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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Augmented Reality Interaction for Semiautomatic Volume Classification
(The Eurographics Association, 2005) Río, A. del; Fischer, J.; Köbele, M.; Bartz, D.; Straßer, W.; Erik Kjems and Roland Blach
In the visualization of 3D medical data, the appropriateness of the achieved result is highly dependent on the application. Therefore, an intuitive interaction with the user is of utter importance in order to determine the particular aim of the visualization. In this paper, we present a novel approach for the visualization of 3D medical data with volume rendering combined with AR-based user interaction. The utilization of augmented reality (AR), with the assistance of a set of simple tools, allows the direct manipulation in 3D of the rendered data. The proposed method takes into account regions of interest defined by the user and employs this information to automatically generate an adequate transfer function. Machine learning techniques are utilized for the automatic creation of transfer functions, which are to be used during the classification stage of the rendering pipeline. The validity of the proposed approach for medical applications is illustrated.
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.
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.
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.
Experience of a Hybrid Information Space between an Outdoor Field and an Immersive Virtual World
(The Eurographics Association, 2005) Ogi, T.; Fujise, T.; Erik Kjems and Roland Blach
This paper proposes the concept of the hybrid information space that integrates the information seamlessly between the real world and the virtual world, and the prototype system was developed in which the immersive virtual world was constructed from the photograph images that were taken in the outdoor field. In this system, the user can go and come between the real world and the virtual world by using his own cellular phone as an interface device. This system was applied to relive travel experiences.
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.
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.
Reducing Fragmentation in Telecollaboration by Using IPT Interfaces
(The Eurographics Association, 2005) Roberts, D.; Al-Liabi, M.; Wolff, R.; Otto, O.; Al-Khalifah, A.; Erik Kjems and Roland Blach
Telecommunication systems, such as AccessGrid, allow collaboration across a distributed team. However, these systems typically introduce fragmentation into the view of the shared environment. Many have found that IPT systems offer several important advantages above other display technologies in supporting distance working. This study focuses on fragmentation, which has previously been shown to induce problems in efficient object referencing within a shared virtual environment accessed through desktop displays. We have attempted to repeat the experiment while varying the display type. The results reinforce previous studies by showing a significant improvement in task performance when the entire team uses IPT displays. We further show that the improvement is unlikely to come in this case from more natural interaction or navigation and thus postulate that it arises from more efficient mutual orientation towards objects of interest, arising from a reduction in fragmentation.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Evaluation of Collaborative Construction in Mixed Reality
(The Eurographics Association, 2005) Boschker, Breght R.; Mulder, Jurriaan D.; Erik Kjems and Roland Blach
Collaborative virtual and augmented reality are an active area of research and many systems supporting collaboration have been presented. Just like there are many different systems for VR and AR, there are many different types of collaboration. In some cases, virtual reality is used to enhance an existing collaborative process. In other cases, it enables new types of collaboration that previously were not possible (e.g. distributed VR). Other systems support tasks that can be performed either individually as well as collaboratively. While these tasks may allow to be performed collaboratively, little has been said on what the benefit is in doing so. We present a user study of a collaborative construction task in a shared physical workspace virtual reality environment under various degrees of interaction in collaboration. Our results show that, for this type of task, a pair of subjects concurrently interacting can be significantly more effective, even though individual user performance decreases. Our results further show that there is no significant benefit in giving only verbal and non-verbal assistance over a single user performing the task.
Using a single Spatial light modulator for stereoscopic images of high color quality and resolution
(The Eurographics Association, 2005) Hopp, Armin; Erik Kjems and Roland Blach
Since stereoscopy is a fundamental part of an immersive display, stereoscopic imaging has been part of many research papers and patents in the past. There have been different approaches developed to generate and transport the two images to the human eye. In general we can say that image generation may be done by one or two units and image encoding is done either by frequency, time or orientation. For image generation Projectors of CRT, LCD, LCOS and DLP Type are well known. Since 3D has gained more public interest, in the past different approaches have been undertaken to simplify setups for stereoscopy. Often two projectors are used to generate stereoscopic images. But these need more maintenance than a single projector system. For a single projector, frame interleaved stereoscopic Image generation is well known for 3Chip DLP Systems using three spatial light modulators to generate the image. In this paper we describe a solution producing frame interleaved output using a single chip spatial light modulator or digital micro mirror device (DMD) allowing combining high resolution and coloring quality.
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.

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