The Requirement:

Glasgow City Chambers' required a topographical survey of their roof to allow future development to take place. Due to the age and complex nature of the roof it was proposed the work be carried out using an Unmanned Aerial Vehicle (UAV). The aerial survey was coordinated by our UAV Pilot Charles Watson, who is a Civil Aviation Authority (CAA) approved pilot. Charles was part of a four person survey team, including Technical Manager John Baggs and our partners in this task BB Stratus Ltd. They were commissioned to carry out the flying as they have additional CAA permissions allowing them to operate a UAV in congested areas, such as Glasgow City Centre. 

The Solution

The main benefit of using the UAV to complete the survey was the reduced risk to both our surveyors and members of the public. Collecting the data this way meant the work could be carried out in one visit and that there was no need for fall arrest systems, scaffolding and other control measures that would have added both time and cost to the project.

Work was carried out on a Sunday morning as there would be minimal public presence. The survey consisted of 3 flights from a height of 40m to take aerial photography. Ground control points were surveyed across the roof to improve the accuracy of the survey and the orthorectified image.

Photographs collected during the flight were then processed using our photoscan software producing an accurate georeferenced orthophoto. This allowed us to produce a dense point cloud, which would allow CADmeleon to extract a "wire-frame" drawing, including features such as roof canopy, peaks, walkways, drains and skylights.

The final deliverables issued to the client included a CAD drawing of the roof, a high resolution orthophoto and oblique imagery of Glasgow City Chambers' roof. 

The Conclusion

By using the UAV the survey the work was completed within 1 day on site with minimal risk to both surveyors and members of the public. The client can now start planning for developing the roof with an accurate topographical survey.

There is also the added benefit of up to date high resolution aerial photography. This can have many uses from both marketing and roof inspection purposes.

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