<html><head><title>Persistence Of Visionaries</title></head>
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<center><h3>Persistence Of Visionaries</h3></center>
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  The term <i>persistence of vision</i> refers to the fact than an image formed on the retina leaves an impression which lingers for about 1/10 of a second. This enables video playback/television pictures to appear to change smoothly from one image to the next. During the gap between pictures, the eye 'remembers' the previous image.
<p>
  This is all very well, and appeared to be just another of those useless facts I routinely clutter up my brain with (useful only as a retort to those who say that 10 fps animation is too slow - actually it is the optimum speed), until, to my surprise, I found it applied to a <i>raytracer</i>, the purpose of which is surely to produce beautiful stills, not 10 fps animation! 
<p>
  I have often heard Persistance of Vision acclaimed as a great name for a raytracer. I have just as often reflected on the stupidity of humanity. I have, again, just as often remembered that POV started life on the PC, so we can't really expect the people who produced it to be completely human anyway.
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