Check out this article:
Anamorphic Art with István Orosz
"Anamorphosis is an art of distorted projection or perspective requiring the viewer to use special devices or occupy a specific vantage point to reconstitute the image. The art of Anamorphosis was invented in China and brought to Italy in the 16th century, about the time Renaissance artists like Leonardo da Vinci were mastering 3-D and discovering slant anamorphosis."
Basically it's way weird.