Using a Handheld Laser Scanner to Survey Boston City Hall

March 3, 2022 GeoSLAM

An engineering company were surveying Boston City Hall, using GeoSLAM's innovative technology, to aid the modernisation of the hall.

Mapping an Iconic Landmark

Location: Boston, USA | Scan time: Approx. 20 minutes per scan | Size: Over 1 million sq/ft | Scanned: Boston City Hall | Industry: Surveying

Boston City Hall was built in 1968, to help boost the city’s economy after years of stagnation. The building and surrounding plaza sought to modernize the city’s urban centre, reinvigorating the run-down neighbourhood of Scollay Square.

Despite the public investment project being welcomed by the people of Boston, the buildings ‘brutalist’ style of architecture created debate amongst the locals, with some suggestions you either love or hate the concrete design. In spite of the concerns from the public, the city hall has been home to the mayor of Boston and the city council for over 5 decades, and the ‘brutal’ style of architecture has become part of Boston’s rich history.

To encourage more people to use Boston City Hall and to increase accessibility, it was decided in 2017 that the City Hall would be renovated to serve a more modernized purpose. The infrastructure upgrades include better access to utilities, plants and fountains in the plaza area, with the intention of encouraging more people to visit.

The Horizon was a gamechanger...it's just amazing in terms of the scanning distance, power of the sensor and the ability to easily capture the entire plaza.

Peter Garran and his team, from Aerial Genomics, were appointed by The City of Boston and Sasaki with the task of scanning both the interior and exterior of the City Hall, in anticipation of the renovation project. Spanning 9 floors and housing multiple individual rooms, as well as a busy plaza area, the task of mapping the building threatened to take several months to complete. Also, the City Hall is an active office that contains confidential rooms and Aerial Genomics did not want to disrupt everyday operations too much. Considering their options, the team decided the fastest and most cost-effective way of mapping the building and its surrounding area would be to use mobile Lidar scanners.

They chose a ZEB Horizon to scan the exterior and inside the Main Hall. The ZEB Revo RT was used to map the building's vast interior. These scanners were chosen due to their speed, accuracy and mobility. By simply walking around the building, Peter and his team captured the large layout, saving them time.

As they were scanning during the pandemic, it was key for Peter and his team to spend as little time as possible in the building and compared to other scanning methods, GeoSLAM’s scanners were able to deliver on that goal. With the ZEB Horizon, Aerial Genomics captured both the exterior and interior of the Main Hall in just 4 scans and in less than 2 hours. This scanner was specifically chosen to scan the Main Hall due to its 100m range being able to capture the high walls. To help combat getting in the way of the City Halls’ day-to-day business, the team were given limited amounts of time in the evening to scan a multitude of rooms inside the Hall. Using the ZEB Revo RT, the team could scan the almost 1 million square feet interior, in just 4 nights, consisting of 5 hours each night.

The scans were processed using GeoSLAM Hub and merged to create one point cloud, by Aerial Genomics. The manoeuvrability, ease of use and accuracy that the ZEB scanners provided meant the data collected was ready within a week, to be created as a BIM model to send to the architects. The simple, easy to use solution meant the architects could start thinking about the redevelopment and renovation, without the need to visit the hall during a pandemic. The final BIM model, created in Autodesk Revit, is still referred to today.