In geometry, a point reflection or inversion in a point is a type of isometry of Euclidean space. An object in 2D which is invariant under a point reflection, possess point symmetry; if it is invariant under point reflection through its center, it is said to possess central symmetry or to be centrally symmetric. In 2D, a point reflection is the same as a rotation of 180 degrees.

20160119_12531320160310_14173620160314_193352 20160119_130438 20160119_131553 20160119_132232 20160119_132517 20160119_142257 20160120_103908 20160120_120355 20160121_102203 20160121_122619 20160121_134742 20160121_141511