  Cities are inherently dynamic. Interesting patterns of behavior typically
manifest at several key areas of a city over multiple temporal resolutions.
Studying these patterns can greatly help a variety of experts ranging from city
planners and architects to human behavioral experts. Recent technological
innovations have enabled the collection of enormous amounts of data that can
help in these studies. However, techniques using these data sets typically
focus on understanding the data in the context of the city, thus failing to
capture the dynamic aspects of the city. The goal of this work is to instead
understand the city in the context of multiple urban data sets. To do so, we
define the concept of an "urban pulse" which captures the spatio-temporal
activity in a city across multiple temporal resolutions. The prominent pulses
in a city are obtained using the topology of the data sets, and are
characterized as a set of beats. The beats are then used to analyze and compare
different pulses. We also design a visual exploration framework that allows
users to explore the pulses within and across multiple cities under different
conditions. Finally, we present three case studies carried out by experts from
two different domains that demonstrate the utility of our framework.
