1. A method of projecting a three dimensional figure to a two dimensional figure, the method being performed by a computer, comprising: selecting, by the computer, a data set of three dimensional figures out of a stored data set of three dimensional figures, wherein the data set of three dimensional figures is related to an associated dimensional line and other three dimensional figures, wherein the data set is set in an edit mode for accepting an operation by a user; determining whether a data set of both ends of the dimensional line is associated with the three dimensional figure or the three dimensional figures, the three dimensional figure and figures being selected and being in the edit mode; obtaining two dimensional figures through performing a projection of the data set of three dimensional figures and the dimensional line onto a two dimensional plane in the case where the data set of both ends of the dimensional line is associated with the three dimensional figures.