Sova Surveys in Bath, England, was recently contacted by a return client to produce a BIM model of Margam Castle in Wales for a refurb project. The structure is a look into the past — a historical landmark and a “timeless, classic Tudor-style building sometimes used as a set for period pieces,” says Sova Surveys director Jared Matthews.
Sova’s workflow, in contrast, feels a lot like the future.
Classic challenges
Sova knew their work was cut out for them. Margam sprawls over 25,000 sq meters and seven floors. As you might expect for a structure roughly two centuries old, it includes complex and ornate features like a central staircase. It also has several tricky areas where it’s tough to maneuver a scanner.
As if that weren’t challenging enough, the castle is situated in a public park. Though most of the structure would be closed to visitors during the survey, the public toilets and bike-rental structures would be left open for business. Sova needed to finish capturing these high-traffic zones within two hours to reduce disruption to the castle’s business.
And since the deliverables would be used for a historical refurbishment project, the accuracy requirements were high. Sova would need to deliver a BIM model at LOD200 for most of the castle and LOD400 for significant features like the central staircase.
The classic workflow
In the past, Matthews would have captured a structure like Margam Castle using the industry’s standard scan-to-BIM workflow.
He and his team would establish a control network with a total station. Then, they would capture with a terrestrial laser scanner (TLS) and take 2D photos with a smartphone. Once they returned to the office, they would register the scans together, organize the photos, and generate deliverables.
The first problem here is time. Though Sova could have finished the job with this workflow – and achieved high accuracy in the process – the work would have been very slow and deliberate. Especially considering the number of setups necessary to scan into the tricky areas to eliminate shadows caused by occlusion.
On top of that, scanning the public areas with a TLS would have taken longer than the two hours allotted per day. And that would have caused significant disruption to the client’s business.
Sova saw that they needed a different workflow.
For the complete article on this historical landmark CLICK HERE.
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