Perspective

In the following we would like to give the user “a feel” for the position of his hand in the 3D space in order to suggest him follow a certain hand path.

So we did the following

• track hand by drawing circles - a circle is simpler and easier to notice than a rectangle (because it's continuous, doesn't have corners)
• draw circle only if it is at a certain distance from the previous circle - this way the screen isn't filled when the user is not moving his hand
• reduce the number of circles drawn - also in order not to fill the screen
• circle size depends on the Z coordinate, the closer the hand is to the camera, the larger the circle

The problem is that the dimension of the circles comparing with when the hand is near the body opposite to when it is stretched out towards the camera, is not noticeable. So a dynamic circle dimension needed to be developed.

This was realised by changing the circle dimension with a fixed size and increasing/decreasing the current circle size depending on the increase or decrease of the Z coordinate.

Another method to give a sense of perspective would be to improve the human model (now represented only by lines) and vary the size of the body parts getting closer to the camera (increasing Z coordinate).