1. A method performed under control of a computing device, comprising: receiving from a raw database at least one set of facial expression data and at least one external factor including at least one of population density, weather conditions and event information, each of the at least one set of facial expression data being accompanied by time information and location information and being obtained from at least one image, the at least one image being captured by a camera installed at a fixed geographic area; clustering the geographic area to form at least one cluster corresponding to general mood information determined based at least in part on the at least one set of facial expression data obtained from the at least one image captured by the camera installed at the fixed geographic area; storing the at least one cluster and the at least one external factor in a map database corresponding to the geographic area; obtaining a correlation between the at least one cluster and the at least one external factor; and based on the obtained correlation, attaching information of how the general mood information changes according to the at least one external factor to the map database.