The spotlight behaves as if emanating from the viewer's body

Perceptio Lucis (2009, 2011)

Video projector, computer, custom software, painted wood. Dimensions variable.

Perceptio Lucis (Latin, "perception of light") is an interactive mixed reality installation in which sculptural forms cast impossible shadows as if the viewer’s body is the source of light.

The objects are geometric primitives, sculpted from wood, metal, and acrylic. As one moves around the piece, what seems to be a spotlight moves too, perfectly matching its origin to the viewer’s body – yet there is no actual light source. As the illumination moves, a changing shadow is cast; as one gets closer or farther away, the shadow contracts and stretches. Nothing in the room is physically moving, the space is minimal and quiet, and the light seems alive. This artwork is a quiet dialogue between body, self, object, and light – with the uncanny yet dynamic sensation of the rules of geometry dissolving.

Perceptio Lucis presents an experimental embodiment of the philosophical movement of Idealism – whereby reality is literally constructed by the mind of the perceiver. Phenomenalism, on the other hand, held that objects don’t exist in themselves at all, but manifest only as perceivable qualities. In this installation, the debate between metaphysical idealists, phenomenalists, and epistemologists is played out in real space. As we engage with the relation between the object, space, and our perception, we must confront how technology destabilizes the role of seeing and empiricism. In this way this piece also riffs on the history of Enlightenment, and the optimistic idea that the rational mind can shine the “light of reason” on any subject and reveal its meaning. Here we seem to be literally shining the light of perception on the object, yet at the same time we see how our point of view changes reality in front of our eyes.

This installation calls into question how light and perception usually work, a debate of profound philosophical depth yet one that any viewer of any background can experience.

installation test

The setup seems simple — physical objects sit on the ground in an empty space, and when a viewer approaches a bright spotlight turns on that illuminates it. The “spotlight” is actually virtually generated via motion tracking and software rendering. The space is minimal and quiet, and the changing light and shadow is seemingly impossible as nothing in the room is physically moving. Different forms will be situated within the space, each a pure geometric shape such as a cube, sphere, or pyramid. If other people enter the space, their own spotlight will appear, and can overlap and interact with other lights.

The work can be experienced both in physical space, with no hardware on visitors, or viewed with an AR headset in any space. The rendered image is in fact only the calculated light shape, with an occlusion aligned with the physical object on the floor, while the shadow is simply empty black pixels. In the case of the physical installation, the illusion works using an overhead video projector pointed at the floor, with a motion sensor tracking the viewer location. With headset viewing, the sensing and projection take place within the goggles.

Next version preview with hollow object

A working prototype has already been created, but never completed or exhibited. The initial tests used a Kinect for motion tracking and OpenFrameworks for rendering. However, the technology to achieve the effect has improved greatly since then and will now use better input sensing and output with Unity. This residency will improve the sensitivity and accuracy of motion tracking, increase the resolution of light and shadow rendering, and create multiple sculptural objects. A responsive soundscape will also be explored to give auditory cues and enhance the meditative atmosphere.

It is important to emphasize that this work will stand in opposition to the usual speed and spectacle of new media experiences. Quiet and thoughtful modes of interaction are increasingly rare as the flood of new technologies tends to lead into the realm of gimmicks. Art has always experimented at the cutting edge, yet it must also make us slow down and think. Perceptio Lucis will push the edge of what is possible even farther forward, while remaining focused on the human, and our interaction with the world around us.

software interface showing 3 viewers

Using Format