The second issue is solved by a visual guidance on the 3D
object considering the relationship between the 3D object and
the input 2D gesture. Since 2D coordinate of the gesture is a
projection of 3D object onto the touch screen, the coordinate
changes dependent on the view direction, and thus, multiple
gestures could be assigned at the same position on the screen.
For solution, single gesture is selected by filtering the multiple
gestures using depth information and the angle between
view direction and the gesture direction. In addition, possible
gestures are superimposed onto the 3D object to efficiently
show the next possible gestures to the end users.