Difference between revisions of "Multitouch"
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===Front Diffused Illumination (MTMini)=== | ===Front Diffused Illumination (MTMini)=== | ||
| + | Infrared light (often from the ambient surroundings) is shined at the screen from above the touch surface. A diffuser is placed on top or on bottom of the touch surface. When an object touches the surface, a shadow is created in the position of the object. The camera senses this shadow. | ||
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| + | [[Image:frontdigraphic.jpg]] | ||
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| + | Front DI Parts List | ||
| + | * Clear sturdy surface (Glass, Acrylic, Polycarbonate, Plexiglas, etc.) | ||
| + | * Diffuser/Projection Surface (Vellum, Mylar, Lee Filter, other, etc.) *Note: The Diffuser/Projection Surface must let some light through. | ||
| + | * Infrared Camera/Modified Webcam | ||
| + | |||
| + | Pros: | ||
| + | * No need for a compliant surface, just an diffuser/projection surface on top/bottom | ||
| + | * Can use any transparent material like glass (not just acrylic) | ||
| + | * No LED frame required | ||
| + | * No soldering (you can buy the IR-Illuminators ready to go) | ||
| + | * Can track fingers and hovering | ||
| + | * An enclosed box is not required | ||
| + | * Simplest setup | ||
| + | |||
| + | Cons: | ||
| + | * Cannot track objects and fiducials | ||
| + | * Difficult to get even illumination | ||
| + | * Greater chance of ‘false blobs’ | ||
| + | * Not as reliable (relies heavily on ambient lighting environment) | ||
===Rear Diffused Illumination (DI)=== | ===Rear Diffused Illumination (DI)=== | ||
Revision as of 17:38, 13 June 2010
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Creator: |
Contents
[hide]Overview
This is a research page for all things multitouch.
Methods
Laser Light Projection (LLP)
Infrared light from a laser(s) is shined just above the surface. The laser plane of light is about 1mm thick and is positioned right above the surface, when the finger just touches it, it will hit the tip of the finger which will register as a IR blob.
LLP Parts List:
- Clear, flat surface (Glass, Acrylic, Polycarbonate, Plexiglass, etc.)
- Infrared Laser(s)
- Safety Goggles
- Line Generating Lens
- Projection Surface
- Infrared Camera/Modified Webcam
Pros:
- No compliant surface (silicone)
- Can use any transparent material like glass (not just acrylic)
- No LED frame required
- An enclosed box is not required
- Simplest setup
- Could be slightly cheaper than other techniques
Cons:
- Cannot track traditional objects and fiducials
- Not truly pressure sensitive (since light intensity doesn’t change with pressure).
- Can cause occlusion if only using 1 or 2 lasers where light hitting one finger blocks another finger from receiving light.
Frustrated Total Internal Reflection (FTIR)
Front Diffused Illumination (MTMini)
Infrared light (often from the ambient surroundings) is shined at the screen from above the touch surface. A diffuser is placed on top or on bottom of the touch surface. When an object touches the surface, a shadow is created in the position of the object. The camera senses this shadow.
Front DI Parts List
- Clear sturdy surface (Glass, Acrylic, Polycarbonate, Plexiglas, etc.)
- Diffuser/Projection Surface (Vellum, Mylar, Lee Filter, other, etc.) *Note: The Diffuser/Projection Surface must let some light through.
- Infrared Camera/Modified Webcam
Pros:
- No need for a compliant surface, just an diffuser/projection surface on top/bottom
- Can use any transparent material like glass (not just acrylic)
- No LED frame required
- No soldering (you can buy the IR-Illuminators ready to go)
- Can track fingers and hovering
- An enclosed box is not required
- Simplest setup
Cons:
- Cannot track objects and fiducials
- Difficult to get even illumination
- Greater chance of ‘false blobs’
- Not as reliable (relies heavily on ambient lighting environment)
Rear Diffused Illumination (DI)
Infrared light is shined at the screen from below the touch surface. A diffuser is placed on top or on bottom of the touch surface. When an object touches the surface it reflects more light than the diffuser or objects in the background; the extra light is sensed by a camera. Depending on the diffuser, this method can also detect hover and objects placed on the surface.
Rear DI Parts List:
- Clear sturdy surface (Glass, Acrylic, Polycarbonate, Plexiglas, etc.)
- Infrared Illuminator (Infrared LEDs, Infrared Illuminator, etc.)
- Diffuser/Projection Surface (Vellum, Mylar, Lee Filter, other, etc.) *Note: The Diffuser/Projection Surface must let some light through.
- Infrared Camera/Modified Webcam
Pros:
- No need for a compliant surface, just an diffuser/projection surface on top/bottom
- Can use any transparent material like glass (not just acrylic)
- No LED frame required
- No soldering (you can buy the IR-Illuminators ready to go)
- Simple setup
- Can track objects, fingers, fiducials, hovering
Cons:
- Difficult to get even illumination
- Blobs have lower contrast (harder to pick up by software)
- Greater chance of ‘false blobs’
- Enclosed box is required
Diffused Side Illumination (DSI)
DSI uses a special acrylic to distribute the IR evenly across the surface. Basically use your standard FTIR setup with an LED Frame (no compliant silicone surface needed), and just switch to a special acrylic. This acrylic uses small particles that are inside the material, acting like thousands of small mirrors. When you shine IR light into the edges of this material, the light gets redirected and spread to the surface of the acrylic. The effect is similar to DI, but with even illumination, no hotspots, and same setup process as FTIR.
DSI Parts List:
- EndLighten Acrylic
- LEDs
- Projection Surface (tracing paper, lee filter, geriets optitrans , etc);
- Infrared Camera/Modified Webcam
Pros:
- No compliant surface (silicone)
- Can easily switch back and forth between DI (DSI) and FTIR
- Can detect objects, hovering, and fiducials
- Is pressure sensitive
- No hotspots
- even finger/object illumination throughout the surface
Cons:
- Endlighten Acrylic costs more than regular acrylic (but the some of the cost can be made up since no IR illuminators are needed)
- Blobs have lower contrast (harder to pick up by software) than FTIR and LLP
Software
Hardware
- Sony PS3Eye
- IR LED strips
- IR lasers
