STRATA
Client
Isle Royale, MI
Location
1855
Year Built
The Rock Harbor Lighthouse sits on the rugged south shore of Isle Royale, reachable only by seaplane and boat. To support NPS structural repairs, STRATA needed complete visual and geometric documentation of the structure, from its lantern and exterior envelope down to the narrow wood spiral stair inside. RC Monkeys delivered a comprehensive as-built set and a functional Revit model, and identified a measurable 2.8° tower lean that informed TYLin's structural assessment.
[ SERVICES ]
Laser Scanning
3D Virtual Tour
Photogrammetry
Revit Modeling
[ delivered value ]
2.8° tower lean, precisely measured for the first time
Design-ready 2D and 3D assets from a single field mobilization
Reduced dependence on incomplete record information
Visual access to areas with no clear line of sight or too elevated for standard inspection
[ challenge ]
The lighthouse's remote island setting meant detailed planning and execution, because return trips could blow the budget and derail the schedule. The 50-foot tower shows a visible lean to the northeast, a known concern since the 1950s, but existing records lacked the dimensional precision needed for structural evaluation. Inside, the spiral staircase, constructed entirely of wood, had suffered chronic rot and failure, and limited documentation meant the design team had little information to work from. The surroundings offered few reference features for scan registration, requiring a planned target placement strategy to ensure specified measured accuracy.
[ SOLUTION ]
With no opportunity for a return trip, the capture plan had to deliver complete coverage in a single mobilization.
Laser scanning, photogrammetry, and 360 photography documented 100% of the interior and exterior. Dozens of spherical targets placed at the base and top of the tower addressed the lack of registration features, maintaining specified accuracy across the full dataset.
A web-hosted mesh model and georeferenced aerial and ground photography gave the team visual access to areas with no clear line of sight or too elevated for standard inspection.
The 3D virtual tour was delivered within two days of capture, giving the consultant team remote access to the lighthouse before their first design site visit. A photorealistic point cloud, orthographic elevations and a Revit as-built model provided design-ready references. Additionally, the scan data confirmed a 2.8° tower lean, replacing visual observation with a precise, measurable baseline for TYLin's structural evaluation.
The full dataset was delivered in 10 days.
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