Diffused Surface Illumination
Diffused Surface Illumination (DSI) uses a special acrylic surface to distribute infrared (IR) light evenly across the surface that is illuminated from the outer edges though the surface plane itself. For this a an IR LED Frame is used in combination with 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 creates a even surface illumination without hotspots.
When the user comes into contact with the surface, the IR light is scattered resulting in a blob or IR light. This light blob is seen by a IR camera and relaying them to tracking software. This principle is very useful for implementing multi-touch displays, since the light that is scattered by the user is now able to exit the acrylic in a well defined area under the contact point and becomes clearly visible to the camera below. An in-system projector is used to display visual feedback on the table surface. It is important to consider that projector lamps have a mean-life expectancy of typically 6000+ hours.
Advantages
- Unlimited number of touch points
- With a compliant surface, it can be used with something as small as a pen tip
- Is pressure sensitive
Disadvantages
- Sensitive to ambient light
- Required on site calibration
- Setup calls for some type of LED frame
- Requires a compliant surface coating (silicone rubber), sensitive to wear and scratches - no glass surface
- Cannot recognize objects or markers
Touch functionality
- Multi-touch
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