Public Interactives: Spectrum and RiverFire

I’ve had a long interest in projects that combine aesthetics and technology into interesting physical sites and installations. Inspired by projects like Munehiko Sato’s ‘Constellation of Departure and the works of Jim Campbell, I describe below ideas for two interactive installations designed to be shown at the Northern Spark nuit blanch festival.

Spectrum: The Shape of Sound

Spectrum will be a real-time sonic visualization installation that allows participants to literally see and play with sound. It invites audience interaction through a three dimensional “audio-pixel” display.

An audio pixel is a device that both detects and visualizes ambient sound. An array of hundreds of these placed three dimensionally creates an interactive volumetric sound space. When an audio pixel detects sound it visualizes it using the led based on intensity and frequency of the sound source. Lower frequency sounds, for example, can create warmer colors than higher frequency sounds. Ambient noise of street can generate random hues. Distance from the sound source to audio-pixels also modulates the intensity of the led lights. To enhance the visualization, lights triggered by sound waves will gradually fade out if there is no sound creating a persistence of vision of the shape of the sound.

Participants can walk in and around the sculptural display, making or playing sounds to interactively create three dimensional patterns of sounds as dynamic visual forms in space. In doing so, the work  hopes to delight the senses and expand the spectrum of sensory perception.

Spectrum for Northern Spark will be situated on the west side of Stone Arch Bridge as show below. The overall dimensions of the installation for Northern Spark will be 60 ft long,  30 ft in width, and 10 ft in height. A vertical grid of audio pixels will be space 5 feet apart in the overall matrix. This allows room for viewers to walk inside and through the structure, interacting with it from multiple angles.

The location near the Stone Arch Bridge affords both a great view  and generates awareness and traffic for the work.

For ZERO1, the platform of Spectrum will accommodate the Imwalle Space on South First Street at the intersection with Paseo de San Antonio. This is a large space that will accommodate the scale and unique spatial nature of the piece as well as a high traffic location that will attract participants.

Each battery powered “AudioPixel” will consist of a RGB LED driven by an Arduino micro-controller with an attached microphone. As shown above, these devices will be suspended from a the 60ft by 30ft by 10ft. Participants are encouraged to speak, clap, or sing to generate the sound that will be visualized in the three dimensional matrix of lights. Additionally, a high fidelity stereo sound system and music player will be installed allowing participants to tinker and experiment with visuals by choosing from the music player a selection of sounds to be played and visualized in the sound structure.


RIVERFIRE will be a real-time visualization of audio and human activity projected as a data layer directly over the waters of the Mississippi, using the river itself as the projection surface. It explores how the river and land are intertwined in an energetic dance. In pursing these goals, the work hopes to be impactful by revealing the dynamism of the Minneapolis region and the energy of nuit blanch itself.

Imagery of historical photographs showing the evolution of Minneapolis will float as ethereal forms undulating with the motions of the river water. An array of microphones installed along the Stone Arch Bridge will allow participants to interact directly with this data layer. Audience members speaking or singing into the microphone will create a ripple effect in a sonic visualization projected directly onto the waters of the Mississippi beneath the bridge. Flows of people across the bridge will also drive the river visualization. The ambient sound field from this traffic will produce streams of particles like fireworks flowing on the river. These moments of interaction will capture the inter-connection and dynamism of different flows in Northern Spark and Minneapolis: flow of data, flow of water, and flow of people.

Ambient sound will be delivered wirelessly to receivers and mixers connected to two computer stations running custom visualization software. These computers drive two high output projectors mounted on the edge of the bridge and aimed onto the waters south of the Stone Arch bridge. The projection area will cover a 200 ft by 80 ft surface on the water.


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