Symmetry of “Twins”

• Published in: Symmetry (Basel) 2015-03, Vol.7 (1), p.164-181
• Main Authors: Nikolic, Vladan, Radovic, Ljiljana, Markovic, Biserka
• Format: Article
• Language: English
• Subjects: Architecture; Classification; Perception; Pictures; Planes; Symmetry; Three dimensional; twins; Two dimensional; visual perception
• ISSN: 2073-8994; 2073-8994
• DOI: 10.3390/sym7010164

The idea of construction of twin buildings is as old as architecture itself, and yet there is hardly any study emphasizing their specificity. Most frequently there are two objects or elements in an architectural composition of "twins" in which there may be various symmetry relations, mostly bilateral symmetries. The classification of "twins" symmetry in this paper is based on the existence of bilateral symmetry, in terms of the perception of an observer. The classification includes both, 2D and 3D perception analyses. We start analyzing a pair of twin buildings with projection of the architectural composition elements in 2D picture plane (plane of the composition) and we distinguish four 2D keyframe cases based on the relation between the bilateral symmetry of the twin composition and the bilateral symmetry of each element. In 3D perception for each 2D keyframe case there are two sub-variants, with and without a symmetry plane parallel to the picture plane. The bilateral symmetry is dominant if the corresponding symmetry plane is orthogonal to the picture plane. The essence of the complete classification is relation between the bilateral (dominant) symmetry of the architectural composition and the bilateral symmetry of each element of that composition.