Photo-based 3D modeling of construction resources for visualization of operations simulation: Case of modeling a precast façade

3D models of building components or construction resources have been largely created by computer-aideddesign (CAD) or by proprietary code for virtual reality development. Such 3D modeling methods entail accurate definition of points, lines and their relationships in the spatial coordinate system. Unlike CAD modeling, the surveying technique of photogrammetry takes a completely different approach by deriving metric information about an object through measurements conducted on photographs of the object. The very basic technique of photogrammetry is effective and computationally simple. With much less efforts, digital cameras and photogrammetry software have made possible 3D reconstruction of an object in digital form (coordinates and derived geometric elements). The resultant 3D models may well satisfy application needs in construction simulation visualization. In this paper, we introduce computing algorithms of photogrammetry and present an application of modeling a precast facade in 3D based on digital pictures taken at a building site.