Abstract
People expresses various motifs and appreciates those works in everyday life. This paper discusses the mechanisms of their activities what we call "Public Arts." Everyday works of photographs and videos are non professional which are supported by high-tech tools and systems. However it is not easy that they express and appreciate their own works by those technologies. From the point of people's "wants of expressing" we have studied structures and mechanisms of emerging the expressions. Nest structure of works, Coupling structure of expressing activities, and Place of settings are mechanisms of expressing activity. Design Space, Semi-Design Space, and Emergent Space are problem spaces of Expression.
