1. A method for comparing an as-built state of an industrial plant and an associated three-dimensional computer aided design (3D CAD) model of the industrial plant, comprising: separating components of the industrial plant into reliable components and unreliable components; obtaining digital images of the unreliable components in the as-built state of the industrial plant; superimposing the digital images of the industrial plant on the 3D CAD model of the industrial plant; for the unreliable components, comparing the as-built state of the industrial plant with the associated 3D CAD model, based on the digital images superimposed on the 3D CAD model; and for only the reliable components having physical installations visible in the digital images, comparing the as-built state of the industrial plant with the associated 3D CAD model, based on the digital images superimposed on the 3D CAD model.