Touch Shadow Interaction and Continuous Directional User Interface for Smartphone

We propose a new touch screen interaction named as Touch Shadow, which is based on the contact area and the resultant shape of the fingertip when it touches the touch surface. The results of our feasibility evaluation established three degrees of freedom for the Touch Shadow interaction based on three fundamental parameters, the touch surface area, displacement of the touch centroid and direction of the press. For this interaction, we designed several user interface options that can support continuous interaction. Based on the review feedback from 6 UI designers, we finally selected three of them, the Bubble Shadow, Rectangular Shadow and Beam Shadow for user evaluation. A proof of concept prototype was developed for Android smartphones and was tested with 10 users for maps application scenario. The participants rated the experience of using Touch Shadow with continuous direction UI on the map to be high.