Abstract: The spatial understanding of chemical molecules is crucial for learning chemistry at school. With a good 3D understanding of molecules, chemical processes become obvious compared to a 2D representation in textbooks or just the molecular formula. With the increasing spread of computers, smartphones and tablets, the field of computer aided learning becomes more and more important. Common molecular viewers such as Jmol (Jmol, 2012) present chemical simulations as 3D renderings on a regular computer screen in combination with desktop-based user interfaces using a mouse and a keyboard to manipulate 3D molecules. Such interfaces may be cumbersome to use since users have to associate 2D mouse motion and key presses with 3D object motions. In this paper we investigate the hypothesis that the understanding of spatial structures of molecules is enhanced by Augmented-Reality-based 3D user interfaces with which students can directly manipulate the virtual 3D molecules by freely moving and rotating a 3D object in air with their hands. Our results show that a direct manipulation 3D user interface improves the 3D understanding in comparison to the traditional desktop-based user interface with mouse and keyboard. 1

The calibration of optical see-through head-mounted displays is an important fundament for correct object alignment in augmented reality. Any calibration process for OSTHMDs requires users to align 2D points in screen space with 3D points in the real world and to confirm each alignment. In this poster, we present the results of our empiric evaluation where we compared four confirmation methods: Keyboard, Hand-held, Voice, and Waiting. The Waiting method, designed to reduce head motion during confirmation, showed a significantly higher accuracy than all other methods. Averaging over a time frame for sampling user input before the time of confirmation improved the accuracy of all methods in addition. We conducted a further expert study proving that the results achieved with a video see-through head-mounted display showed valid for optical see-through head-mounted display calibration, too.

Systems using two-handed spatial manipulation techniques also require strategies to enable system control tasks. These strategies make it possible to interact with the system comfortably while controlling two hand-held objects simultaneously. The Augmented Chemical Reactions project makes intense use of such two-handed interaction tasks. Users control virtual molecules and subsets that are registered to physical markers and try to combine those by selecting and then confirming a specific bond. When a desired bond has been selected, the user needs a way to confirm that bond without letting an atom go out of position. We developed and investigated two separate methods of confirming a selected bond when both hands are already doing a two-handed symmetric interaction task. The first method is a waiting method and the second method is a back&forth motion gesture. We evaluated the two methods in a user study, showing that the first technique, holding still, outperforms the other technique.