images collected by the hexakopter will help us to understand the large scale shapes of the sandstones and the units in between. This will help us to answer questions like ‘what were the rivers like where the tetrapods lived?’; ‘were there lakes?’; ‘how close were we to the sea at the time the tetrapods lived?’
Until next time
Tim Kearsey

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