Context modeling combined with motion analysis for moving ship detection in port surveillance

Abstract

In port surveillance, video-based monitoring is a valuable supplement to a radar system by helping to detect smaller ships in the shadow of a larger ship and with the possibility to detect nonmetal ships. Therefore, automatic video-based ship detection is an important research area for security control in port regions. An approach that automatically detects moving ships in port surveillance videos with robustness for occlusions is presented. In our approach, important elements from the visual, spatial, and temporal features of the scene are used to create a model of the contextual information and perform a motion saliency analysis. We model the context of the scene by first segmenting the video frame and contextually labeling the segments, such as water, vegetation, etc. Then, based on the assumption that each object has its own motion, labeled segments are merged into individual semantic regions even when occlusions occur. The context is finally modeled to help locating the candidate ships by exploring semantic relations between ships and context, spatial adjacency and size constraints of different regions. Additionally, we assume that the ship moves with a significant speed compared to its surroundings. As a result, ships are detected by checking motion saliency for candidate ships according to the predefined criteria. We compare this approach with the conventional technique for object classification based on support vector machine. Experiments are carried out with real-life surveillance videos, where the obtained results outperform two recent algorithms and show the accuracy and robustness of the proposed ship detection approach. The inherent simplicity of our algorithmic subsystems enables real-time operation of our proposal in embedded video surveillance, such as port surveillance systems based on moving, nonstatic cameras.