Page 186 - Forensic Structural Engineering Handbook

THE FIRST STEPS AFTER A FAILURE 5.19

FIGURE 5.14 This digital 360 degree panoramic Laser Image™ is photo-realistic, and can be
zoomed and panned. (Courtesy of Quantapoint, Inc.)

for structures with difficult geometries. This technique was used to analyze the spiraling
structure of the Guggenheim Museum in New York City. (See Fig. 5.15.)

FIGURE 5.15 Laser scans of the Guggenheim Museum were used to create a
finite element model that was used for a structural analysis of the building.
(Courtesy of Quantapoint, Inc.)

3D Photography. Software is available to convert 2D images into 3D models using prin-
ciples of photogrammetry. Models created using this technique do not have the precision
of laser scanning, but may be useful for visualization. The main advantage of this technique
is that no special field equipment or personnel is needed, since photographs can be taken
with an ordinary camera. In many instances, the technique can be applied to used “retroac-
tively,” to photographs that were not taken with this technique in mind.
This technique was used to create a 3D model of a collapsed work platform. The col-
lapsed platform shown in Fig. 5.16a was photographed from various angles using an inex-
pensive digital camera. At the time that it was photographed there was no plan to create a
3D model of the platform. Four of these images were loaded into a photogrammetric
software package. Distinct points, such as corners of objects, that appeared in multiple
views were marked and labeled within the software. The software then determined the