The All City Express (A.C.E.) was a 60 foot interactive LED installation that allowed users to paint digital graffiti on life-size virtual subway trains. Developed for the Panorama music festival, the project utilized motion capture and real-time rendering to simulate the experience of subway graffiti. Once a user finished their work, the virtual train departed the screen with the artwork applied, appearing in photo-realistic renders of New York City transit environments.

To achieve a realistic experience, the tracking system operated in three dimensions, measuring the distance of the spray can from the LED wall to determine paint spread and density. The environment presented significant technical obstacles, specifically the requirement for the system to function in direct sunlight and against the high-intensity output of the LED screen. The team deployed the PhaseSpace motion capture system, which uses active LED markers. Unlike passive systems that rely on infrared reflection, active LEDs provide unique signals that remain visible in bright outdoor conditions.

Custom integration bridged the PhaseSpace hardware with Tangible Interaction’s graffiti software. The project also featured a redundant system using live green screen chroma keying. This allowed artists to use physical aerosol cans on a green wall, with the software compositing the paint strokes onto the 3D train model in real-time. This dual-system approach ensured operational stability while maintaining the fidelity of the digital artwork within the virtual environment.