A method and system of determining the physical dimensions and configuration of a structure or system as a precursor to the design of modifications of the structure or system by analyzing hidden objects within the structure or system is provided. The method includes accessing the structure or system prior to the modification for preparation of the modification; scanning the structure or system with an x-ray backscatter unit; collecting data from the x-ray backscatter unit and combining and reconstructing the data into a 2-D, 2-D panoramic or 3-D data set; producing surfaces and structures of the hidden objects from the data set; and tying the surfaces and structures of the hidden objects into a pre-existing coordinate system of the structure or system creating a 3-D model.