A visitor at the threshold: the projected mesh rises across the door and over their body.
04  /  Installation  /  2026

Threshold Apparatus

An interactive moving-image study of bodily proximity: a sensor reads how close you are to a doorway, and a projected mesh wakes, deforms and settles as you approach, pause and pass.

Year
2026
Type
Interactive installation / Moving image
Location
Doorways and corridors, projection
Tools
Arduino Uno, ultrasonic sensor, Processing, projector

Everyday life is full of moments between entering and not yet entering: a pause at a doorway, a slower step at a corridor corner, a moment of hesitation before a glass door. They suggest that a spatial boundary is not only a static element, but something perceived and activated by the body’s approach, pause and passage.

The project asks how interactive moving image can make that threshold visible. Projected onto real transitional spaces, the image stops being something to look at and becomes part of the boundary itself: a spatial skin that responds to the body.

5states of the projected surface
5bodily actions mapped: approach, pause, proximity, crossing, occupying
1ultrasonic distance sensor
Real timeArduino to Processing over serial

Design process

  1. Everyday thresholdsDoorways, corridors, glass doors
  2. Threshold as transitionApproach, pause, crossing
  3. Body-threshold matrixFive actions, five responses
  4. Sensor to imageArduino to Processing
  5. A responsive spatial skinProjected onto the doorway

Approach, pause, pass

Scroll to walk up to the door, drag to turn it

The installation rebuilt as a live diagram: a visitor walks toward a doorway, the ultrasonic sensor above it reads the distance, and the triangulated skin projected on the wall wakes, peaks at the threshold and settles after they pass.

    Loading model…

      Research

      In architecture, a threshold is not simply a doorway or an edge but a transitional condition, connecting inside and outside, open and closed, public and private. Its meaning lies less in form than in how it organises action and perception.

      As one approaches a doorway, the body slows; before a transparent boundary, one checks whether entry is possible; in a narrow passage, posture adjusts. Space is not passively used but continuously formed through its relationship with the body.

      Body-threshold-space relation matrix: approach, pause, proximity, crossing and occupying, read as movement, threshold state, perception and spatial response.

      So the project should not simply be an interactive video. Moving image acts as a visual skin; bodily distance, movement, pause and orientation are the perceptual data; the image is a threshold field that deforms, expands or contracts; and the physical space is the framework in which meaning is made.

      The logic of responsive spatial generation, in four layers: visual skin, perceptual data, threshold field and spatial framework.

      Sensor to image

      An Arduino reads distance in real time through an ultrasonic sensor and sends it to Processing over serial. Processing maps the distance to an interaction value that drives mesh displacement, colour, opacity and interference.

      The value is smoothed, so the image responds gradually rather than switching on and off: the threshold reads as a continuous spatial event.

      Interaction flow, State 0 to State 4: idle range, detection, mid-range response, peak threshold and residual closure.

      Scroll through the five captured states

      The five states as captured from the Processing sketch: still while no one is near, waking as a body enters the sensor’s range, peaking at the threshold and settling into a residual trace after they leave.

      1. 01Dormant boundaryBeyond the sensing range, the interface stays still.
      2. 02Initial activationA body enters the range; a subtle undulation appears.
      3. 03Spatial negotiationMid-range: the surface reshapes with every movement.
      4. 04Threshold intensificationAt the threshold, deformation and interference peak.
      5. 05Residual closureAfter departure, the trace fades and settles.
      Dormant boundary: Beyond the sensing range, the interface stays still.
      Initial activation: A body enters the range; a subtle undulation appears.
      Spatial negotiation: Mid-range: the surface reshapes with every movement.
      Threshold intensification: At the threshold, deformation and interference peak.
      Residual closure: After departure, the trace fades and settles.
      Testing the sensor against the live sketch.
      Arduino Uno and HC-SR04 ultrasonic sensor.

      In the doorway

      The installation is projected onto real spaces with transitional qualities, such as corridors, entrance halls and stair landings, and is activated by the body as it approaches. Transience, responsiveness, corporeality and threshold come together in one dynamic boundary.

      The projection wrapping a doorway and the corner of a room.
      A silhouette beside the projected field.
      The surface at peak intensity, with interference lines across the wall.
      The dormant white mesh across the door and wall.
      Detail of the projection on the door frame.

      Presentation boards

      Threshold Apparatus
      Inspiration and background
      Research
      Design framework
      Final outcome