(a) The human visual hemifield corresponds approximately to a quarter sphere. The upper vertical meridian, lower vertical meridian, and horizontal meridian converge at the center of gaze. On a globe, the center of gaze and field periphery are equivalent to the North Pole and equator, respectively. (b) Inouye’s 1909 Mercator-style map of the primary visual cortex (color scheme added), with vertical lines representing parallels and horizontal lines representing meridians. The center of gaze at the occipital pole is transformed into a vertical line labeled 0°. The horizontal meridian runs from the center of gaze along the base of the calcarine fissure to the periphery. A narrow strip (−5° to 0°) is allocated to the ipsilateral central visual field. (c) Mercator-style projection for comparison with Inouye’s map, showing how latitudes become progressively enlarged nearer the North Pole (Snyder 1993, p. 182).