Porcupine Tree are a British progressive rock band formed in Hemel Hempstead, Hertfordshire, England. The most successful project by musician Steven Wilson, as evidenced by its growing popularity, Porcupine Tree is also one of the most original and creative groups of its generation. With their mix of early progressive rock, psychedelia, ambient and (more recently) metal as well, they have crafted a body of work quite impressive for its diversity, and the distinctive quality of the sound in their recordings. All this shouldn't come as that much of a surprise, given the fact that self-taught audio engineer and producer Wilson is very well famed for being a hard worker, and listens to many different genres of music for inspiration, as he once commented: "I like so many different types of things and they all go into the melting pot if you like that produces the music of Porcupine Tree."

Metanoia is a limited edition album by British progressive rock band Porcupine Tree, first released in December, 1998. It's mostly made up of experimental outakes from the Signify sessions.