IPT/EGVE 2005: 9th International Workshop on Immersive Projection Technology, 11th Eurographics Workshop on Virtual Enviroments

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https://diglib.eg.org/handle/10.2312/372

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Running Large VR Applications on a PC Cluster: the FlowVR Experience
(The Eurographics Association, 2005) Allard, Jérémie; Ménier, Clément; Boyer, Edmond; Raffin, Bruno; Erik Kjems and Roland Blach
In this paper, we present how FlowVR enables the development of modular and high performance VR applications running on a PC cluster. FlowVR is a middleware we specifically developed targeting distributed interactive applications. The goal of the FlowVR design is to favor the application modularity in an attempt to alleviate software engineering issues while taking advantage of this modularity to enable efficient executions on PC clusters. FlowVR relies on an extended data flow model that enables to implement complex message handling functions like collective communications, or bounding box based routing. After a short presentation of FlowVR, we describe a representative application that takes benefit of FlowVR to reach a real time performance running on a PC Cluster.
Dynamic Bounding Volume Hierarchies for Occlusion Culling
(The Eurographics Association, 2005) Kovalcík, Vít; Tobola, Petr; Erik Kjems and Roland Blach
We present an algorithm for rendering complex scenes using occlusion queries to resolve visibility. To organize objects in the scene, the algorithm uses a ternary tree which is dynamically modified according to the current view and positions of the objects in the scene. Aside from using heuristic techniques to estimate unnecessary queries, the algorithm uses several new features to estimate the set of visible objects more precisely while still retaining the conservativeness. The algorithm is suitable for both static and dynamic scenes with huge number of moving objects.
Imperceptible Projection Blanking for Reliable Segmentation within Mixed Reality Applications
(The Eurographics Association, 2005) Kuechler, M.; Kunz, A.; Erik Kjems and Roland Blach
Applications that run in a projection-based mixed reality environment frequently require simultaneous image acquisition of the user by a camera. For later processing, very often a segmentation of the user s image is required, but along with the user, the camera captures the projected dynamic image in the background of the scene. This dynamic background complicates the later segmentation of the user in real-time. To ease segmentation, we introduce methods allowing to imperceptible blank the projected image for the camera. Four different methods are tested and compared. Acquired video streams are recorded and a successful segmentation of a user in front of a dynamic background is demonstrated. The paper concludes with an outlook on possible applications.
Modeling of Trees with 3D Gestures and Growth Simulation
(The Eurographics Association, 2005) Murakami, N.; Onishi, K.; Kitamura, Y.; Kishino, F.; Erik Kjems and Roland Blach
We propose a modeling system that enables users to create tree models with 3D gesture input. It generates tree models by using growth simulation based on the trunk or silhouette shapes of trees given by user gestures. The system carefully addresses the fragile balance and tradeoff between the freedom of user interaction and the autonomy of tree growth. Users intuitively and easily create tree models that have the exact features of branching structures or the silhouette shape of trees according to user intentions and imagination.
Towards a general concept for distributed visualisation of simulations in Virtual Reality environments
(The Eurographics Association, 2005) J.Metze,; Neidhold, B.; Wacker, M.; Erik Kjems and Roland Blach
We present a concept for Virtual Reality-Systems that allows easy design and implementation of applications in virtual environments as well as fast integration of new hardware and software components into an existing system of this type. Starting from an abstract module based approach for distributed systems we provide a guidance for specifying and designing components for VR-Applications with focus on the communication, administration and visualisation. Finally we have implemented a proof-of-concept for a cab simulator to demonstrate the effectiveness of our approach.
Enhanced Hand Manipulation for Efficient and Precise Positioning and Release
(The Eurographics Association, 2005) Osawa, N.; Erik Kjems and Roland Blach
Direct manipulation by hand is important in that it allows users to manipulate 3D virtual objects easily in an immersive virtual reality environment. Although direct hand manipulation is easy to understand and easy to use for approximate positioning, it has been considered unsuitable for making precise adjustments to virtual objects in an immersive environment because it is difficult to hold an unsupported hand in midair and then release an object at a fixed point. This paper therefore proposes automatic methods of adjustment to position and release virtual objects precisely. These methods are position adjustment, virtual hand size adjustment, viewpoint adjustment, and release adjustment. Combinations of these adjustments enable users to accurately manipulate virtual objects. Experimental evaluation revealed that release adjustment significantly increased the completion ratio for tasks and subjective preference for small targets.
Applications of Augmented Reality for Maintenance Training
(The Eurographics Association, 2005) Weng, Dongdong; Wang, Yongtian; Liu, Yue; Erik Kjems and Roland Blach
An Augmented Reality system that is designed for maintenance training is introduced. The proposed system adopts a projector to display the augmented video of the components to be repaired. With the augmented video, students can observe not only the real video of the components to be repaired, but also the additional information about the components such as contour, name and inner structure of the key parts etc. In order to accurately track the spatial relationship between the camera and the repaired components, several markers (small infrared LED) are attached with the components to be repaired, which ensure the dependability of the proposed system.
Näprä - Affordable Fingertip Tracking with Ultrasound
(The Eurographics Association, 2005) Reunanen, M.; Palovuori, K.; Ilmonen, T.; Mäkelä, W.; Erik Kjems and Roland Blach
In this paper we present Näprä, a novel tracking device suitable for fine motor interaction. The motivation for building the device was the need to track users' fingertips in an immersive free-hand drawing environment. Such tracking offers significant benefits for fine-grained artwork. Out of the numerous tracking methods ultrasound was chosen because of its affordability and low computational requirements. The design and implementation of both the hardware and software are discussed in detail in their respective sections. The device was evaluated in practice by two user tests, the first involving ten professional artists and the latter seven ordinary users. The results obtained in the tests are presented to reader as well as some directions for future work.
IntenSelect: Using Dynamic Object Rating for Assisting 3D Object Selection
(The Eurographics Association, 2005) Haan, Gerwin de; Koutek, Michal; Post, Frits H.; Erik Kjems and Roland Blach
We present IntenSelect, a novel selection technique that dynamically assists the user in the selection of 3D objects in Virtual Environments. Ray-casting selection is commonly used, although it has limited accuracy and can be problematic in more difficult situations where the intended selection object is occluded or moving. Selection-byvolume techniques, which extend normal ray-casting, provide error tolerance to cope with the limited accuracy. However, these extensions generally are not usable in the more complex selection situations.We have devised a new selection-by-volume technique to create a more flexible selection technique which can be used in these situations. To achieve this, we use a new scoring function to calculate the score of objects, which fall within a user controlled, conic selection volume. By accumulating these scores for the objects, we obtain a dynamic, time-dependent, object ranking. The highest ranking object, or active object, is indicated by bending the otherwise straight selection ray towards it. As the selection ray is effectively snapped to the object, the user can now select the object more easily. Our user tests indicate that IntenSelect can improve the selection performance over ray-casting, especially in the more difficult cases of small objects. Furthermore, the introduced time-dependent object ranking proves especially useful when objects are moving, occluded and/or cluttered. Our simple scoring scheme can be easily extended for special purpose interaction such as widget or application specific interaction functionality, which creates new possibilities for complex interaction behavior.
Pseudo-Physical Interaction with a Virtual Car Interior in Immersive Environments
(The Eurographics Association, 2005) Moehring, Mathias; Froehlich, Bernd; Erik Kjems and Roland Blach
The use of Virtual Reality technology for the product engineering process in the automotive industry has a lot of potential in particular in the area of usability and reachability studies. We analyzed the manipulation of knobs, controls, flaps, mirrors and other components in a real car and classified them with respect to their constraints. Based on this classification, we developed a set of pseudo-physical direct interaction techniques, which closely approximate the real world behavior without employing a force-feedback device. Our approach uses a hierarchical grasp heuristic to decouple the interaction from the collision of the fingers with the virtual car components. This approach makes the interaction more robust while no haptic feedback is available. A pilot study of our implementation revealed that our direct manipulation techniques are a good step towards more realistic interaction with virtual car interiors.
Interacting with Molecular Structures: User Performance versus System Complexity
(The Eurographics Association, 2005) Liere, R. van; Martens, J.-B. O. S.; Kok, A. J. F.; Tienen, M. H. A. V. van; Erik Kjems and Roland Blach
Effective interaction in a virtual environment requires that the user can adequately judge the spatial relationships between the objects in a 3D scene. In order to accomplish adequate depth perception, existing virtual environments create useful perceptual cues through stereoscopy, motion parallax and (active or passive) haptic feedback. Specific hardware, such as high-end monitors with stereoscopic glasses, head-mounted tracking and mirrors are required to accomplish this. Many potential VR users however refuse to wear cumbersome devices and to adjust to an imposed work environment, especially for longer periods of time. It is therefore important to quantify the repercussions of dropping one or more of the above technologies. These repercussions are likely to depend on the application area, so that comparisons should be performed on tasks that are important and/or occur frequently in the application field of interest. In this paper, we report on a formal experiment in which the effects of different hardware components on the speed and accuracy of three-dimensional (3D) interaction tasks are established. The tasks that have been selected for the experiment are inspired by interactions and complexities, as they typically occur when exploring molecular structures. From the experimental data, we develop linear regression models to predict the speed and accuracy of the interaction tasks. Our findings show that hardware supported depth cues have a significant positive effect on task speed and accuracy, while software supported depth cues, such as shadows and perspective cues, have a negative effect on trial time. The task trial times are smaller in a simple fish-tank like desktop environment than in a more complex co-location enabled environment, sometimes at the cost of reduced accuracy.
Binaural Acoustics For CAVE-like Environments Without Headphones
(The Eurographics Association, 2005) Assenmacher, I.; Kuhlen, T.; Lentz, T.; Erik Kjems and Roland Blach
The human auditory system, in contrast to the human visual system, can perceive input from all directions and has no limited field of view. As such, it provides valuable cues for navigation and orientation in virtual environments. However, audio stimuli are not that common in today s Virtual Reality applications, and this might result from the lack of middleware or user acceptance due to the need for specialized or costly hardware. Surprisingly, the lack of headphone-less near body acoustics is widely accepted, and simple intensity panning approaches that enable plausible spatial audio are used. This paper describes a networked environment for sophisticated binaural synthesis-based audio rendering in visual VR applications for a freely moving listener in a CAVE-like environment without the use of headphones. It describes the binaural acoustics rendering technique and a dynamic crosstalk cancellation system for four loudspeakers. In addition to that, synchronization issues and network coupling together with performance measurements that proof the applicability of the system in interactive Virtual Environments are discussed.
A Game Engine-based Multi-Projection Virtual Environment with System-Level Synchronization
(The Eurographics Association, 2005) Hashimoto, Naoki; Ishida, Yoshihiko; Sato, Makoto; Erik Kjems and Roland Blach
In multi-projector displays, which surround users with high-resolution images, a PC-Cluster is often used for realistic and real-time image generation. However, developing applications that support parallel processing on the PC-Cluster is quite troublesome. It is also difficult to acquire sufficient rendering performance because of the limited bandwidth of the PC-Cluster. Therefore, we aim to achieve affordable and accessible software environments for the multi-projector displays. In this paper, we describe a self-distributing software environment for inheriting existent game engines which provide basic functions of realizing virtual environments. This environment achieves minimum data communication based on a master-slave model. The communication mechanism is automatically applied to target applications by intercepting APIs. Hence we can directly exploit high-capability of the existing game engines on the multi-projector displays.
Feature Tracking in VR for Cumulus Cloud Life-Cycle Studies
(The Eurographics Association, 2005) Griffith, E. J.; Post, F. H.; Koutek, M.; Heus, T.; Jonker, H. J. J.; Erik Kjems and Roland Blach
Feature tracking in large data sets is traditionally an off-line, batch processing operation while virtual reality typically focuses on highly interactive tasks and applications. This paper presents an approach that uses a combination of off-line preprocessing and interactive visualization in VR to simplify and speed up the identification of interesting features for further study. We couch the discussion in terms of our collaborative research on using virtual reality for cumulus cloud life-cycle studies, where selecting suitable clouds for study is simple for the skilled observer but difficult to formalize. The preprocessing involves identifying individual clouds within the data set through a 4D connected components algorithm, and then saving isosurface, bounding box, and volume information. This information is then interactively visualized in our VR Cloud Explorer with various tools and information displays to identify the most interesting clouds. In a small pilot study, reasonable performance, both in the preprocessing phase and the visualization phase, has been measured.
Colosseum3D Authoring framework for Virtual Environments
(The Eurographics Association, 2005) Backman, Anders; Erik Kjems and Roland Blach
This paper describes an authoring environment for real time 3D environments, Colosseum3D. The framework makes it possible to easily create rich virtual environments with rigid-body dynamics, advanced rendering using OpenGL Shaders, 3D sound and human avatars. The creative process of building complex simulators is supported by allowing several authoring paths such as a low level C++ API, an expressive high level file format and a scripting layer.
Low-Cost, Portable, Multi-Wall Virtual Reality
(The Eurographics Association, 2005) Miller, Samuel A.; Misch, Noah J.; Dalton, Aaron J.; Erik Kjems and Roland Blach
Virtual reality systems make compelling outreach displays, but some systems highly suitable for outreach, notably the CAVE, have design features that make using them for that purpose inconvenient. In the case of the CAVE, the equipment is difficult to disassemble, transport, and reassemble, and typically only large-budget research facilities can afford such a system. We implemented a system like the CAVE that costs less than $30,000, weighs about 500 pounds, and fits into a fifteen-passenger van. A team of six people have unpacked, assembled, and calibrated the system in less than two hours. This cost reduction versus similar virtual reality systems stems from the unique approach we took to stereoscopic projection. We used an assembly of optical chopper wheels and commodity LCD projectors to create true active stereo at less than a fifth of the cost of comparable active stereo technologies. The screen and frame design also harbor portability optimizations; the frame assembles in minutes with only two fasteners, and both pack into small bundles for easy and secure shipment.
Virtual Pockets in Virtual Reality
(The Eurographics Association, 2005) Ilmonen, Tommi; Reunanen, Markku; Erik Kjems and Roland Blach
This paper presents the use of the virtual pocket user interface metaphor in virtual environments (VEs). Virtual pockets act like real-world pockets ó the user can put tools into pockets and select them with simple gestures. The pockets are body-centric and they can be used while the user is focusing on some object in the VE. We present the behavior of our virtual pocket implementation and compare its performance with different variations. The user tests show that virtual pockets are a useful metaphor and that selection of the correct feedback method has a strong impact on how well the pockets work.
Language Learning in Virtual Environments: Bobo and Apples
(The Eurographics Association, 2005) Holmen, H.; Nielsen, F.; Erik Kjems and Roland Blach
Bobo and Apples is one of the prototype games within SAME4KIDS (Speech-based,Animated, Multilingual,Educational games for Kids, http://same4kids.sourceforge.net/ ), a multi-language and multi-purpose games project for young kids of age 3-5 years. The main goal of SAME4KIDS is to expose young learners to multi-module games in various available platforms. In the prototype of Bobo and Apples , the game is designed to teach multiple languages and simple math within a frame of virtual environment, using mainly visual images, animation and sound. In this paper we introduce the main design concept and architecture for the prototype, as well as the envisioned VR conversion of the game, based on the Animarium system.
Tangible 3D: Hand Gesture Interaction for Immersive 3D Modeling
(The Eurographics Association, 2005) Kim, Hyosun; Albuquerque, Georgia; Havemann, Sven; Fellner, Dieter W.; Erik Kjems and Roland Blach
Most of all interaction tasks relevant for a general three-dimensional virtual environment can be supported by 6DOF control and grab/select input. Obviously a very efficient method is direct manipulation with bare hands, like in real environment. This paper shows the possibility to perform non-trivial tasks using only a few well-known hand gestures, so that almost no training is necessary to interact with 3D-softwares. Using this gesture interaction we have built an immersive 3D modeling system with 3D model representation based on a mesh library, which is optimized not only for real-time rendering but also accommodates for changes of both vertex positions and mesh connectivity in real-time. For performing the gesture interaction, the user s hand is marked with just four fingertipthimbles made of inexpensive material as simple as white paper. Within our scenario, the recognized hand gestures are used to select, create, manipulate and deform the meshes in a spontaneous and intuitive way. All modeling tasks are performed wirelessly through a camera/vision tracking method for the head and hand interaction.
Attribute Correlations between Haptic and Auditory Modalities
(The Eurographics Association, 2005) Baird, Bridget; Izmirli, Özgür; Heacock, Bradford; Blevins, Donald; Erik Kjems and Roland Blach
Correlations between attributes in the haptic domain and those in the auditory will assist in multimodal applications. This paper looks at the auditory attributes of pitch and reverberation and the haptic attributes of vibration, size and viscosity and seeks to correlate changes in one of the modalities with changes in the other. A total of 4 pairs of experiments were performed. The results indicate significant correlations in 3 of the pairs: pitch/vibration, pitch/viscosity, reverberation/size. There was no significant correlation found between reverberation and viscosity. These results have significance for designers of multimodal interfaces in virtual environments.

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