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University of Stuttgart

	Institute for Visualization and Interactive Systems

A Framework for Interactive Remote 3D Visualization

Introduction

We developed a framework that provides remote control to Open Inventor or Cosmo3D based visualization applications. A visualization server distributes a visualization session to Java based clients by transmitting compressed images from the server frame buffer. Visualization parameters and GUI events from the clients are applied to the server application by sending CORBA (Common Object Request Broker Architecture) requests. The framework provides transparent access to remote visualization capabilities and allows sharing of expensive resources. Additionally the framework opens new possibilities for collaborative work and distance education. A teleradiology system and an automotive development application make use of the proposed techniques.

Technique

We developed a framework for the remote visualization of large scientific data sets. It is able to use 3D acceleration hardware of
the server system and allows to use these features from any Internet-connected PC interactively. The general scenario used for the
framework consists of an high-end visualization server for rendering images and one or more clients to provide a user interface, display the rendered images, and control the visualization (see Figure). There are no special requirements for the
choice of the clients. Even a PDA with TCP/IP network connection and adequate display resolution would be sufficient.

On the server side an Open Inventor or Cosmo3D based visualization application is rendering either images on-screen into the frame buffer or off-screen into the pbuffer. Thereby two different scenarios can be derived: A master user controls the session on the server machine and uses the visualization application locally. Images rendered on-screen into the frame buffer are encoded and transferred to all clients using a socket connection. The second scenario uses a display-less server that runs the server job in the background and renders into the pbuffer. The pbuffer is a special protected graphics memory block which allows hardware accelerated off-screen rendering. Images are read from this buffer into main memory, encoded and transferred to the attached clients using a socket connection.

The Java client enables transparent remote access to the visualization capabilities of the high-end server from any window system supporting platform. The received image data is decoded, stored as a Java2D buffered image and drawn into the frame buffer. Mouse and keyboard events generated on the client are transported to the server machine using CORBA method calls. The server provides an Open Inventor or Cosmo3D interface for these events that passes the parameters to objects and functions that handle the events on the server side. Thereby, when using Open Inventor, a manipulator widget can be remotely picked and dragged. Application parameters are transferred to the server using a second CORBA event interface.

Applications

Medical Volume Visualization:
Our approach allows working groups to discuss medical volume data sets collaboratively. 3D texture supporting graphics

Automotive Development:
Another example where the presented technique is very useful is the visualization in the car development process. In cooperation with the BMW Group we developed a Cosmo3D / OpenGL Optimizer based application which is in productive use in the pre- and post-processing of crash-worthiness simulations.

References

[1] K. Engel, Ove Sommer, T.Ertl: A Framework for Interactive Hardware-Accelerated Remote 3D-Visualization, Data Visualization 2000, Springer Computer Science, Pages 67-177, 291