The Reality Capture of Ellis Island

From field to office archive

The challenges of digitally capturing the three sizeable, interconnected hospital buildings of Ellis Island from the exterior included the structures’ irregular footprints; large aged trees in close proximity; inadequate exterior sight lines to rooftops due to a nearby sea wall; and ongoing construction to repair damaged infrastructure from Hurricane Sandy.

The interior spaces’ also had challenges, including the hospitals’ four floors and complex attics totaling 11,148 metres of complicated, disconnected mazelike corridors and spaces. Adding to the challenge, decades of deterioration needed to be worked around, including collapsed walls, unpassable stairs, and no working lighting despite boarded windows, which lead to an extensive setup of interior lighting rigs being used throughout scanning.

In years past, the 11,148 metres of interior floor space and complex exterior footprint was a daunting scope. The ScanStations’ extended target acquisition ranges were pushed to the limits to keep a tight, accurate control network around the large structures while interior efforts focused on major corridors, large spaces and stairwells to build out the key interior spaces and link the floors in the digital point cloud model.

“In the hundreds of surveys I have performed for the NPS, I would deem this the most challenging due to this disjointed nature of interiors and the few access points and sight lines to the exterior,” said Davidson.

With the newest ScanStation P40 in the HDP’s arsenal, blazing fast scanning speeds are providing an opportunity to capture a far greater amount of the 250 interior rooms. Leica Cyclone, the 3D modelling software, continues to be the backbone of data processing for photo-texturing and the registration of years’ worth of HDS data, controlled in a survey network.

From Cyclone, in addition to the virtual tours and other interpretive media, the data is migrated to AutoCAD via Leica CloudWorx software in order to create one of the pillars of the HDP - 2D measured architectural drawings of great accuracy and detail. Such drawings were historically created entirely by hand-measurements. Although hand methods are still used by the HDP to create complete parametric 2D drawings by filling in data gaps (“shadows”) in the scans (for example, where the details of window frames were blocked by boarding), the laser scans create the baseline of accuracy key to archival records that will guide future rehabilitation or mitigation against possible damage.

Davidson concludes, “It would have been next to impossible to accurately map the interior spaces, let alone the complicated roof lines with traditional survey methods. While creating the final archival drawings and records to be delivered by the HDP, knowing the precise relationship of building components to one another eliminated guesswork and saved valuable time in the field and office, allowing us to focus our energy on the significant and unique detailing of the Hospital Buildings. To me, laser scanning rocks!”

Back to Reporter 75 article overview

Story: The reality capture of Ellis Island
Chapter 1: Hurricane takes a hit on history
Chapter 2: Reality capture for rehabilitation and interpretation
Chapter 3: From field to office to archive