Stereometric forms in architecture derives from stereometry, the art or science of measuring solids, a branch of geometry dealing with solid figures. This in contrast with Planometric drawing, geometry of flat planes. Stereometrically pure forms would include the cone, cube, pyramid, and sphere, but is informally extended to all regular three dimensional solids. These were important elements in Neo-Classicism, but remain one of the principal elements of architectural design.
Drawings by Frank Gaylard from: Fisher, Roger C. 1992. Visual Lexicon of the South African Dwelling. Cape Town: Unibook. p, 8-9.