ON VISUALIZATION OF COMPLEX IMAGE-BASED MARKUP

We present methods to visually stratify overlapping markup for improved visualization of complex XML-based annotations of digital images. The problem arises in our development of editorial tools for creating image-based electronic editions, where overlapping and dense annotations make traditional markup representations cluttered, infeasible, or both. We discuss various techniques and formulate a set of constraints for efficient visualization of such markup. On the abstract level, the problem translates into visualizing data for nested and intersecting sub-polylines in a straight-segment polygonal curve. Using methods from computational geometry, such as power diagrams, we provide a complete and efficient solution to the problem.