  The advancement of various research sectors such as Internet of Things (IoT),
Machine Learning, Data Mining, Big Data, and Communication Technology has shed
some light in transforming an urban city integrating the aforementioned
techniques to a commonly known term - Smart City. With the emergence of smart
city, plethora of data sources have been made available for wide variety of
applications. The common technique for handling multiple data sources is data
fusion, where it improves data output quality or extracts knowledge from the
raw data. In order to cater evergrowing highly complicated applications,
studies in smart city have to utilize data from various sources and evaluate
their performance based on multiple aspects. To this end, we introduce a
multi-perspectives classification of the data fusion to evaluate the smart city
applications. Moreover, we applied the proposed multi-perspectives
classification to evaluate selected applications in each domain of the smart
city. We conclude the paper by discussing potential future direction and
challenges of data fusion integration.
