A Comparative Evaluation of Three Skin Color Detection Approaches

Skin segmentation is a challenging task due to several influences such as unknown lighting conditions, skin colored background, and camera limitations. A lot of skin segmentation approaches were proposed in the past including adaptive (in the sense of updating the skin color online) and non-adaptive approaches. In this paper, we compare three skin segmentation approaches that are promising to work well for hand tracking, which is our main motivation for this work. Hand tracking can widely be used in VR/AR e.g. navigation and object manipulation. The first skin segmentation approach is a well-known non-adaptive approach. It is based on a simple, pre-computed skin color distribution. Methods two and three adaptively estimate the skin color in each frame utilizing clustering algorithms. The second approach uses a hierarchical clustering for a simultaneous image and color space segmentation, while the third approach is a pure color space clustering, but with a more sophisticated clustering approach. For evaluation, we compared the segmentation results of the approaches against a ground truth dataset. To obtain the ground truth dataset, we labeled about 500 images captured under various conditions.

Influence of Comfort on 3D Selection Task Performance in Immersive Desktop Setups

Immersive virtual environments (IVEs) have the potential to afford natural interaction in the three-dimensional (3D) space around a user. However, interaction performance in 3D mid-air is often reduced and depends on a variety of ergonomics factors, the user's endurance, muscular strength, as well as fitness. In particular, in contrast to traditional desktop-based setups, users often cannot rest their arms in a comfortable pose during the interaction. In this article we analyze the impact of comfort on 3D selection tasks in an immersive desktop setup. First, in a pre-study we identified how comfortable or uncomfortable specific interaction positions and poses are for users who are standing upright. Then, we investigated differences in 3D selection task performance when users interact with their hands in a comfortable or uncomfortable body pose, while sitting on a chair in front of a table while the VE was displayed on a headmounted display (HMD). We conducted a Fitts' Law experiment to evaluate selection performance in different poses. The results suggest that users achieve a significantly higher performance in a comfortable pose when they rest their elbow on the table.

Jacob van Ruisdaels Buiten-Ansichten

In den Buiten-Ansichten Jacob van Ruisdaels zeigt sich eine einmalige Verbindung von Architektur und Naturkonzept in der niederländischen Malerei des 17. Jahrhunderts. Die Darstellung von luxuriösen Landvillen wird in eine illusionistische Landschaft gesetzt, die in ihrem Wildnischarakter den realen barocken Garten negiert. Ruisdael spielt bewusst mit der assoziativen Wirkung von Buiten- und Garten-Architektur, die durch ihre Übertragung in die Wildnis ihrer Funktion enthoben werden. Gleichzeitig erhält die Landschaft durch ihre Gruppierung um die Architektur eine Aufwertung zum Garten. Die dabei entstehenden Parallelen zur Gartenkunst des 18. Jahrhunderts, machen Ruisdael zu einem visionären Künstler seiner Zeit.

Influence of Information and Instructions on Human Behavior in Tunnel Accidents: A Virtual Reality Study

Human behavior is a major factor modulating the consequences of road tunnel accidents. We investigated the effect of information and instruction on drivers' behavior as well as the usability of virtual environments to simulate such emergency situations. Tunnel safety knowledge of the general population was assessed using an online questionnaire, and tunnel safety behavior was investigated in a virtual reality experiment. Forty-four participants completed three drives through a virtual road tunnel and were confronted with a traffic jam, no event, and an accident blocking the road. Participants were randomly assigned to a control group (no intervention), an informed group who read a brochure containing safety information prior to the tunnel drives, or an informed and instructed group who read the same brochure and received additional instructions during the emergency situation. Informed participants showed better and quicker safety behavior than the control group. Self-reports of anxiety were assessed three times during each drive. Anxiety was elevated during and after the emergency situation. The findings demonstrate problematic safety behavior in the control group and that knowledge of safety information fosters adequate behavior in tunnel emergencies. Enhanced anxiety ratings during the emergency situation indicate external validity of the virtual environment.

Advanced luminance control and black offset correction for multi-projector display systems

In order to display a homogeneous image using multiple projectors, differences in the projected intensities must be compensated. In this paper, we present novel approaches to combine and extend existing techniques for edge blending and luminance harmonization to achieve a detailed luminance control. Furthermore, we apply techniques for improving the contrast ratio of multi-segmented displays also to the black offset correction. We also present a simple scheme to involve the displayed context in the correction process to dynamically improve the contrast in brighter images. In addition, we present a metric to evaluate the different methods and their influence on the visual quality.

Über landschaftliche Gartengestaltung

Von Ernst Graf Silva Tarouca

Das Arboretum der Botanischen Lehrkanzel der Hochschule für Bodenkultur in Wien

Von Dr. Karl Wilhelm

Die für den Norden tauglichen und untauglichen Gehölze

Von E. Wolf und W. Kesselring

Die Felsensträucher und ihre Verwendung

Von A. Purpus

Etwas über winterharte Rhododendren

Von v. Oheimb

Das Arboretum der Lehrkanzel für Botanik bei der k. k. Hochschule für Bodenkultur in Wien

Von Dr. Karl Wilhelm

Die für den Norden tauglichen und untauglichen Gehölze

Von E. Wolf und W. Kesselring

Die Felsensträucher und ihre Verwendung

Von A. Purpus

Brioni

Von Alwin Berger

Die Libanonzeder, ein Forstbaum für den Süden Österreichs

Von Walter Siehe