Aerial Surveys Hertfordshire – St Albans Cathedral

Level of detailThe tower is the oldest central cathedral tower in Britain, built by the Normans between 1077 and 1088. The Normans used flint & bricks which were in fact recycled from the Roman city of Verulamium at the bottom of the hill, where Alban had once lived.

The material used in the construction of the Tower means that no one brick was the same & would have to be drawn manually. To draw every brick on the Norman Tower would not only be a lengthy process but also a costly one, there are thousands of bricks on one elevation alone. Although we have the technology & expertise to carry out this type of work through terrestrial Laser Scanning and/or photogrammetry the questions we really had to ask ourselves was ‘is it really necessary, would this give our client best value for money….. the answer was a clear no.

Through close consultation with St Albans Cathedrals Development Manager, Stephanie Pisharody, we were able to come up with a workflow which would provide a deliverable they would be able to take forward & manage themselves throughout the fundraising programme.

Aerial SurveyingSurveying the Norman Tower from the air would ensure that we could get the vantage points necessary to record the brick work & features of the Tower down to the level at which the lower buildings meet the Tower- information that is simply not obtainable from the ground.

We chose to use our DJI M210 Small Unmanned Aerial Vehicle (SUAV) to carry out the site work as it offers a versatile & stable platform.
Using drones for aerial surveying works on the basis of photogrammetry where numerous high definition photographs of a site are taken, most projects will involve hundreds of high definition images being acquired. The large number of images are required to ensure sufficient overlap between images which is essential to build an accurate 2D or 3D model.

The photos are taken remotely by the camera onboard the drone which is operated by the remote pilot on the ground. The images are then processed in a specialist software package to produce an accurate 3D model of the site, in this case The Norman Tower. Once the model has been subjected to a thorough QA check for accuracy it is then exported in a format which can be used in AutoCAD where the survey drawings are produced.

Please note that In order for a drone to be used in relation to business the Civil Aviation Authority (CAA) must have issued a Permission to Fly Commercial Operations (Pfco) & the company or individual hold relevant insurances as well as having the land owner’s permission. Terrain surveys have 2 qualified remote pilots, a Pfco from the CAA & the relevant insurances to carry out aerial surveying. 

 

Customer Satisfaction
Ensuring our clients receive what they need instead of what is ‘thought’ they should have is an approach we always take at Terrain Surveys. This was very much appreciated as highlighted by Stephanie’s comments Below;

“We were delighted to launch our ‘Adopt a Brick’ programme at the Cathedral last week. This couldn’t have happened without your help and advice, coming up with a great solution to create an annotated tower graphic, and of course the fantastic drone images. Thank you very much for helping us get this off the ground – we hope it will engage people with the Cathedral’s history for many years to come!”

Terrain surveys prides itself on customer satisfaction & is proud to have been part of helping St Albans Cathedral launch its fund raising programme in order to preserve its valuable heritage.