Geometric Survey Through Laser Scanning of a Historical Building In Alberta

Abstract

Advances in technology have provided engineers with the tools to conduct geometric surveys faster and more precisely. Laser scanning has bridged the gap between classical geometric data collection and modern technology. However, limitations exist within laser scanning. Users need to be aware of these limitations, like obstructions, cost, scanning distances and their effect on accuracy, before applying the methodology, especially when evaluating existing buildings. A case study was conducted on a historical site in Alberta to investigate the feasibility of using such technology to assess the safety of an existing structure. The assessed building is the absorption building, built in 1930 at the Turner Valley Gas Plant, a National Historic Site. This building is constructed from different steel sections connected via steel nails randomly chosen in size, number, and location by the contractor. High vaulted ceilings, obstructions, and missing members are common within the building which increase the complexity of surveying it. Two cloud models created from different data sets and products were compared. The same post processing register was used for comparison. Conclusions derived from the results are that the methodology is only useful when used appropriately, that scan quantities and overlap are required to obtain adequate data and that post-processing factors like decimation can result in a loss of required topographical data.