Onyx is a proposal for a small scale concrete kiosk located at the Botanical garden, Gothenburg. It recreates the sharp and almost dangerous language of rock formations, yet completely friendly for human beings. Visitors may enter the kiosk during a cold winter day with hot cup of mulled wine and experience the space. Aggregated out of 121 custom made concrete blocks, the installation offers functionality as seating and shelter. By a computational implementation of an aperiodic space partitioning algorithm, only 4 moulds for casting of the concrete blocks are being used for the whole kiosk without compromising the random and dynamic aesthetics of rock formations.

Horizontal surfaces in different heights and with varying areas offer plenty of opportunities for users to interpret the possibilities of the kiosk themselves. Due to the aperiodic tiling system the kiosk appears completely different from various angles. The three openings (door and windows) act like passage for people, light and communication.

 

In order to create a three-dimensional aperiodic pattern of polyhedrons a technique called Danzer packing has been adopted. It is based on an iterative subdivision of four specific tetrahedrons. For every subdivision the same set of tetrahedrons are obtained, but scaled with a factor equal to one divided by the golden ratio.
To perform the subdivision of the danzer tiles in an automated fashion, a custom component for Grasshopper3d was created. It consists of roughly 600 lines of C# code and produces a mesh of the tetrahedrons and their corresponding type. The input arguments are the starting tile, the level of subdivision and a scale factor.

The colour of the boulders represent the four different moulds they were cast from. By placing “subtractors” – smaller tetrahedrons derived from next subdivision generation in the moulds – it is possible to create all these unique boulders in just four moulds.

Three subdivision levels were used for different purposes; First level, N, was used for the kiosk as a whole. The second scale, N+1 was used for moulds while the third scale, N+2, was utilized for the subtractors.