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LiDar, which stands for Light Detection and Ranging, is a surveying method that measures distance to a target by illuminating that target with a pulsed laser and then measuring the reflected pulses with a sensor. Wavelengths can then be used to make digital 3D representations of the target. The target can be anything from buildings, vehicles and bridges, through to mountains and tree covered forests. In fact virtually anything.

Vistaworx was asked by one of our clients, who are involved with the nuclear build at Hinkley Point C, if we could survey a series of six structures 500mtrs offshore. The original brief was to undertake 3D Photogrammetry and supply photographic captured data to a specified accuracy. During the initial meeting, the brief was to provide a highly accurate dataset of six very large structures to within very small tolerances. Photogrammetry was the initial 'go to' technology that was being considered, but after a not so short discussion, it was suggested that we could combine both LiDar and 3D photogrammetry, both data being captured simultaneously, and by combining the two datasets, we could provide a higher standard of accuracy that was required.

Of course the project not only consisted of the actual recce and deployment time, safety and planning was paramount. Before the project commenced, we had to complete the necessary risk assessments, attend a one day marine survival course, an ENG 1 medical, induction course and the usual notification to local ATC prior to the task day. Oh, and the purchasing of a large packet of Kwells seasickness pills!

The task had many challenges, not least having to deploy the team during a specific time when the tide was at it's lowest level, thus exposing the particular areas of the structures that needed to be captured. Throw into the works that there were only two windows of opportunity, five days at the end of May and six days at the end of June. Combine this with the need for decent weather and the availability of the sea vessel to deploy the team up the Severn estuary to the task area, and it can be seen that the whole project was anything other than a 'walk in the park.'

We had included in the original schedule and quotation a recce/test day and two deployment days. Capturing data in an alien environment, in close proximity to large steel structures, with take offs and landings from a moving steel vessel, was an unknown factor and was a challenge the whole team were eager to accomplish. The test day proved useful and allowed us time to establish several technical aspects including the integrity of telemetry and GPS. We also used this day to capture 'land' data using a Leica P40 laser scanner on the platform adjacent to the six main structures. The aircraft for the project was the DJI S1000 octocopter, a beast of a heavy lift airframe capable of lifting the heavier than normal equipment that we were going to be using.

Our initial task day was always going to be somewhat of a challenge, mainly due to the fact that there was a question mark over the suitability of the weather a couple of days prior to the deployment. The day was in fact hampered, as the winds were in excess of 20mph with gusts upwards to 28mph on occasions. We also had technical issues with the RTK GPS unit on the aircraft. The two issues prevented us from capturing any data. However, later in the day, the wind had subsided a little and so this allowed us to deploy our standby aircraft and capture, what turned out to be, exceptionally high quality photogrammetry data. This high quality data was aided by the use of a set of Propellor Aeropoints that had been located at suitable points on the platform. Disappointed that we had failed to capture the LiDar data, we were nevertheless hopeful that a successful conclusion to the project would be forthcoming on the second backup task day.

Our final opportunity had arrived and the weather forecast was favourable. The team consisted of two personnel on shore in charge of a ground station, three of our clients on the ship and ourselves; Alex, my partner for the project, Marcin who was in sole charge of LiDar capture and myself. Flying this beast of a machine at distance, down to only a metre above sea level, was somewhat nerve wracking to say the least! The weather came 'up trumps' and with cloudy, but bright conditions, the light winds died down to a perfect calm and we managed to capture some highly excellent data. The combination of both LiDar capture and high quality photogrammetry allowed us to provide our client with incredibly accurate data, which far surpassed their original expectations.

LiDar can be used in many areas of construction, agriculture, property inspection work and also forestry management where capturing accurate positional and topographical data is important. Our LiDar
unit for example, is a multi-return system which is capable of penetrating tree canopies, thus allowing the surveying and rendering of 3D models of the terrain below, something that is impossible in any other way.

If you are interested in seeing how Vistaworx can help you with LiDar, photogrammetry, or with any other area of aerial data capture, then why not call for an informal chat.