Subject: spheres

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A student asks:

When I move my sphere to the left or right and then move them up
(more than 3) or down (less than 3) past the viewpoint (4,3,3)
the sphere start looking like ovals. Is this normal?

Dr. Westall sez:

This is probably a normal case of what is called perspective
distortion.  It also happens on "real" cameras with wide angle
("fisheye") lenses.

You should be able to reduce the effect by moving the viewpoint
back away from the screen (or exaggerate it by moving the
viewpoint even closer to the screen)