Urban Prairie is an intuitive and interactive motion recognitive installation that allows for the extension of green spaces by intelligent use of design and technology via 4th dimension(time + space) design. The project serves to inspire and provoke discussions and speculations about the concept of inside versus outside, here versus there and virtual versus realism. Using an array of optical sensors and arduino boards, urban prairie captures and comprehends the movements of passers-by. This digital data is then translated into kinetic responses via a series of servos; creating the phenomenon of a sea of grass swaying in the breeze. The motion of the 'real' grass is in turn measured by a specially designed software and translated to a field of virtual prairie on screens behind the 'real' grass. The combined result is an 'Urban Prairie' which passers-by can engage and interact with through their movements in space.