Enhanced illustration using Magic Lens filters

In computerized 2.5D illustration systems such as Adobe Illustrator or CorelDraw, users construct pictures by layering geometrical shapes and specifying graphical properties such as line width, fill color, and transparency. In these systems, the act of applying a graphical property is closely tied to the way the individual objects in the design are constructed. For example, filled regions must be explicitly constructed and closed. Line and fill properties must be applied to complete outlines or line segments. Transformations can only be applied to complete objects or groups of objects. The designer must always plan to create object boundaries to define the extent of any visual effect. Effects that appear to cross object boundaries require the introduction of extra shapes and boundaries into the picture. We describe the value of including spatially bounded visual filters, called Magic Lens filters, as integrated elements in graphical illustrations. Because the effect of a Magic Lens filter is visible only within the lens´ boundary, the extent of this effect can be manipulated independently of the boundaries of the objects seen through it. This adds a new design element to the standard illustration system paradigm, making many forms of illustration easier to create. Magic Lens filters were introduced in 1993 as components of see-through user interfaces (E.A. Bier et al., 1993)