6. Conclusion

Animations help in adding an expressive flavor to multimedia presentations. Though creating new animations generally takes lots of effort, a database approach can be utilized for reusing models and motions to create new animations. Since animations are represented in different formats, we have proposed a XML (eXtensible Markup Language) based mediator for handling the multiple formats. The XML mediator can handle animation formats such as VRML, MPEG-4, SMIL, and Microsoft PowerPoint. Other animation formats can easily be incorporated, if needed. The XML based mediator approach is natural since most animation formats are based on a hierarchical structure called scene graphs. It also has the advantage that most databases (such as Oracle or Microsoft Access) support XML representations and manipulations. It should be noted here that the XML mediator based animation toolkit presented in this paper does not try to solve motion transition problems or resolve object collision problems. Similar to other animation tools, users have to manually tweak the animations for proper object interactions.

The current implementation of the animation toolkit using XML mediator supports reuse of models and motions among formats such as VRML, MPEG-4, and Microsoft PowerPoint. We are working on incorporating animations represented in SMIL format. We are also developing more efficient techniques for (semi-) automatic metadata generation. These techniques will also help in efficient resolution of query by examples on complex animation models and motion sequences. The XML mediator approach can be extended to handle other techniques for animation generation. For instance, JPEG/BMP/GIF/TIF images can be used as texture maps in VRML file and then used in the proposed XML-based animation toolkit. In a similar manner, MPEG-1 and MPEG-2 can be converted to MPEG-4 and used in our model.