An Apple patent (number 20110090244) for an electronic sighting compass has appeared at the US Patent & Trademark Office. The invention relates to a portable electronic device -- iPhones, no doubt, as well as, perhaps, iPod touches and iPads -- having a compass function and, more particularly, to a device wherein the compass function is integrated with a camera function to provide an electronic sighting compass.

Per the patent, a portable electronic device provides a compass bearing display juxtaposed with or superimposed on a camera viewfinder display. The device includes an image sensor and an electronic compass. When the device is held with the image sensor pointed in a generally horizontal direction, the displayed viewfinder image from the image sensor is combined with a graphic indicating a compass bearing corresponding to the imaging axis of the image sensor. The display may be presented as a linear scale to indicate off-axis headings as well. Achim Pantfoerder is the inventor.

Here's Apple's background and summary of the invention: "The magnetic compass has been an indispensable navigational tool for centuries. Advances in electronics have made possible a miniaturized electronic compass. Such an electronic compass may be incorporated into a portable electronic device that may be conveniently carried about. The device may be configured to include additional functionalities, such as those of a cellular phone handset, a personal digital assistant (PDA), a digital multimedia player, or a multi-function consumer electronic device combining some or all of the foregoing functions. Currently available portable electronic devices having a compass function may include a display with an electronic representation of a traditional compass rose.

"It is often desirable to determine a compass bearing to a distant object. For this purpose, a magnetic compass fitted with a sighting device, referred to as a sighting compass, may be used. A bearing to a distant object can be readily determined by aligning the sighting device with the object while noting the compass reading.

"Implementation of the present invention provides a device in which a compass bearing display is juxtaposed with or superimposed on a camera viewfinder display. A portable electronic device includes an image sensor and an electronic compass. When the device is held with the image sensor pointed in a generally horizontal direction, the displayed viewfinder image from the image sensor is combined with a graphic display indicating a compass bearing corresponding to the imaging axis of the image sensor. The display may be presented as a linear scale to indicate off-axis headings as well."

-- Dennis Sellers