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Multitouch Terminology

Below you will find definitions of common terminology regarding multitouch displays, interaction, and hardware/software development. If you would like to add a term or have a better definition for a particular term, please leave a comment or contact me so I may update the list appropriately.

If you would like to build your own multitouch display, please view the How to Make a Multitouch Surface page.

Multi-touch: An interactive technique that allows single or multiple users to control graphical displays with simultaneous touch and movement

Dual touch: An interactive technique that allows a maximum of two simultaneous touch interactions

True Multi-touch: ‘True’ is occasionally added to emphasize that several (more than 2) simultaneous touches can be sensed. It is often used as a marketing tactic to differentiate itself from ‘dual’ (2 touch) multi-touch systems

Multi-point: An interactive technique that makes use of points of contact rather than movement

Multi-user: A device that accepts more than one user. Larger multi-touch devices are said to be inherently multi-user

Multi-modal: A form of interaction using multiple modes of interfacing with a system (e.g. touch, speech, gaze, etc.)

Tabletop Computing: Interactive computer displays that take place in the form of tabletops

Direct Manipulation: The ability to physically interact and directly manage/manipulate items in digital environment rather than through an intermediary (e.g. mouse, keyboard, etc.)

Blob: An area of interest in an image that is either lighter or darker than its surrounding

Blob Detection: Process of detecting regions or areas of interest in an image that are either lighter or darker than their surrounding

Blob Tracking: Assigning an identifier (ID) to a blob in order to track it over time

Tracker: A program that takes and filters input (i.e. camera, sensor, etc.), detects and tracks blobs, and outputs information such as location, size, and relative movement of blobs

Tangible User Interface Objects (TUIO): A protocol used for communicating the position, size, and relative velocity of blobs. It is built on Open Sound Control (OSC), which is built on UDP

Touch Event: A term used to describe when a system knows that an object has touched the multi-touch device

Gesture: A physical movement that can be sensed, and often an action assigned to it. Some common gestures are single finger panning, and two finger zoom/pinching

Sensor: A device that measures changes in an environment

ZUI: Zoomable User Interface – a user interface which is infinitely zoomable. In theory this would give you infinite workspace, but memory constrictions limit this

Diffuser: Something that spreads and scatters light. A diffuser is used in various multi-touch techniques to create even lighting

Frustrated Total Internal Reflection (FTIR): A a multi-touch technique that exploits the phenomena of Total Internal Reflection. Light within a transparent channel of low refractive index will reflect internally until an object with a higher refractive index, such as a finger, touches or frustrates the surface lighting up the frustrated area

Diffused Illumination (DI): A multi-touch technique that makes use of a diffused surface to help filter shadows (Front DI) or illuminated fingers (Rear DI) from a touch surface. Sometimes this is referred to as Direct Illumination

Laser Light Plane (LLP): A multi-touch technique that uses a laser and line generating lens to cast a beam over a touch surface.When the beam plane is broken by an object, the area is lit up

Diffused Surface Illumination (DSI): A multi-touch technique that uses a special acrylic Endlighten to help disperse even light supplied by edge lighting the acrylic. The effect is similar to DI

Stereo Vision or Stereoscopic: A two camera multi-touch technique

Zero force: Refers to the amount of force or pressure needed to trigger a touch event. In this case, ‘zero’ means ‘little’

Terms to be defined:

Infrared Illuminator
First Surface Mirror
Compliant Surface
Infrared Camera
Filter/Bandpass Filter
Cold Mirror
Hot Mirror
Ambient Light
Exposed Photo Negative
Rosco Grey
Community Core Vision
Line Generator Lens
Field of View / FOV
Computer Vision
Ubiquitous Computing
Form Factor

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