Alternative approaches to three-dimensional (3-D) reconstruction by employing the concepts of “system identification” and “communication systems” based on structured light patterns are proposed. In addition, a sampling criterion of the light source is derived in the case of using multiple projectors because 3-D reconstruction sometimes employs multiple viewpoints (cameras) and multiple structured light sources (or projectors). To reformulate a reconstruction problem, an input–output (I/O) system theoretic is adopted, and camera(s) and light source(s) that are located at different positions are defined as the output and the input, respectively. Akin to the system identification problem, the ratio of an output to an input, the “system function,” is defined as a 3-D measurement result. Alternatively, the reconstruction work can employ the concept of the “modulation and demodulation theory,” and the reconstruction work can be reinterpreted as an “input estimation problem.” This contribution chiefly deals with approximate reconstruction results that are sufficient for practical applications, such as 3-D object detection, clarification, recognition, and classification, rather than a perfect 3-D reconstruction itself. To that end, the development of an efficient and fast 3-D imaging system framework is proposed.