I have always been fascinated with optical illusions and more specifically impossible figures that use geometric or isometric shapes. New York street artist Aakash Nihalani creates bold geometric paintings and installations that interact with their environments using various mediums. His outdoor works are usually created using tape in various colours to create patterns or designs which often use forced perspective. The images of the installations often include people interacting with the artwork to create the forced perspective or enhance the illusion. You can see more of his work on his blog.