A method of generating three-dimensional composite digital images can serve multiple purposes in technical illustration. The method was devised to accelerate and facilitate the design of new electric lights and receptacles for large buildings, and can just as well be applied to the design, redesign, and analysis of other buildings and equipment.

In the original application that motivated the development of this method, it would have taken an excessively long time to make traditional-style drawings by the traditional method, because of the complexity of the facilities. Accordingly, a major element of the method is that one makes detailed three-dimensional drawings of only those parts of the facilities and equipment that are to be modified. Data on the parts not to be modified are acquired by photographing the facilities in their present state by use of a digital camera and, if necessary, retouching the digital photographs by use of commercial software developed for that purpose.

Computer-aided-design (CAD) software is used to generate three-dimensional computational models from the new drawing data. Materials are assigned to the surfaces of the models. The models are rotated to match the perspective and lighting of the digital photographs, and are then composed onto the photographs. If necessary, hidden-line isometric profiles are created from the three-dimensional models and rendered as details in drawings. The models are created only once and are reused in different views; they can also be reused on different projects.

This method greatly reduces the amount of time needed to make drawings for modifications of facilities. In this method, unlike in the traditional method, little or no time is spent in research of prior drawings or in measuring dimensions. The composite images generated by this method have higher levels of detail and are easier to understand, relative to traditional drawings. An additional and unobvious advantage afforded by these images is that they can reveal conflicts in original designs of facilities and equipment. The composite images can be printed in color, generated as dozens of different file formats [including portable document format (.pdf)] that can be transmitted by electronic mail, incorporated into CAD drawings, or documents generated by word-processing software, and/or attached to MAXIMO work orders.

This work was done by Arlene S. Reese, Thomas Bigelow, and Robert C. Kemmerling of United Space Alliance for Kennedy Space Center.