Bharti Temkin

Development of a haptic virtual environment

Haptics is a technology that creates a sense of touch in a multi-modal media. The availability of force feedback, haptics, requires the formation of haptic virtual objects. To aid in the creation of the haptic objects we have developed G/sub 2/H, an interface between a commercial graphics and animation software package and the PHANToM haptic device. G/sub 2/H is a modifier type plug-in that can be applied to any virtual object (created or imported). Application of the modifier converts objects into haptic objects. The objects can then be immediately touched with the haptic device in a number of configurable view-ports provided by the graphics software. G/sub 2/H also allows the dynamic changing of haptic object properties, such as stiffness and static and dynamic friction A physical medical model is used to develop haptic virtual 3D objects on a PC/NT platform. A commercially available digitizer and the graphics package are used to create virtual 3D objects. The application of G/sub 2/H then converts these objects into haptic objects. The process makes it possible to develop complex and precise haptic virtual objects without writing code, thus allowing developers to work at a higher level than that offered by current labor-intensive techniques. For PC/NT based haptic virtual applications, this capability allows touchable objects, including volumetric objects, to be quickly created with a high degree of resolution.

Simulated learning environments in anatomy and surgery delivered via the next generation internet.

The Next Generation Internet (NGI) will provide high bandwidth, guaranteed Quality of Service, collaboration and security, features that are not available in todays Internet. Applications that take advantage of these features will need to build them into their pedagogic requirements. We present the Anatomy Workbench and the Surgery Workbench, two applications that require most of these features of the NGI. We used pedagogic need and NGI features to define a set of applications that would be difficult to operate on the current Internet, and that would require the features of the NGI. These applications require rich graphics and visualization, and extensive haptic interaction with biomechanical models that represent bony and soft tissue. We are in the process of implementing these applications, and some examples are presented here. An additional feature that we required was that the applications be scalable such that they could run on either on a low-end desktop device with minimal manipulation tools or on a fully outfitted high-end graphic computer with a realistic set of surgical tools. The Anatomy and Surgery Workbenches will be used to test the features of the NGI, and to show the importance of these new features for innovative educational applications.

Graphics-to-haptics: a tool for developing haptic virtual environments

Current haptic application development tools typically require considerable programming efforts in order to make an existing surface-based graphical virtual environment (G-VE) touchable. In this paper we describe a graphics-to-haptics (G/sub 2/H) tool that provides a framework for developing the largest possible haptic virtual environments (H-VE) for stable haptic applications. G/sub 2/H automatically converts a G-VE into a haptic application with no additional programming via a real-time visual software development process of 1) importing G-VEs, 2) setting haptic and visual properties for models, 3) selecting graphics and haptic rendering algorithms, 4) representing the haptic device position in the virtual space, 5) interfacing different haptic devices to the virtual environment, and 6) testing and modify the virtual environment to ensure real-time stability of the created haptic application. The tested H-VE can be used as the foundation for other applications such as surgical simulators [Acosta, E et al., (2004), (2002)].

Networked stereoscopic virtual environment system

Advanced collaborative display systems allow users to view a computing desktop environment in a platform- and location-independent fashion. For real-time considerations, these systems become computationally very challenging, especially when video streaming is included. The addition of stereoscopic video streaming is desirable in virtual environments (VE) created for the teaching of anatomy and surgery with real-time collaborative audio and video interactions at many locations. However, this stresses the real-time requirements to the point at which realistic video is difficult to assure. For such a system to work, it is imperative that timing data be collected, analyzed and understood. We describe an experimental system designed primarily for the collection of timing data that is required for robust collaborative medical training applications. The networked stereoscopic system uses a server-swappable multicast network protocol to stream real-time manipulations of 3D virtual body structures at the server site to all clients participating in the multicast session. The three visual modes have dynamic tuning parameters for adjusting the parallax and the focal point for the rendered scene, allowing users to define individual stereoscopic comfort zones. Optimizing the graphics module is critical in achieving the necessary rendering rates. Different techniques of utilizing various memory resources increased the number of polygons rendered per second by over seven million. Depending on the type of memory used, the number of polygons rendered per second varies from 2.25 to 9.12 million.