Wave-optical phenomena, such as diffraction, significantly impact the visual appearance of surfaces. Despite their importance, wave-optical reflection models are rare and computationally expensive. Recently, we presented a real-time model that accounts for diffraction-induced color shifts and speckle. Given that diffraction phenomena are highly dependent on illumination and viewing directions, as well as stereoscopic vision, we developed a VR demo to evaluate the new model. This demo shows the substantial impact of diffraction on the appearance of rough surfaces, particularly in stereoscopic viewing.

Virtual Reality (VR) systems rely on established real-time rendering techniques to uphold a strict performance budget of a few milliseconds per frame. The utilized techniques are based on approximations that trade speed-up for the correctness of the generated depth cues. The visual impact of these trade-offs, however, remains largely unexplored in the context of VR. In this paper we focus specifically on the perception of distorted specular reflections. Our research goal is to quantify the impairment of common reflection approximations on the resulting visual quality in VR. To this end, a subjective quality assessment is conducted, where participants rate the visual difference and visual annoyance of multiple established reflection approximations in a side-by-side comparison to a raytraced reference solution. We introduce the first dataset of its kind, containing 9 specular reflection approximations evaluated for two object types and three material smoothness values. Our results show the quality benefits associated with currently used reflection methods, and we discuss the implications for rendering VR environments.

This paper presents an image-based rendering approach to accelerate rendering time of virtual scenes containing a large number of complex high poly count objects. Our approach replaces complex objects by impostors, light-weight image-based representations leveraging geometry and shading related processing costs. In contrast to their classical implementation, our impostors are specifically designed to work in Virtual-, Augmented- and Mixed Reality scenarios (XR for short), as they support stereoscopic rendering to provide correct depth perception. Motion parallax of typical head movements is compensated by using a ray marched parallax correction step. Our approach provides a dynamic run-time recreation of impostors as necessary for larger changes in view position. The dynamic run-time recreation is decoupled from the actual rendering process. Hence, its associated processing cost is therefore distributed over multiple frames. This avoids any unwanted frame drops or latency spikes even for impostors of objects with complex geometry and many polygons. In addition to the significant performance benefit, our impostors compare favorably against the original mesh representation, as geometric and textural temporal aliasing artifacts are heavily suppressed.

Stereoscopic rendering is a prominent feature of virtual reality applications to generate depth cues and to provide depth perception in the virtual world. However, straight-forward stereo rendering methods usually are expensive since they render the scene from two eye-points which in general doubles the frame times. This is particularly problematic since virtual reality sets high requirements for real-time capabilities and image resolution. Hence, this paper presents a hybrid rendering system that combines classic rasterization and real-time ray-tracing to accelerate stereoscopic rendering. The system reprojects the pre-rendered left half of the stereo image pair into the right perspective using a forward grid warping technique and identifies resulting reprojection errors, which are then efficiently resolved by adaptive real-time ray-tracing. A final analysis shows that the system achieves a significant performance gain, has a negligible quality impact, and is suitable even for higher rendering resolutions.

This paper investigates the effects of normal mapping on the perception of geometric depth between stereoscopic and non-stereoscopic views. Results show, that in a head-tracked environment, the addition of binocular disparity has no impact on the error rate in the detection of normal-mapped geometry. It does however significantly shorten the detection time.

We propose the tool IslandViz for exploring modular software systems in virtual reality. We use an island metaphor, which represents every module as a distinct island. The resulting island system is displayed in the confines of a virtual table, where users can explore the software visualization on multiple levels of granularity by performing navigational tasks. Our approach allows users to get a first overview about the complexity of an OSGi-based software system by interactively exploring its modules as well as the dependencies between them.

We present an approach for exploring OSGi-based software systems in virtual reality. We employ an island metaphor, which represents every module as a distinct island. The resulting island system is displayed in the confines of a virtual table, where users can explore the software visualization on multiple levels of granularity by performing intuitive navigational tasks. Our approach allows users to get a first overview about the complexity of an OSGi-based software system by interactively exploring its modules as well as the dependencies between them.

In Augmented Reality, interaction with the environment can be achieved with a number of different approaches. In current systems, the most common are hand and gesture inputs. However experimental applications also integrated smartphones as intuitive interaction devices and demonstrated great potential for different tasks. One particular task is constrained object manipulation, for which we conducted a user study. In it we compared standard gesture-based approaches with a touch-based interaction via smartphone. We found that a touch-based interface is significantly more efficient, although gestures are being subjectively more accepted. From these results we draw conclusions on how smartphones can be used to realize modern interfaces in AR.