Multimodal Spatio-Temporal Theme Modeling for Landmark Analysis

Here, we discuss mining and summarizing landmarks´ general themes as well as the local and temporal themes. General themes occur extensively in various landmarks, and include accommodations and other standard features. The local theme implies a specific theme that exists only at a certain landmark, such as a unique physical characteristic. The temporal theme corresponds to the location-time-representative pattern, which relates only to a certain landmark during a certain period-such as fleet week at the Golden Gate Bridge or red maple leaves in Kiyomizu-dera. Local themes are useful in landmark analysis for their discriminative and representative attributes. However, the ability to discover landmark diversity at different moments makes temporal themes equally important in landmark studies. Time dependent diversity shows complete viewing angles over time and complements local themes in landmark understanding. Furthermore, it provides more comprehensive and structured information for landmark history browsing and tourist decision making. We propose a probabilistic topic model called Multimodal Spatio-Temporal Theme Modeling (mmSTTM). The model considers both textual and visual contexts to learn general, local, and temporal themes, which span a low-dimensional theme space. The model also assigns all textual and visual keywords to each theme, along with a probability for each; a keyword with high weight assignment is meaningful for the theme, while low-weighted keywords are considered noise.