A relativity controller is a scroll bar/window combination that provides a way to see data in relation to both the context of its wholeness and the salience of its contents. To accomplish this, the linear density or other appearance of the scroll bar (acting as a ruler or scale) varies with the density of the document salience (as indicated by different kinds of annotations or marks). It also provides a way to zoom between perspectives. This is usable on many different data types: including sound, video, graphics, calendars and word processors.