Analysis of Fundamental Parameters on Zooming and Rotation Using Pinch Gestures

previous research has not adequately investigated fundamental parameters, namely range of operation and preference, for zooming and rotation using pinch gestures on a multipoint touchscreen. This study obtained these fundamental parameters and introduced an innovative methodology to measure a comfort pinch. Thirteen right-handed participants were recruited to perform experimental tasks on a 23-inch touchscreen. The data showed that the maximal and comfort pinch in zooming were around 600 and 375 in pixels (160 and 100 in millimeters) for both hands while the range of rotation was 148-degree clockwise and 115-degree counterclockwise using the dominant hand. This study also found that participants preferred a 42-degree clockwise inclination to initiate rotation. Using non-dominant hands decreased the range of rotation but not the span of the pinch. Rotating with thumb fixed also significantly reduced the range of rotation. These findings could be used for guidelines in bimanual pinch manipulation, designing virtual rotary knobs, and other practical gesture operations.