Comparison of construction photograph and VR image in construction progress

A photograph always makes an image of objects as they are without any alteration, so that a photograph is recognized as highly accurate information. Thus the photograph has been widely used as a record of site, routine work particularly for construction control and inspection. As a characteristic of photograph, the point of view for a photo image is identical to that of a VR image which can be created based on 3D CAD. In other words, matching of the photo image and the VR image provides a convenient way to examine the difference between the actual situation in a job site and the design drawing for the building. This paper suggests the method for the determination of the 3-dimensional viewpoint and the direction vector of a construction photograph to perform comparison of the construction photograph and the corresponding VR image. In addition, through a case study in which acquisition of construction photographs and comparison of construction photographs and VR images according to the elapsed time have been carried out, the validity of proposed methods has been well proved.