(A) mobile-crowd service for massively packed people to instantly coordinate collective expressive activities

Abstract

People gather at a place as a crowd to express their common objectives, thoughts, and feelings together. It is a basic desire and the basic right of people. As a way of crowd expression, we see a crowd performs a collective visualization showing massive symbols by raising colored boards. Each individual takes a small part of the visualization by becoming a single pixel at his/her location in the crowd. The composite of all the individuals' pixels completes the crowd's visual message.In this thesis, I envision an innovation using mobile computing technologies to empower such a crowd by enabling them simply to hold their phones up and create a massive collective visualization. I propose Card-stunt as a Service (CaaS), which allows a densely packed crowd to instantly visualize symbols using their mobile devices and a server-side service. The key technical challenge toward realizing an instant collective visualization is how to achieve instant, infrastructure-free, decimeter-level localization of individuals in a massively packed crowd while maintaining low latency. CaaS addresses these challenges via mobile visible-light angle-of-arrival (AoA) sensing and scalable constrained optimization. It reconstructs the relative locations of all individuals and dispatches individualized timed pixels to each smartphone so that they can do their part in the overall visualization. CaaS successfully reconstructs individuals' locations at a typical error of 15 cm in real deployment so that 49 participants can perform the high-quality collective visualization.With a fully working service, I uncovered novel crowd experiences of CaaS. To this end, I conducted live deployment studies with 60 participants. I present novel findings from the participants’ hands-on, empathetic feedback. I open up a new genre of mobile-crowd service and introduce a new research area to the social computing community by highlighting the importance of the crowd in physical spaces.