3D art's sure come a long way since M.C. Escher. Back in the late 1970's I was amazed at Escher's optical illusions in his converting mathematical formulas into art. New techniques have enabled today's artists to create unbelievable realism. These pencil drawings are by an artist in Santiago, Chile named Fredo. By using cleverly placed shadows, highlights, creative lighting and 3D perspective lines, Fredo tricks the eye into believing that his drawings are actually 3D. The drawing above looks like a real hand, but it's not!
M.C. Escher's Hands Pencil Drawing - 1948