The Listening Ears Laser Scanning

The Listening Ears also known as 'acoustic mirrors' located in Denge near Dungeness in Kent are large concrete structures designed as an early warning system for Britain to detect enemy aircraft. They were built in the 1920's and are the best known of the various acoustic mirrors built along Britain's coast. The mirrors consist of two huge bowls, 20 and 30 feet high, and a 200 feet long acoustic 'mirror' wall, shaped like an amphitheatre to focus sound which is one of only two such structures left in the world. These remnants of a long gone, yet innovative technology stand out stark against the landscape. 

English Heritage decided that these important structures needed to be fully recorded for historic purposes as well as to monitor for structural change and also to gauge the effectiveness of proposed repairs. 

Objective
A fully detailed survey of the Listening Ears was required due to the unstable nature of the gravel island and the exposed location resulting in an uncertain future for these structures without positive plans to preserve them. 

A photographic survey of the structures was completed by English Heritage at the same time as the Laser Scanning to provide a complete record. 

Services Provided
3D Laser Scanning was undertaken over 2 days from a variety of locations to reduce the chance of any data voids. 

The point cloud data was processed to separate out and clean the structures ready for meshing. 

Deliverables
A detailed 3D mesh was produced of both the front and back of each structure using Polyworks. The data was provided as both ascii files of the scan data and as meshes of the structures. 

The 3D data provided the record English Heritage needed to assess current decay of the structures as well as determine how effective repairs would be.

Key Successes
This project is a good example of where scanning is highly beneficial for unusually shaped structures, as the complex 3 dimensional shapes cannot be fully captured by other techniques. As a record, the scan data is an excellent snapshot in time and also provides a comprehensive record of a lost technology and human ingenuity.

For further info on our 3D Laser Scanning Services please click here
To contact us please click here