“The concept illustration ‘Speed Runners’ was a personal project, mainly geared towards helping me get quicker results with my concept work. At the time, I was involved in creating a series of illustrations based on science-fiction themes using a ZBrush to Photoshop pipeline. ‘Speed Runners’ was a direct result of that multi-platform experiment.”
http://www.3dtotal.com/team/Tutorials_3/makingof_speed_runners/speed_runners_01.php