 Obelisk in the form of a ‘stretched’ tetrahelix. |
 Leaning and branching obelisk in the form of a tetrahelix.  Space frame trellis with a double cantilever, analogous to the branching of a tree. |
Note that geodesic domes with a fourfold symmetry can be augmented, analogous to orthogonal plane tessellations.
Twin Domed Pergola
Twin Domed Pergola
Twin Domed Pergola
A fourfold symmetry adaptable to plans with right angles, which is the norm.
Geodesic Dome
Geodesic Dome
These surfaces are referred to as Schwarz’s periodic minimal surfaces, in honour of the mathematician H.S. Schwarz who first explored them in 1867. These periodic minimal surfaces can be tessellated into hexagons and heptagons consisting of equal length edges, The design of this highly efficient structure was inspired by recent research in Fullerenes.
Saddle Shaped Pergola
Saddle Shaped Pergola