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5.4.2 Information Mural

The Information Mural presents Slides, Sections, and Topics in a symbolic view, which emphasizes temporal location and duration.

This visualization is present in Lecture Browser versions 0 and 1, but was removed from version 2 due to its lacking popularity during user studies.

In a sparse visual matrix, Topics are represented on the vertical axis, Slides and Sections are modeled on the horizontal axis. Each Slide assumes a narrow rectangle, colored by its media type. The number of Slides in a Section (indicative of the temporal duration) are proportionally modeled by the number of narrow rectangles, which grow into horizontal bars. Important Sections, i.e. those with many content Slides, readily stand out in this graphical view. With the progression of the lecture, this graph places new Topics below existing ones (the graph grows downwards), while maintaining the temporal context along the growing horizontal axis. Topics with several Sections are clearly indicated by their temporal breaks in the horizontal axis in the respective Topic.

Figure 1.14: Information Mural representing continuous topics
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This visualization provides quick graphical insight into the dynamic of a lecture: For a lecture, in which contents (Topics) are presented strictly going forward, i.e. without back-referencing, the Information Mural yields a diagonal line. However, if the instructor frequently references material from temporally disjunct parts of the lecture, the Information Mural develops a broken diagonal with off-diagonal content Slides.

Figure 1.15: Information Mural representing dis-continuous topics
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A color bar displays the media type for each Topic on the vertical axis. Clicking on a Topic's color rectangle selects the Slides for that Topic. A horizontal semi-transparent line marks the selected Topic. The Topic is also selected in the Lecture Browser's other visualization frames. The Slide Player can now be used to play back a slide show for the Topic.

Figure 1.16: Information Mural during Playback
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The Slide Player control panel was featured in the Information Mural in version 0 of the Lecture Browser. In versions 1 and 2, these controls were moved to the application's toolbar.

Slide Player controls from left to right include: Play in reverse, Play forward, Pause, Rewind, Skip to last slide, Next slide, Previous slide. The last two buttons can be used to speed up the slide show during playback. These two buttons can also be used to manually browse through the selected Slides while not in playback mode.

Figure 1.17: Playback controls