Contents Introduction to Surface Computing Description of MT Display Devices Various Sub Systems H/W & S/W Required Usage areas of MT Devices Practical approach to multi-touch devices.
Introduction Surface computing is the term for the use of a specialized computer GUI in which traditional GUI elements are replaced by intuitive, everyday objects. Instead of a keyboard and mouse, the user interacts directly with a touch- sensitive screen.
Description The multi-touch device is a user interface device that will allow a user to interact with a computer through use of a multi-touch display. Thus, it is a substitute to the keyboard and mouse. In this user can directly interact with the system with their fingers and not only this but with multiple touches at the same instant.
How Does a Touchscreen Work?A basic touch-screen has three main components:1. Touch sensor;2. Controller;3. Software driver.The touch-screen is an input device, so it needs to be combined with a display and a PC or other device to make a complete touch input system.
Resistive touchscreenStructureResistive touch screensconsist of a glass oracrylic panel that iscoated with electricallyconductive and resistivelayers made with indiumtin oxide (ITO) .The thinlayers are separated byinvisible spacers.
Projected-capacitive touchscreen During a touch, capacitance forms between the finger and the sensor grid.The embedded serial controller in the touchscreen calculates touch location coordinates and transmits them to the computer for processing.
TERMINOLOGY Diffuser: Screen surface for projection. IR Lasers: Laser emitting IR Beam. IR Led: Led emitting IR. Blob - A bright luminescent object Blob tracking - Assigning each blob an ID (identifier). TUIO - A protocol used for communicating the position, size, and relative velocity of blobs. (Tangible User Interface Object) CCV: An open source software for blob tracking. (Community Core Vision) MT: Multitouch
TECHNIQUES FTIR :Frustrated Total Internal Reflection DI: Diffused Illumination DSI: Diffused Surface Illumination LED LP: Led Laser Plane LLP: Laser Light Plane
PRINCIPLE OF WORKING Mesh of IR is generated on screen. Frustration is created on the surface if touched. Detected by the camera. Blobs are created and sent to tracker. Tracker communicates with application.
Building LLP Set Up Table with glass top. Camera (PS3 eye/ MS Lifecam) Projector Mirror Four 780 nm IR lasers Four Line generators 89 degree each Rosco grey/Tracing paper USB cable for powering lasers Under exposed – undeveloped negative roll Cello tape/knife/wire/insulating tape..etc.
Input Subsystem: The Camera We are using a simple web camera easily available in the market. It can be made capable of detecting IR by simply removing the filter from the lens
The Projector A rear projection setup allows the projector to be placed inside the multimedia table. However, with the size of the multimedia table in mind, there is a strict requirement on the “throw” distance of the projector. An extremely short throw distance projector was found to overcome the problem.
Output Subsystem A diffusion layer is needed to provide a surface for the projected image to be displayed. To diffuse the projected image through rear projection a sheet of tracing paper will be used.
Computer Subsystem A personal computer with 20 GB free hard disk space, 1GB RAM and PIV + processor can be efficient enough. The Windows Vista operating system was chosen because the CCV package is highly supported in Windows.
Programming for the MT CCV is an open source C++ software package that contains code to analyze data from a camera, detect IR blobs from within the data, interpret that IR blob data, and generate TUIO events for the application to interpret. Since most operating systems only expect one mouse click at any single time, a new event and protocol must be used to interpret any number of touches, the TUIO protocol.
CCV: Hardware–Software Interface CCV acts as a driver for the multi-touch table device so that the computer embedded inside can interpret touches from the user or users. Individual applications can be written to interpret the data supplied from CCV and provide feedback to the display for the user or users.
CCV Calibration The CCV library comes with an interface to calibrate and test the blob detection for a multi-touch setup. Also, CCV comes with software to calibrate and test the camera that will be used with the multi-touch table.
Application Development Many different platforms can be used to develop multi-touch applications utilizing TUIO events. Such platforms include: Adobe Flash Java C++ Python Our demo application has been developed with ADOBE FLASH and is an open source s/w.
BUILDING MINI MT Cardboard box Cellophane sheet Camera Knife/cello-tape/A-4 sheets
APPLICATIONS OF MT Personal Computing Graphics Audio Mixing Video Playing Computer Gaming Slide Presentations……and many more!
That’s All….Thank you… For any assistance in building your own setup or for any other help feel free to contact: www.facebook.com/princejerry06 www.facebook.com/technicabar www.twitter.com/princejerry06 www.twitter.com/technicabar firstname.lastname@example.org