Realtime Visualization of Large Images on a Thinwire

Problem Statement

We address the following issue: many visualization applications involve very large or complex images. Many visualization servers on the internet pre-select a set of subimages of this complex image for the visualizer. These subimages are of limited resolution and size (say 640x480) because of thinwire limitations. The pre-selected images are unlikely to be optimal for any particular user. Notice that the bandwidth usage in such servers highly asymetrical: practically all the bandwidth is from server to the user. An improved approach is taken by map servers: users can now zoom and pan over the entire image. But current map servers suffer from three problems:
1. visual discontinuities in zooming and panning (usually a brand new image is served up for each zoom/pan request)
2. smallness of viewing window (typically about 3"x4.5")
3. distinctly non-realtime responses
It may at first appear impossible to remove any of these problems within current bandwidth limitations. But we will show how we can ``effectively'' solve them using foveation methods.

Active Visualization Servers

As with current servers, we give the user the ability to continuously zoom and pan over the image. The received images are foveated, and the user can dynamically vary the foveation radius as well as resolution. It might appear counter-intuitive that such capabilities is desirable in a thinwire setting! But the key observation is this: we are, in effect, drastically reducing the server-to-client bandwidth in exchange for a modest increase in the client-to-server bandwidth.

Map Server Project

We are currently constructing an ``active map server''. One advantage of this particular application is that the issue of color maps does not incur a significant performance hit. Please click for information about our demo.
The above issue of pre-selecting subimages shows up in map servers as follows. One typically partitions the original large map into pages (and do this for each level of preselected resolution). The user experiences visual discontinuities when focusing at an area at the boundary between two pages.
Please go to publications for a paper describing this project.

RELATED LINKS

• Maps On Us from Lucent Technologies.
• MapQuest
• Progressive Transmission of Digital Images
  -- a project of Jeffrey Percival at the Space Astronomy Lab, U. Wisconsin.