4.1. Study sites and data acquisition
We conducted a pilot implementation of the proposed approach for
Engineering Research Park at Yonsei University. The building, including
a variety of research and education support facilities has a total area of
69,770 m2. We selected two specific places, a corridor (Fig. 7-a) and
the main atrium (Fig. 7-b). The corridor is a relatively simple structure
consisting of a long aisle with several elements such as windows,
doors, and stairs. The width and the total length of the corridor are
about 2.4 m and 72 m, respectively. By contrast, the atrium is a complex
structure including a huge space with many columns and walls. It also
includes an overbridge connecting two sides of the third floor, and the
roof is constructed of a steel frame and glass. The size of the atrium is
about 45 m long by 18.5 m wide.
Our work began with a scan of the two structures using two laser
scanners, Leica ScanStation 2 and FARO Focus 3D. ScanStation 2 acquires
a maximum of 50,000 points per second in the “time-of-flight” mode.
The maximum scan range is about 300 m, suitable for acquisition
of the data of a large, open area. Focus 3D is a phase-shift laser
scanner boasting a much faster scanning speed (1,000,000 points per
second) but offering only a relatively limited maximum scan range of
120 m. In the experiment, ScanStation 2 was used first, after which
Focus 3D was employed to collect the point cloud data of occlusion
areas. The scanned point cloud data was imported to commercial software Leica Cyclone 8.0 for registration and removal of noise. Fig. 8
shows the merged point clouds of the two structures after removal of
the noise.