Digital artist David Cousens reveals how to develop a sci-fi art sketch in Adobe Photoshop using the airbrush and a few nifty tricks. Traffic lights are everywhere aren’t they? No matter where you go, or how deserted the place is, the ubiquitous evil devices make their presence known, and for David...

The original photo: I locate it on the bottom layer to use for some initial tracing, primarily to save time and get the perspective correct. Some people prefer not to trace. My feeling is - been there done that - so I have no problem saving a bit of time by using a simple tracing technique. In Photoshop...