Dynamic grouping technique for ink and audio notes

Abstract

In this paper, we describe a technique for dynamically grouping digital ink and audio to support user interaction in freeform note-taking systems. For ink, groups of strokes might correspond to words, lines, or paragraphs of handwritten text. For audio, groups might be a complete spoken phrase or a speaker turn in a conversation. Ink and audio grouping is important for editing operations such as deleting or moving chunks of ink and audio notes. The grouping technique is based on hierarchical agglomerative clustering. This clustering algorithm yields groups of ink or audio in a range of sizes, depending on the level in the hierarchy, and thus provides structure for simple interactive selection and rapid non-linear expansion of a selection. Ink and audio grouping is also important for marking portions of notes for subsequent browsing and retrieval. Integration of the ink and audio clusters provides a flexible way to browse the notes by selecting the ink cluster and playing the corresponding audio cluster.