UvA-DARE ( Digital Academic Repository ) The MediaMill TRECVID 2008 semantic video search engine

In this paper we describe our TRECVID 2008 video retrieval experiments. The MediaMill team participated in three tasks: concept detection, automatic search, and interactive search. Rather than continuing to increase the number of concept detectors available for retrieval, our TRECVID 2008 experiments focus on increasing the robustness of a small set of concept detectors. To that end our concept detection experiments emphasize in particular the role of sampling, the value of color invariant features, the influence of codebook construction, and the effectiveness of kernel-based learning parameters. A robust but limited set of concept detectors necessitates the need to rely on as many auxiliary information channels as possible for retrieval. Therefore, our automatic search experiments focus on predicting which information channel to trust given a certain topic, leading to a novel framework for predictive video retrieval. To improve the video retrieval results further, our interactive search experiments investigate the roles of visualizing preview results for a certain browse-dimension and active learning mechanisms that learn to solve complex search topics by analysis from user browsing behavior. The 2008 edition of the TRECVID benchmark has been the most successful MediaMill participation to date, resulting in the top ranking for both concept detection and interactive search, and a runnerup ranking for automatic retrieval. Again a lot has been learned during this year’s TRECVID campaign, we highlight the most important lessons at the end of this paper.