Preprocessing and Screen-Cursor Mapping for a Virtual TouchScreen on a Projected Area

Virtual Touch Screen, on a projected area, is a system in which the projection on any ordinary flat surface provides us a graphical work-field for controlling specific kind of operations without any sophisticated touch sensors. Moreover, an ordinary screen area can be transformed into virtual touch screen with the use of a webcam and a projector. The webcam can take the picture of an indicator which may be a human finger with LEDs on its tip and then the touch screen is simulated by locating the indicator’s tip position on the picture to the position on the projected screen by the use of a Projector. As per the indicator’s tip movement on the picture, the cursor then moves on the projection surface. When the on screen picture is captured by the camera, several distortions may occur in the shape of the projection area due to the primitiveness of the captured picture and the picture may be more or less indistinct. Also if some parts of the picture are out of frame or out of focus then also the quality of picture may be compromised. Therefore, this paper focuses on preparing a model which, I) preprocesses the frames captured by the webcam and II) perfectly maps the indicator to the actual screen cursor by using bilinear transformation. Simulation results’, using the above proposed model, verifies the suitability of choosing such preprocessing and screen-cursor mapping in this paper. Keywordsbilinear transformation, screen-cursor mapping, virtual touch screen, touch sensors, frame preprocessing, human computer interaction.