A spatially multiplexed autostereoscopic display is arranged to provide landscape and portrait operation. Multiple optical windows may be provided by spatial and temporal multiplexing techniques. A fast response lens array pair is aligned with a fast response spatial light modulator, and synchronized to provide first and second sets of images with first and second respective directionalities to provide first and second sets of respective optical windows. The first and second sets of optical windows may each comprise two or more optical windows in each viewing lobe. The optical windows may be arranged with an inclination to the vertical of 25 degrees to 65 degrees. An observer tracking system may be arranged to direct left and right eye image data to the left and right eyes of an observer, respectively, for landscape and portrait orientations of the display.