INNOVATION May-June 2015
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up to eliminate unwanted noise such as pedestrians, traffic, and other unwanted points. Extraction – 3D objects such as walls, pipes, valves, steel beams, and windows are extracted from the point cloud auto- matically by software or manually by an office technician. Documentation – depending on requirements, features are represented in Building Information Model (BIM) or in a tradi- tional drawing format such as AutoCAD. The bulk of the work is being performed at the produc- tion office in the extraction stage. While the automated extraction software packages are becoming more intelligent and have increased the production efficiency, it is still quite labour intensive.
surfaces will not reflect the laser beam as well as light coloured surfaces, and with transparent objects such as windows, the laser travels through. Professionals in the architectural, engineering and construction industry should be aware of new technological solutions that are available to them and understand to what extent they will add value to their business and clients. Terrestrial laser scanning technology should no longer be regarded as an unaffordable or impractical novelty. It is a part of the technological evolution from the 2D to 3D world. George Liu, P.Eng., is a North Vancouver-based engineer specializing in surveying and geomatics. He is with Absolute Space Engineering .
A laser scanner captures point cloud data, which enables extraction and documentation of mechanical components. Limitations Like all technologies, laser scanning has some limitations. These are: • Measurements require direct line-of-sight between the scanner and the object of interest. Any stored items or unwanted features in a project area will be captured. If it is an outdoor project, laser scanning technology would not be as effective during inclement weather such as rain and snow, which will produce noise in the scan. • Measurements depend on the surface reflectivity of the object’s surface. Certain surfaces and the angle of incidence can affect measurements. For example, black
Three image variations showing an exterior office building wall. The top image is strictly laser data with the colour corresponding to the signal return intensity level. The middle image applies the true colour information collected from a TLS integrated camera. The bottom image is a 3D Building Information Model (BIM) generated from the point cloud data shown above.
M AY/J U N E 2 015
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