Interactive Installation · 2026

Playground ( PLAYGROUND )

It began with a childhood memory — drawing on a friend's back, or on the sand, as if they were a screen. What if a screen were not a surface you look at, but one you touch, press, and disturb? Sand becomes the interface; data becomes the object.

Touch × Sand: A Physical Interface

A visitor draws on stretchable fabric with one fingertip. Beneath it, a grid of time-of-flight sensors tracks the gesture in pressure and speed. The machine retraces it in sand, then adds a few marks of its own.

A turn takes two to three minutes and runs offline. Nothing is saved. The visitor smooths the sand flat again for whoever comes next.

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[ .Reading ]

Two axes, not a picture

Nothing classifies what was drawn. The finished stroke is measured on two axes: pressure, how far the fabric was pushed down, and speed, how fast the finger moved.

Those two values pick a description for the display, and set two parameters of the reply: pressure becomes groove depth, speed becomes drawing pace.

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[ .System ]

Sensing, understanding, answering

Each sensor measures the gap to the fabric above it, so a press shrinks that gap. Position comes from combining neighbouring readings. An ESP32 runs the array; a stick PC filters the samples into one line and composes the reply; an Arduino drives the motion.

An XY gantry draws it. Two steppers carry the head, a servo sets its height. Points are interpolated so curves stay curves.

200 × 130 cm of floor, about 5 kg, 65 W from one outlet.

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SENSOR ARRAY AND WIRING UNDER THE FABRIC

[ .Process ]

From Material to Interaction

Three problems took the most iteration, all tuned against real drawings rather than in simulation: catching a light continuous press on a soft surface, keeping the reconstructed line faithful without over-smoothing away its character, and drawing genuine curves without the gantry stalling.

Skin reads touch through receptors spaced apart beneath its surface, and what feels like one continuous sensation is the body weaving those separate readings together. The sensor grid borrows that arrangement. No single sensor sees the whole gesture, and the stroke is reconstructed from what several of them register at once.

It began as coursework in Object Interaction Design at Seoul National University, taught by Juhong Park, and is being developed further for the SIGGRAPH Asia 2026 Art Gallery with Chang Hee Lee.

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BENCH TEST, CARDBOARD RIG AND LOOSE SENSORS

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[ .Context ]

What the Hands Know

It began with two games: tracing a shape on a friend's back and waiting for them to guess, and drawing in sand knowing it would be smoothed away.

A scanner and a plotter could have copied the drawing exactly. A mirror returns you to yourself; a translation risks getting something wrong, and in that risk there is the possibility of being met.

And in the end, the marks in the sand are erased — following the unspoken rule of every playground.

Next Project Chorus ↘