ABSTRACT
Mirror inversion adds new "folds" on a solid. Mirror inversion reverses the projection and the recess. The projection fits in exactly with the recess, as they are identical in amount with respect to the original sweep locus. The sweep locus-based method of specifying mirror plane arrangement assumes the sweep locus to be horizontal and the mirror plane to be vertical. However, the mirror plane for mirror inversion can be placed anywhere posing no problem for the sweep locus to be a three-dimensional (3D) polygonal line. A 3D sweep locus can make a more complex variety of shapes. The sweep locus is a cross, but the top and bottom are a square. At the center in the photo, the six-unit combination has two twist-closing structures where four units overlap each other at the edge. Mirror inversion is applied several times to a star-shaped, one-sheet pyramid without cut. Mirror inversion is applied several times to a simple sloping cylindrical surface.
