Temporal navigation in hierarchically structured media

The process of creating large documents like a computer program, a book, or a movie can take several years. During this process the author may want to return to earlier versions of the document in order to compare different iterations or to undo an earlier change. Navigating in the evolution of a document is usually a tedious process because exiting tools typically consider the history of a document as a whole. The user's navigation goals, however, are focused around a specific change from only a part of the document. We compare the navigation of document versions to video navigation, where we see interfaces that enable users to find a specific frame based on an object's location in the video.Unfortunately, these interfaces restrict which frames are accessible to those frames where an object moves. It is also difficult to directly translate these interfaces to non-video media media because they require a static frame of reference which does not typically exist in other media types. We discuss extensions of these video navigation interfaces that lift some, but not all, of the restrictions. We then go on to propose an alternative approach based on a document's changing structure. Because such a structure changes slowly over time, we can base temporal navigation around this structure as a reference point. We discuss the principles of strcutrue in temporal navigation interfaces and propose an approach to visualize and interact with hierarchical structures over time. We introduce a system for source code history navigation based on the soruce code's hierarchical structure. Users perform navigation tasks twice as fast using structure aware interfaces compared to existing similar interfaces. They also strongly prefer our visualization when it comes to exploration tasks. Finally, we discuss how to extend this approach to other media types and non-hierarchical structures