Gilles is a French artist and is considered an "autistic sauvant".
"Gilles Tréhin (born 1972) is a French artist, author, and creator of the imaginary city of "Urville". His book, also titled Urville, is based on his writings of the fictional city's history, geography, culture, and economy, and includes over 300 drawings of different districts of Urville, all done by Trehin."
"Savantism is a rare condition in which people with developmental disorders have one or more areas of expertise, ability, or brilliance that are in contrast with the individual's overall limitations."
Visit his site here and read an article about him here.