Harnessing scan-to-BIM technology on historic sites

Attucks School in Kansas City. (Image: GeoSLAM)

When it comes to renovating a building, unforeseen structural problems or lack of knowledge about the materials used can result in costly delays. Detailed site surveys help to highlight these issues before work begins — and digital technology is playing an increasingly important role in identifying them.

The GeoSLAM ZEB-REVO. (Image: GeoSLAM)

A project undertaken at a 112-year-old school highlights the advantages of using 3D mobile indoor mapping for rapid and simple site surveys.

“The beauty of scanning an historic building is that you find yourself delving into the stories behind its life,” said Stuart Cadge, sales and marketing coordinator at GeoSLAM. “As you peel back the layers you discover how the building has been used and altered over many decades of use.”

This was certainly the case at the Attucks school in Kansas City, Cadge said. The distinctive red-brick building was designed by local architect Charles A. Smith and built in 1905. It is known for its colonial revival influences and also played a key role in the educational history of the African-American community.

Two decades later, the school was suffering from over-crowding, and Smith was asked to extend it with a two-storey wing that connected to the east façade of the building. While the 1905 building had been symmetrical, the extension changed the floor plans considerably. Nevertheless, Smith delivered a sympathetic design that incorporated some of the original architectural details, ensuring the new wing was in keeping with the building’s aesthetic.

While details of the school’s building history are available on national and state registers, it would not have been possible to uncover problems in its structural condition without an accurate survey.

A Unique Challenge

Redeveloping and retrofitting a building like Attucks requires careful planning to uncover any existing conditions in its infrastructure. Civil engineering firm BHC RHODES was tasked with providing a 3D Revit building information model (BIM) of the building. The firm decided to use lidar 3D mobile mapping technology provided by GeoSLAM to achieve this.

The extremely rapid and efficient workflow of the GeoSLAM solution meant that possible setbacks in the project, caused by weakness in the structure, could be identified in advance, helping to speed up delivery time and reduce the overall project spend.

At Attucks, there were visible signs of deterioration to the wooden flooring, as well as concerns about ceiling collapses and air quality — specifically, asbestos.

The Value of Technology

“The process of mapping a historic building can expose site personnel to a number of risks, so BHC RHODES wanted to ensure they spent as little time on-site as possible,” Cadge explained.

As well as entering the Attucks building, personnel were required to move across the site safely, climb stairs and go into places that a trolley scanner could not.

On this basis, the firm chose the GeoSLAM ZEB-REVO, a handheld, lightweight, mobile mapping scanner, which employs 3D Simultaneous Localization And Mapping (SLAM) technology. In this case, it was seen as a much more time- and cost-effective alternative to terrestrial, static or trolley-based systems.

The complete 3D scan of the building comprises four separate scans and over 160 million data points. (Image: GeoSLAM)

“The ZEB-REVO is an incredibly useful tool for indoor mobile mapping, particularly in buildings with multiple storeys,” Cadge said. “It enables users to simply ‘walk and scan’ the building, in order to generate building footprints, 2D plans, area measurements for real estate and facility management, 3D BIM models — the list goes on.”

In the case of Attucks, just four-and-and-half hours were needed to scan the whole building, with the ZEB-REVO recording more than 43,000 measurement points per second. This was helped by the fact that operation of the device requires minimal staff training.

Results

Data from the ZEB-REVO and a trolley-based scanner were registered with Cyclone 9.1.4 to a common coordinate system before being exported to Autodesk ReCap as a .pts file format. From this, data was divided into 10-GB files to be used in ReCap and Revit 2014, where a level 200 BIM model was generated. The smooth and hassle-free workflow resulted in the entire building model being completed two weeks earlier than predicted.

The Jazz District Redevelopment Corporation (JDRC) in Kansas City has plans to transform Attucks into a new community performing arts facility, with office space, paying tribute to its African-American history. By supplying the JDRC with the geospatial data, the organization was better able to understand the structural condition of the building and consider how the space could be used.

The 3D point data was used to build a level 200 BIM model in Recap and Revit 2014. (Image: GeoSLAM)

The development will form an integral part of the 18th and Vine historic district in Kansas City, known as the Jazz District. The area is recognized as one of the cradles of jazz music in the 1920s and 1940s, and a historic hub of African-American businesses.

To secure approval on the plans for Attucks, JDRC must produce detailed drawings that show what materials will be used, as well as full dimension drawings, floor plans, site drawings and elevations. In addition, it must provide details, both graphically and in written form, on what parts of the building will remain and what renovation techniques will be used.

All this might present a number of challenges, but the scans produced by GeoSLAM’s ZEB-REVO show that the existing buildings are of exceptional quality. When the project does proceed, it will be able to do so quickly and efficiently thanks in part to the speed, simplicity and ease of use of the ZEB-REVO.