Assisting Target Acquisition in Perspective Views

• Du Yangzhou
• Chapuis Olivier
• Guiard Yves
• Beaudouin-Lafon Michel

This article introduces an interaction technique designed to assist target acquisition in flat documents that are visualized in perspective. One reason to allow camera tilts in graphical interfaces is that perspective views provide users with a gradual variation of scale, allowing them to see local detail in the context of a general overview. Our analysis, however, shows that the non-linearity of scale variation in a perspective view jeopardizes the acquisition of very remotely located objects. We introduce and experimentally evaluate a solution in which: 1. viewing angle is automatically coupled with tilt angle; and 2. the tilt is constrained so that the virtual camera stays at a constant altitude and remains pointed to a fixed spot on the document. Our results show that with our enhanced perspective navigation technique targets are easy to reach even for extremely high levels of difficulty. Target acquisition time obeys Fitts' Law and performance becomes as rapid as with the familiar pan and zoom technique.