The Display

Finding the display

With the Upoint remote being able to sense its own orientation in a fixed coordinate system (spanned by the direction of Gravity and Magnetic North), the only hurdle standing in the way of establishing where on the display the user is pointing is the (relative) position, size and orientation of that display. There are of course numerous ways of obtaining this information, but for the invention to be user-friendly it is paramount that any setup procedures are as simple as possible.

Quite generally, the displayed images constitute a 2-dimensional area in space. Using a tool that can only measure distance and orientation (such as the Upoint remote) it would take quite an elaborate procedure to establish the 3D characteristics of this area. For this reason, Upoint methods simplify the underlying mathematical problem by assuming that the display is not merely some arbitrary (flat) object in space, but that it is in fact a rectangle with vertical and horizontal sides and, in some cases, with a well-defined aspect ratio. Because of these assumptions, the setup procedure becomes quite simple and, depending on the equipment used, can be performed with a 2-click procedure, 3-click procedure or even automatically.

It should be noted that, in reality, the display is never an exact rectangle with horizontal and vertical sides. Moreover, while pointing, a user will in addition to changing the Upoint remote's orientation always also slightly change its position. All of these factors will generate discrepancies between the actual point-of-aim (i.e., the point where a laser-dot would appear if the laser was turned on) and the calculated point-of-aim (i.e., where the cursor appears). Fortunately, though, such small errors will not be apparent to the user, since the visual feedback of the cursor provides the feeling of laser-like control.

The human aim

To explain, consider an experiment in which the user is asked to aim a laser-pointer at a point on the wall without actually turning the laser on. If the laser is subsequently turned on, it turns out that, in most cases, the actual point-of-aim significantly differs from the point where the user thought (s)he was aiming. In fact, the 'illusion' of laser-like cursor control is not as much afforded by the user having perfect aim or not, but rather by the dynamic behavior of the cursor in relation to where the user 'feels' (s)he is pointing. Long story short: under most circumstances the calculation errors made by the Upoint algorithms will never be noticed by the user.