Moving Markup: Repositioning Freeform Annotations

Abstract

Freeform digital ink annotation allows readers to interact
with documents in an intuitive and familiar manner. Such
marks are easy to manage on static documents, and provide
a familiar annotation experience. In this paper, we describe
an implementation of a freeform annotation system that
accommodates dynamic document layout. The algorithm
preserves the correct position of annotations when
documents are viewed with different fonts or font sizes,
with different aspect ratios, or on different devices. We
explore a range of heuristics and algorithms required to
handle common types of annotation, and conclude with a
discussion of possible extensions to handle special kinds of
annotations and changes to documents.