1. A computer-implemented method for reducing a size of a data structure of a computer-aided design model, the method comprising: given a computer-aided design model comprised of a plurality of modeling elements, providing one or more geometric entities defining each of the plurality of modeling elements of the computer-aided design model, the geometric entities having corresponding graphical entities configured to display the computer-aided design model; for each modeling element, determining visibility of the modeling element; and producing a reduced data structure in a computer memory by storing in the reduced data structure: i) graphic data representing the graphical entities; and ii) geometric data of only certain ones of the geometric entities determined as a function of visibility of the corresponding modeling element.