Abstract: A method of modeling shapes to produce output data indicative of the shapes. Each of the shapes is divided into existing shapes, and removal shapes to be removed from the existing shapes to define a final shape. The two-dimensional cross-sections of the existing shapes and the removal shapes are divided into straight lines and arcs of circles and are used to form a two-dimensional wire frame representing the two-dimensional cross-section. This wire frame is then expressed as a loop information data set that includes an aggregation of data describing the elements. Existing parts of the final shape are expressed as an existence mode, and shapes to be removed from the existing shapes to define the final shape are expressed in a removal mode. Any of the surfaces of the object outside the plane including the wire frame are expressed based on planes or curved planes. Output data representing the final shape is provided based on the loop information expressed as the existing parts and the removal parts.