Automated

Finding the display: automated setup

When the projector is integrated into the system and is also equipped with an orientation and a distance sensor the task of finding the display's position, size and orientation becomes a lot easier, and can even be done automatically or almost automatically (depending on whether or not the associated Upoint remote uses a laser- or an ultrasonic distance sensor - see below)

Involving the projector: the automated setup procedure

To explain, consider the fact that the display lies, in a horizontal sense, nearly perpendicular to the optical axis of the projector (if it did not, the so-called keystoning effect would result in a distorted instead of rectangular projection, which the user will want to correct for by changing the horizontal and/or vertical angle of the projector). Hence, if the orientation of the projector is measured (in the fixed coordinate system spanned by the Earth's Gravity and magnetic North), the orientation of the display is known. If an appropriate distance between projector and display is also measured either by a cheap ultrasonic sensor (measuring in effect the shortest distance) or a laser sensor (measuring the distance along a well-defined line) it is clear that knowledge of the projection beam's dimensions is enough to uniquely establish the size of the display. Of course, in addition to the add-ons to the projector, a regular Upoint remote also needs to be added to the system.

Automated setup: additional components needed

The observant reader will have noted that there are two versions of the Upoint remote featured on this website: one employing a laser distance sensor and the other using an ultrasonic distance sensor, and that for the latter the procedure of cursor grabbing involved intersecting the pointing line with a horizontal plane in which the remote was 'usually wielded'. Hence, in order to make this 'ultrasonic version' of the Upoint remote operate successfully in combination with the automated display finding procedure, we still need to find a value for the one unknown left: the relative height of the projector with respect to the horizontal plane in which the remote is usually held by a particular user. This parameter is quite easily found, however, by requiring the user to point the remote at the projector during the one-time setup procedure. At this time, the orientation of the pointing line and the distance between remote and projector is measured, from which the relative height of projector (and hence display) and remote is easily calculated. Ultrasonic sensors are very well suited for this purpose, in particular because transducers can be mounted both on the projector as well as the receiver.