By introducing the big screen positioning method based on visual touch
the visual touch principle is expounded and large screen touch system is built. In order to meet the requirements of accurate positioning
the full screen diagonal segmented calibration method is proposed and calibration points are fitted
the positioning for optical multi-touch system is achieved. The experiments demonstrated that in conditions of touching calibration points accurately
the vision-based big screen touch system is able to achieve accurate positioning within 3 pixels when the area is 2 cm away from the up edge of the screen. Positioning can be reached within 10 pixels when the area is within 2 cm from the up edge of the screen.