Parallel cities

In this paper we introduce the concept of Parallel Cities---live, 3D simulations of actual cities kept "true to life" using real-time information from their real-world counterparts. A key enabler of the concept is the ever-growing tide of SNS (e.g., Twitter) updates, that can be aggregated and analyzed to obtain a rough, but macroscopically accurate picture of the current state of a city. Metaphorically, Parallel Cities will allow users to instantly "open windows" to any place in the world, providing an attractive enhancement to existing online mapping services. The paper will offer a concise discussion of the technical details of the concept, centered around descriptions of a working prototype that targets the city of Tokyo, Japan.