Imaged-based verification of as-built documentation of operational buildings

As-built models and drawings are essential documents used during the operations and maintenance (O&M) of buildings for a variety of purposes including the management of facility spaces, equipment, and energy systems. These documents undergo continuous verification and updating procedures both immediately after construction during the initial handover process to reflect construction changes and during occupancy stage for the changes that occur throughout the building's lifespan. Current as-built verification and updating procedures involve largely time consuming on-site surveys, where measurements are taken and recorded manually. In an attempt to streamline this process, the paper investigates the advantages and limitations of using photogrammetric image processing to document and verify actual as-built conditions. A test bed of both the interior and exterior of a university building is used to compare the dimensions generated by automated image processing to dimensions gathered through the manual survey process currently employed by facilities management and strategies for improved accuracy are investigated. Both manual and image-based dimensions are then used to verify dimensions of an existing as-built Building Information Model (BIM). Finally, the potential of the image-based spatial data is assessed for accurately generating 3D models. (C) 2011 Elsevier B.V. All rights reserved.