A background map remains stationary relative to a portable unit while the portable unit moves within a plane parallel to the screen of the portable unit. As the user moves the unit, images of the background map appear on the screen of the portable device. The user scans the stationary map presented on the screen of the portable unit. This has several benefits since now relative distances and angular displacements within the plane between objects that are outside of the range of the screen of the handheld unit can be immediately be located and placed into view on the screen of a portable unit. The handheld unit is like a Sliding Window which provides a view of this image of a stationary map lying in the background of the portable unit.