Digital Matte Painting is my professional specialization; I am the guy who creates virtual sets - invisible backgrounds, set extensions or even full establishing shots - for film and TV. Traditionally this involved painting over a glass, which was later optically composited with the original footage, but nowadays matte paintings are done digitally, on computers, using a wide number of digital techniques, such as photographic manipulation, 3d rendering and some digital painting.
Most of the artworks you see above are personal work, and that's because, due to the nature of security measures of film production, I'm currently not permitted to show my professional work from any of the film projects I'm currently involved with.