Laser Scanning of Nelson’s Column for New Hat

At 5am on the last day in August, over twenty colourful hats appeared on statues throughout the capital. The highest, on Nelson’s column, was craned into place during pitch darkness following weeks of preparation, including wind-tunnel tests and a secret laser scan survey which accurately measured the statue’s hat size.

The event was organised by the Mayor of London and Grazia magazine to celebrate London festival 2012 and to promote British Millinery talent. Following months of careful planning, hats were installed overnight on statues from Marble Arch to the Bank of England, to give tourists and Londoners a colourful surprise on the first Tuesday of the Olympics.

The hat itself, complete with Union flag and a replica Olympic torch, was designed by Britain’s oldest hatters, Locke & Co; famous for making Lord Nelson’s original bicorn hat in 1803. Whilst the hatters used traditional techniques, a team of experienced land surveyors from Terrain Surveys Ltd applied the latest technology to measure the statue from a distance. A laser scanner was used to capture a 3D model of the statue of Nelson with millimetre accuracy, from vantage points on roofs surrounding Trafalgar Square, including Canada House and the National Gallery.

According to John Lane from Terrain Surveys Ltd. “Gaining accurate measurements would have been impossible using traditional surveying techniques. This new equipment gives a completely accurate model of Nelson’s head in precise detail, even though the statue is up to 90m away from the scanner. During the scanning it was stipulated that we avoid directing the laser beam below the foot of the statue where there were a pair of kestrels nesting. ”

Measuring the statue was part of a secret operation organised by Blonstein & Associates, the production company for HATWALK. From the 3D digital model delivered by Terrain Surveys, a full size plywood bust was produced and installed in a wind tunnel to test that the hat would withstand the worst of British weather.

The above image of Nelson’s statue was produced by creating a 3D meshed model from the pointcloud data. The model was then imported into 3D Studio Max where lighting and effects were applied before rendering.