Unfinished Arch
Rafael Lozano-Hemmer
Antimodular Research
2026
Unfinished Arch is an outdoor, public sculpture installation by Rafael Lozano-Hemmer comissioned by the city of Toronto. The participatory artwork will be a 9-meter-tall incomplete arch that will extend over a prominent waterfront park with one end of the arch left suspended in the air. Visitors will be enticed to complete the arch at its floating edge which contains interactive pressure plates. When the arch is completed by a user touching these plates it will illuminate until they remove their hands.
As the lead designer of the electronic control system and software that drive the artwork I have been responsible for creating the systems that enable its interactivity. Overall, the interaction between viewers and the work is simple; when the load cell sensors - typically used in digital scales - inside the metal plates at the end of the arch register the pressure of a user's touch, the arch begins to illuminate. When the pressure is released the illumination recedes. Creating a permanent, weatherproof, interactive sculpture however, involves a set of challenges that the public should never be prompted to consider.
Custom software written in C++ and python allows for realtime data acquisition from an array of 8 load cells. The load cells are connected to a custom data acquisition board that runs on top of a Raspberry Pi 5. As the pressure readings from the sensor are recorded and processed the lighting animations update to reflect the interaction state.
Demo Videos
