Abstract: In apparatus for displaying map information, at least two maps of the same terrain but of different scale from one another are provided on a movable platform so that a portion of one of the images can be selected and displayed through an optical lens projection system of fixed magnification onto a projection screen and displaying through the optical lens projection system a portion of the selected portion of the one of the map images on the projection screen to examine the display of the other map image in that detail permitted by the scale of the other of the map images at the fixed magnification.