We present the results of an elicitation study exploring gestures that novice users find intuitive for controlling a group of four Unmanned Aerial Vehicles (UAVs). Particularly, we focus on group commands for (1) spatial distribution of the operated UAVs, (2) selection of the required UAV(s), and (3) their formation control. To elicit user-defined gestures, we conducted interview sessions in which we animated the considered commands with a 3D simulator. We identified commonalities in users' behavior and then used them to create the final input vocabulary. By using the concept of mental models we achieved coherence among the vocabulary entries.

We investigate how the use of metaphors supports the intuitiveness of gesture input vocabularies for Unmanned Aerial Vehicle (UAV) navigation. We compare gesture sets constituting a single metaphor to gesture sets that are based on mixed metaphors in terms of their respective intuitiveness. To this end, we implemented a 3D simulator in order to check how well novice users steer a UAV without knowing the valid gestures, using only a hint on the underlying metaphor. We compared their task completion time (indirect assessment of intuitiveness) with the one achieved after studying a gesture set that consists of gestures from several metaphors. We analyzed users' feedback reflected in questionnaires (direct assessment of intuitiveness) to further compare single metaphor gesture sets with mixed metaphors gesture sets. The results of the study support our hypothesis that a metaphor-based approach is an expedient means for gesture-based UAV navigation.

Previous in-depth analyses of the cursor paths taken by young children when they point at screen targets have shown that the fine-tuning movements that are necessary to accurately position the cursor over a small target can be very troublesome. We present two mouse pointing experiments with four-year-olds; the first re-evaluates the effect of PointAssist, a technique designed to help children performing fine-tuning movements by tracking the cursor and manipulating the cursor control-display gain in problem situations. The results partially confirm previously reported results showing that PointAssist can improve children's pointing accuracy when pointing at small targets. The second experiment investigates the effect of various (constant) cursor control-display gains on children's pointing performance. The results suggest a preference for higher gains.

In peephole interaction a window to a virtual workspace is moved in space to reveal additional content. It is a promising interaction technique for mobile projector phones to display large workspaces which contain more information than can be appropriately displayed on a small smartphone screen. In this paper we describe a projector phone prototype that implements peephole pointing without instrumenting the environment or using any additional hardware besides a smartphone and a handheld projector. This device allows for the first time to perform peephole interaction in the wild. Moreover, we demonstrate some applications we have built to exploit and investigate the full potential of peephole interaction with projector phones.

Studies in economic psychology have repeatedly revealed that energy consumption behavior in the household could be optimized through the provision of frequent and immediate feedback. This aspect is still widely neglected by conventional metering equipment installed in most homes. Energy meters are generally placed at quite hidden locations and reading them only once a year or at best once a month for billing purposes remains the rule. Especially observation of variations or trends over longer periods of time is cumbersome and has to be done on the basis of handwritings or transferring manually read data to applications like spreadsheets. We introduce Perceivable Energy, a system that supports pervasive approaches to raise awareness of energy consumption. More innovative feedback mechanisms like, e.g., ambient displays are backed by a more conventional graphical user interface to provide detailed consumption data on demand. The system is designed to make integration and interconnections of new metering devices and visualizations simple and constitutes a good basis for further research on awareness of energy usage in our (future) living environments.

In this paper we show how a model centered analysis of the usage of the mouse click interaction action in graphical user interfaces can be used to create a new menu system. The analysis identifies a possible new usage of the click action in cascading pull-down menus which can make it easier for the user during menu navigation and selection. A new menu system which is easy to implement, the ""Jumping Menu"", is introduced. The new menu system warps the screen cursor to the right into open sub-menu levels when a mouse click is detected inside a parent item. The Jumping Menu was compared with standard pull-down menus and force enhanced menus in a user experiment. The results show that the Jumping Menu and a force enhanced menu can facilitate menu interaction and that they are promising alternatives to conventional menu systems. Based on the results, a prediction model for selection times in Jumping Menus is developed.

We present the WWW-based interactive C++ Course developed at the University of Vienna to support introductory programming lectures of the first year of our Wirtschaftsinformatik ("business informatics") curriculum.The paper focuses on some major design concepts of the course as well as on the lessons learned during the project, such as the 3-layer structure of the course, ergonomic issues, an integrated programming interface with multi-user support, and maintainability issues.All of these may apply also to similar projects for different programming languages.

The metrics suite for object-oriented design put forward by Chidamber and Kemerer (1994) is partly evaluated by applying principles of measurement theory. Using the object coupling measure (CBO) as an example, it is shown that failing to establish a sound empirical relation system can lead to deficiencies of software metrics. Similarly, for the object-oriented cohesion measure (LCOM) it is pointed out that the issue of empirically testing the representation condition must not be ignored, even if other validation principles are carefully obeyed. As a by-product, an alternative formulation for LCOM is proposed.

The success of an experiment of using C++ as a first programming language for students of a specific type of computer science is presented.