Lattices in Perspective
This Demonstration shows a perspective rendering of disks or spheres in a cubic lattice. In order to view the rendering correctly, the eye should be directly above the center of the image, exactly one half of the width of the window away from the screen. Interestingly, the image with circles really is a perspective image of disks in space; when viewed from the correct vantage point, these are squashed into ellipses. On the other hand, spheres are drawn as elongated ellipses that appear to be perfectly circular when viewed correctly.