The Remote Rendering Pipeline

Managing Geometry and Bandwidth in Distributed Virtual Environments
Project duration: 1996-1999
Funding: Austrian Science Foundation under contract no. P-11392-MAT
Contact: Dieter Schmalstieg, Michael Gervautz


Improvement of network and rendering performance in distributed virtual environments


Users can meet in a simulated world for social exchange, collaboration (computer supported cooperative work) and recreation.


The geometric description of this world (geometry database) must be available on every participating computer to allow rapid image generation. Simple solutions (such as found in computer games) often involve off-line distribution of the database (e. g. on CD-ROM) or stall the image generation until download is complete. The central problem is that the network is simply too slow.


The remote rendering pipeline is a concept to improve the availability of large geometry databases. It combines new methods in geometric modeling, network protocols and 3-D image generation to build a virtual environment that allows a large number of users to share a virtual world without waiting for slow network transmission.


The Remote Rendering Pipeline
D. Schmalstieg. Dissertation, Vienna University of Technology, 1997.

A Network Architecture for Remote Rendering
G. Hesina, D. Schmalstieg. Proceedings of 2nd International Workshop on Distributed Interactive Simulation and Real Time Applications (DIS-RT'98), pp. 88-91, Montreal, Canada, July 19-20, 1998.

Research inspired by the idea of a "remote rendering pipeline" has focused on a variety of topics, in particular multi-resolution and procedural modeling as well as network optimization:

Technical background
Demand-driven geometry network protocol:
For a virtual environment running in a client-server network configuration, an application protocol was developed that delivers pieces of the geometry database to the client "just in time" for rendering.
Level of detail modeling for VRML :
Geometric objects are represented at multiple levels of detail. The coarser representations are less pretty, but can be rendered faster and require less storage space. A level of detail generator for the popular VRML geometry standard was developed.
Smooth Levels of Detail :
Smooth Levels of Details (SLOD) were developed to allow a near-continuous geometry representation
  • unlike traditional geometric models, that are only usable as a whole, every byte of the new data structure that is received over the network becomes immediately usable.
  • the algorithm also yields a 3:1 data compression that further speeds up the network transmission
  • Animated Smooth Levels of Detail :
    In a follow-up project, the Animated Smooth Levels of Detail (ASLOD) approach was extended to support hierarchical scene graphs as well as organically deformable models. The resulting Animated SLOD or ASLOD system can render polygon geometry in a view dependent fashion.
    Natural phenomena from procedural models
    Very realistic and pretty natural phenomena such as trees, plants, and mountains can be defined by computer programs rather than modeled by hand. Such programs are often 100 x smaller than the raw geometric model and can therefore be transmitted over the network extremely fast.
    Spatially Extended Anchor Mechanism :
    The Spatially Extended Anchor Mechanism (SEAM) is a new paradigm of connection complex assemblies of distinct virtual worlds. SEAMS resemble doors between worlds, and are a powerful tools for organizing large networked virtual universes. They can also be used as "magic lenses" for enhancing user interfaces.

    This page is maintained by Dieter Schmalstieg. It was last updated on June 7, 2000.
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