Ulrich Leiner

Touchless Interaction-Novel Chances and Challenges

Touchless or empty-handed gestural input has received considerable attention during the last years because of such benefits as removing the burden of physical contact with an interactive system and making the interaction pleasurable. What is often overlooked is that those special forms of touchless interaction which employ genuine gestures --- defined as movements that have a meaning --- are associated with the danger of suffering from the same drawbacks as command based interfaces do, which have been widely abandoned in favor of direct manipulation interfaces. Touchless direct manipulation, however, is about to reach maturity in certain application fields. In our paper we try to point out why and under which conditions this is going to happen, and how we are working to optimize the interfaces through user tests.

Comprehensive evaluation of latest 2D/3D monitors and comparison to a custom-built 3D mirror-based display in laparoscopic surgery

Though theoretically superior, 3D video systems did not yet achieve a breakthrough in laparoscopic surgery. Furthermore, visual alterations, such as eye strain, diplopia and blur have been associated with the use of stereoscopic systems. Advancements in display and endoscope technology motivated a re-evaluation of such findings. A randomized study on 48 test subjects was conducted to investigate whether surgeons can benefit from using most current 3D visualization systems. Three different 3D systems, a glasses-based 3D monitor, an autostereoscopic display and a mirror-based theoretically ideal 3D display were compared to a state-of-the-art 2D HD system. The test subjects split into a novice and an expert surgeon group, which high experience in laparoscopic procedures. Each of them had to conduct a well comparable laparoscopic suturing task. Multiple performance parameters like task completion time and the precision of stitching were measured and compared. Electromagnetic tracking provided information on the instruments path length, movement velocity and economy. The NASA task load index was used to assess the mental work load. Subjective ratings were added to assess usability, comfort and image quality of each display. Almost all performance parameters were superior for the 3D glasses-based display as compared to the 2D and the autostereoscopic one, but were often significantly exceeded by the mirror-based 3D display. Subjects performed the task at average 20% faster and with a higher precision. Work-load parameters did not show significant differences. Experienced and non-experienced laparoscopists profited equally from 3D. The 3D mirror system gave clear evidence for additional potential of 3D visualization systems with higher resolution and motion parallax presentation.