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Many interface devices for virtual reality provide full immersion inside the virtual environment. This is appropriate for numerous applications that emphasize navigating through a virtual space. However, a large class of problems exists for which navigation is not the critical issue. Rather, these applications demand a fine-granularity visualization and interaction with virtual objects and scenes. This applies to a host of other applications typically performed on a desktop, table or workbench. Responsive Workbench technology offers a new way to develop virtual environments for this rather sizable class of applications. The Responsive Workbench operates by projecting a computer-generated, stereoscopic image off a mirror and through a table surface. Using stereoscopic shuttered glasses, users observe a 3D image displayed above the tabletop. By tracking the group leader's head and hand movements, the Responsive Workbench permits changing the view angle and interacting with the 3D scene. Other group members observe the scene as the group leader manipulates it, facilitating communication among observers. Typical methods for interacting with virtual objects on the workbench include speech recognition, gesture recognition and a simulated laser pointer (stylus). This article features Responsive Workbench applications from four institutions that have pioneered this technology. The four applications are: visualization, situational awareness, collaborative production modeling and planning, and a virtual windtunnel.

In this virtual environment, customized scientific visualization tools offer specialists new ways to work cooperatively, which opens the door to more comprehensive analysis and, perhaps, reduced costs. Implementing the Responsive Workbench required close attention to several important elements: its components, a typical setup, the user interface, feedback speed and real-time rendering. >

The paper describes the concept of the Responsive Workbench (RW). This virtual environment was designed to support end users working on desks, workbenches, and tables as physicians, architects and scientists with an adequate human-machine interface. We attempt to construct a task-driven interface for this class of users by working in an interdisciplinary team from the beginning. The system is explained and evaluated along three medical applications: medical education, a cardiological tutorial with a simulation system for ultrasonographic examinations of the heart and surgery planning. Virtual objects are located on a real “workbench”. The objects, displayed as computer generated stereoscopic images are projected onto the surface of a table. The participants operate within a non-immersive virtual environment. A “guide” uses the virtual environment while several observers can also watch events by using shutter glasses. Depending on the application, various input and output modules can be integrated, such as motion, gesture and speech recognition systems which characterize the general trend away from the classical multimedia desktop interface. The RW is compared with other common virtual reality systems as head mounted displays. First experiences of the collaborators are drawn and future enhancements are proposed.

Shaders offer a wide range of possibilities, but at the same time limit the flexibility of an application as combining shader components is difficult. We present a novel object model for writing shaders for modern graphics hardware. These objects are defined and instantiated within an application. They are then propagated to the different programmable pipeline stages using a well-defined concept of copy-construction. Objects can reference each other and thus offer a flexible way to configure the shading set-up at run-time. Our framework is built on top of the object model for the standard illumination situation of surfaces and light sources. We show that many modern shading models can be expressed in this framework in a uniform and integrated way. Both, the object model and the framework, make the reuse of components practical and allow object-oriented design to be applied to the development of shaders.

In this paper we present an approach for a full cycle product customization in Virtual Environments (VE). The main goal of our work is to develop an integrated immersive framework, which allows configuring products from a great number of parts. Our framework supports collaborative work of two users and operates both on desktop computers and in immersive environments. The framework is integrated into a manufacturing environment, thus making the immediate production of customized products possible. The integrated modules of the framework allow importing CAD files directly into VE, creation of new objects on the basis of constructive solid geometry principles, attaching virtual connectivity-describing attributes to parts, guided assembly of parts and comprehensive analysis of products. In order to identify the influence of immersion and collaboration on the performance in assembly and manipulation tasks in VE, we performed a quantitative assessment of user performance, which we also describe in the paper.

In this paper we present our experience in using optical tracking systems in Virtual Environment applications. First we briefly describe the tracking systems we used, and then we describe the application scenarios and present how we adapted the scenarios for the tracking systems. One of the tracking systems is markerless, that means that a user doesn't have to wear any specific devices to be tracked and can interact with an application with free hand movements. With our application we compare the performance of different tracking systems and demonstrate that it is possible to perform complex actions in an intuitive way with just small special knowledge of the system and without any specific devices. This is a step forward to a more natural human-computer interface.

This paper presents a collaborative pointing technique for colocated multi-user interaction in projection-based virtual environments. Our approach uses bent pick rays to allow users to collaboratively work together without locking objects. Moreover, a user can manipulate distant objects in immediate reach, using a Scaled- Grab technique. The main purpose of the bent pick ray is to provide continuous visual user feedback, keeping a user informed about the collaborative manipulation.

Virtual environments (VEs) such as the Responsive Workbench were designed to support interactive, complex applications. The possibility of direct manual interaction with virtual objects, using both hands in a natural, intuitive way is one of the great advantages of such configurations. The related work on interaction techniques for these environments is mainly concentrated on hand-oriented, spatial manipulation. With increasing complexity of applications, application control issues become more relevant, including the problem of tool selection. In this paper, we propose a new interaction technique, optimized for handling tool selection tasks comfortably, called the ToolFinger. The ToolFinger is a hand held 3D widget, resembling a pen, to which a set of tools is assigned in a way that selecting and applying a tool are no longer two separated tasks. The ToolFinger concept allows a fluent integration of tool selections and tool switches with the workflow of geometry editing. It benefits complex manipulation tasks in applications such as immersive geometric modelling, or interactive visualisation.

A sketching system for spline-based free-form surfaces on the Responsive Workbench is presented. We propose 3D tools for curve drawing and deformation techniques for curves and surfaces, adapted to the needs of designers. The user directly draws curves in the virtual environment, using a tracked stylus as an input device. A curve network can be formed, describing the skeleton of a virtual model. The non-dominant hand positions and orients the model while the dominant hand uses the editing tools. The curves and the resulting skinning surfaces can interactively be deformed.

A two-handed 3D styling system for free-form surfaces in a table-like Virtual Environment, the Responsive Workbench (RWB)TM, is described. Intuitive curve and surface deformation tools based on variational modeling and interaction techniques adapted to 3D VR modeling applications are proposed. The user draws curves (cubic B-splines) directly in the Virtual Environment using a stylus as an input device. The curves are connected automatically, such that a curve network develops. A combination of automatic and user-controlled topology extraction modules creates the connectivity information. The underlying surface model is based on B-spline surfaces, or, alternatively, uses multisided patches [20] bounded by closed loops of curve pieces.

Recently prop-based interfaces in combination with two-handed interaction techniques have become increasingly popular. Passive real-world props augment interaction through tactile feedback and often lead to more intuitive interaction. The Cubic Mouse is a new, 3D input device based on the prop idea. It consists of a cube-shaped box with three perpendicular rods passing through its center. We use a six-degrees-of-freedom (6-DOF) tracker embedded in the Cubic Mouse to track the device's position and orientation. The rods can be pushed and pulled, allowing the constrained input of three degrees of freedom. The 6-DOF Cubic Mouse, also allows rotation of the rods, which adds another three DOF. Altogether, we have a total of 12 analog degrees of freedom available with the Cubic Mouse, six DOF through the tracking and another six through the rods. In addition, the Cubic Mouse has application-programmable control buttons. We present a variety of interaction techniques developed around the Cubic Mouse, which we have implemented in various application prototypes. Our geo-scientific visualization system allows the exploration of data from the oil and gas industry in local and distributed virtual environments. With our automotive partners, we're developing a system for steering and visualizing crash simulations. Other application areas include medical visualization and terrain visualization.

The Responsive Workbench [8] is designed to support end users as scientists, engineers, physicians, and architects working on desks, workbenches, and tables with an adequate human-machine interface. Virtual objects are located on a real “workbench”. The objects, displayed as computer generated stereoscopic images are projected onto the surface of a table. The participants operate within a non-immersive virtual environment. A “guide” uses the virtual environment while several observers can watch events by using shutter glasses. Depending on the application, various input and output modules have been integrated, such as motion, gesture and voice recognition systems which characterize the general trend away from the classical multimedia desktop interface. The system is explained and evaluated in several applications: A virtual patient serves as an example for non-sequential medical training. The car industry benefits from areas like rapid prototyping for exterior design and interactive visualization and examination of flow field simulations (virtual windtunnel, mixing processes). Visualization and verification of experiments with mobile instrument deployment devices in outer space missions are another fascinating application. Architecture and landscape design are another discipline well suited for the workbench environment.

Aus dem Bereich der Computergraphik existieren vielzahlige Methoden, welche hochste Anforderungen an die zugrundeliegenden Resourcen stellen. Benotigt werden hierbei sowohl grose Speicher- und Rechenkapazitaten zur effizienten Handhabung und Bearbeitung der anfallenden Datenmengen als auch schnelle Graphikrechner zur Darstellung der generierten Resultate. Da heutige Rechnerarchitekturen bislang nicht beiden Anforderungen genugen, und eine erhebliche Kostendifferenz zwischen numerischen, speicherkapazitiven Hochstleistungsrechnern und speziellen Graphikrechnern besteht, ist man auf breitbandige Kommunikationskanale angewiesen, welche eine effiziente Kopplung verschiedener Systeme erlauben. In der folgenden Arbeit soll szenarisch die Visualisierung groser Datenmengen durch Vernetzung graphischer und numerischer Hochstleistungsrechner dargestellt werden. Die konkrete Anwendung besteht hierbei in der interaktiven Darstellung und Bearbeitung hochaufgeloster skalarer Volumendatensatze, welche durch spezielle Verfahren fur die graphische Darstellung aufbereitet werden mussen.