In homothety, each point P of the set S of all points of unextended space is carried into the point P1 of S collinear with P and a fixed point O of space, and such that , where k is a nonzero real number. Note that OP1, OP denote the sensed magnitudes of OP1 and OP.

For a detailed description of the object created Q, use the routine detail (i.e., detail(Q))

The command with(geom3d,homothety) allows the use of the abbreviated form of this command.