## 1 Introduction  
This paper presents a research result for smart cities that converge Information and Communication Technology (ICT) with city infrastructures, the activities in a city, environmental, medical, social, residential, and governmental systems. It provides smart services for citizen care, infrastructure management, traffic management, ecological environment management, energy management, etc. There are definitions for smart cities in global use. The Europe Union defines that \"A smart city is a place where traditional networks and services are made more efficient with the use of digital and telecommunication technologies for the benefit of its inhabitants and business.\" [1]. The International Telecommunication Union (ITU) defines that \"A smart sustainable city is an innovative city that uses information and communication technologies and other means to improve quality of life, efficiency of urban operation and services, and competitiveness, while ensuring that it meets the needs of present and future generations with respect to economic, social, environmental as well as cultural aspects.\" [2]. The International Standard Organization (ISO) also has its definition for smart cities. In smart cities, there are many video cameras that continuously produce big video data to provide smart city services. In general, smart cities need to stream and process a huge amount of video data efficiently and fast, and by many times in real-time [3,4]. Cloud technology can successfully address this requirement. In particular, Hadoop open source solution [5] with Cloud can be a good solution because it provides a platform to manage data with a simple MapReduce programming model and store data in a Hadoop Distributed File System (HDFS) [6]. It has been observed that the smart cities continuously generate unstructured big data. MapReduce allows us to handle large unstructured data as well as semistructured data. They were previously difficult to process. This paper presents Cloud-based UTOPIA Smart Video Surveillance (USVS) for smart cities. The Cloud-based USVS system gathers video data with scalable video streaming to effectively and smoothly handle video data flow from numerous video cameras even when network bandwidth is limited and fast process them for object detection with MapReduce models. The USVS is for UTOPIA, which is a smart city paradigm that consists of three tiers: UTOPIA infrastructure tier, UTOPIA middleware platform (SOUL) Tier, and UTOPIA portal tier. Video cameras are deployed in the UTOPIA infrastructure tier. Video cameras in the UTOPIA infrastructure tier can be remotely controlled according to the stored scenarios in the UTOPIA middleware platform tier. The administrator and authorized end users can also remotely control the video cameras in the UTOPIA infrastructure tier through the UTOPIA portal tier. The UTOPIA middleware platform tier plays a central role in the operation of smart cities and plays a pivotal role for USVS. The UTOPIA middleware platform tier has various functions such as Cloud computing, grid computing, ontology based context-aware intelligent processing, stream reasoning, real-time processing, image processing, scalable big data (including video data) streaming, ubiquitous computing, location-based processing, etc., so that UTOPIA can provide a variety of converged intelligent services and enable dynamic serviced execution [3, 4]. It has layer architecture so that it can have advantages of layer architecture such as good reusability and maintenance of functionality, easiness to add more functions, easy modification, better environment for scalability and fault tolerance, and better environment to deal with security threats. It provides a user-transparent infrastructure that generates smart city services. It enables users to control remote devices in real-time. It provides a convenient and easy-to-use user interface and supports various kinds of ubiquitous user portals.