Koh uses two-dimensional photography to create holographic, three-dimensional constructions. His photo sculpture has a transparent surface that reflects the images of the world, and yet reveals the emptiness of its interior space. The overlapping planes create an illusion of indefinable depth and varying imagery, depending on the viewing angle. Stairway-14 is a trapezoid-shaped work that uses photographic images of the interior of the San Francisco Museum of Modern Art for its façade . The photographs were captured over four intervals in 2010 and collaged to form a structure where different temporal scenes coexist.