Virtual context - relating media objects to their real world subjects

Virtual Reality (VR) is sometimes used to give the user an immersive, three-dimensional sense of a real-world setting. VR is also sometimes used for information visualization, taking advantage of the perceptual characteristics of VR to convey information. This paper presents the Dam Square Virtual Context, a Web-based VR that is a combination of both these uses. This VR presents mock-ups of both Dam Square in the city of Amsterdam and the city's largest museum, the Rijksmuseum. This VR conveys abstract information that includes the relationships between objects in the museum, such as paintings of Amsterdam cityscapes, and the corresponding objects in Dam Square itself, such as the buildings and neighborhoods shown in these paintings. It is thus a multimedia combining VR wireframes and bitmaps with still images and interface scripts. The principle behind this is that the user learns how to walk through the museum to view objects that together convey a unified view about Amsterdam, which the user can then later walk through

A Probabilistic Multimedia Retrieval Model and its Evaluation

We present a probabilistic model for the retrieval of multimodal documents. The model is based on Bayesian decision theory and combines models for text-based search with models for visual search. The textual model is based on the language modelling approach to text retrieval, and the visual information is modelled as a mixture of Gaussian densities. Both models have proved successful on various standard retrieval tasks. We evaluate the multimodal model on the search task of TREC′s video track. We found that the disclosure of video material based on visual information only is still too difficult. Even with purely visual information needs, text-based retrieval still outperforms visual approaches. The probabilistic model is useful for text, visual, and multimedia retrieval. Unfortunately, simplifying assumptions that reduce its computational complexity degrade retrieval effectiveness. Regarding the question whether the model can effectively combine information from different modalities, we conclude that whenever both modalities yield reasonable scores, a combined run outperforms the individual runs

ABSTRACT RAM: Array Processing over a Relational DBMS

CWI is a founding member of ERCIM, the European Research Consortium for Informatics and Mathematics. CWI's research has a theme-oriented structure and is grouped into four clusters. Listed below are the names of the clusters and in parentheses their acronyms

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and their applications. SMC is sponsored by the Netherlands Organization for Scientific Research (NWO). CWI is a member o