Overlaying Digital Images with 3-D CAD to Document as Built Construction

by Karl A. Raynar, Pennsylvania State Univ, University Park, United States,
Gary R. Smith, Pennsylvania State Univ, University Park, United States,

Document Type: Proceeding Paper

Part of: Computing in Civil Engineering


A persistent problem in construction has been documenting changes which occur in the field and preparing as-built drawings. The accuracy and completeness of field measurements is often questionable. Combining computer vision technology with 3-D CAD to produce as-built drawings offers a potential solution. 3-D CAD is being used increasingly as a design tool for construction projects. CAD users can look from any viewpoint in any direction and create perspective images of the model. Digital images can be used to provide accurate information needed to document as-built construction and update the CAD model. Overlaying processed digital images with perspective images of the CAD model, the actual construction of the physical plant can be compared to the original design of the CAD model. This will permit the CAD user to identify differences and update the CAD model. This paper describes the relationship between 3-D CAD and computer vision, of which digital image processing is a part. It also presents the work which has been done to process a digital image of a construction scene and calibrate it to determine the camera viewpoint and direction. The overlay process is demonstrated.

Subject Headings: Imaging techniques | Computer aided design | Construction management | Structural design | Model accuracy | Physical models | Signal processing | Graphic methods

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