"Anamorphosis" - the general definition as it pertains to art, from Wiki - "is a distorted projection or perspective requiring the viewer to use special devices or occupy a specific vantage point to reconstitute the image."
There is an incredibly talented artist from the UK by the name of Julian Beever who's been producing sidewalk art - using a chalk medium - for over a decade now. His anamorphic illusions are drawn in a special distortion to create an impression of three dimensions when seen from one particular viewpoint.
Here's one of his completed projects, commissioned by Aveeno ...
Beautiful, is it not? How does he work on his projects without smudging the chalk? Seems as tho it would be an impossible task!
Well, he uses this X-type apparatus - padded at the top - and kind of hippety hops very carefully in and around the work in progress while he adds a touch of color here and a fountain there, as you will discover in this 4:18 video. I'd be willing to bet you'll watch this more than once. Just a fascinating process!
One of the things he likes to do when a work is completed is pose next to it. Here, it appears as tho he is sticking his toes into the water ...
This site has over 50 (!) photographs of his creations, a couple of which show what they look like if not viewed from the proper angle. The photos are very small on the page, but a single click quickly enlarges each of them. Really interesting!
One wonders, of course, how long they would last if it rained! Well, obviously not very long, huh? Probably a little less time than an ice sculpture would last out in the desert.
Once again, I have my friend Beth to thank for apprising me of Julian Beever's work. Thank you, Beth!