Virtual Vellum Collaborative Prototype
The collaborative prototype of Virtual Vellum allows multiple sites to interactively control Virtual Vellum such that each site can see the changes in real-time. This was successfully trialled during an AHRC-funded access grid session (PI: Professor David Shepherd, HRI, Sheffield) on the 6th December 2006.
As opposed to running a single instance of Virtual Vellum and transmitting the screen capture to all remote locations, an instance of Virtual Vellum is run at each site. Each instance of Virtual Vellum connects to a main Virtual Vellum server. The Virtual Vellum server maintains a description of what should be seen, which includes parameters for the currently selected image index, magnification level and offset, thus totalling only a few bytes. When a Virtual Vellum client connects to the Virtual Vellum server, this description is sent to the client which configures itself accordingly, i.e. loads up the correct image, sets the magnification level and pans the image to the correct location using the offset parameters. When a user performs an action on a Virtual Vellum client, their screen is immediately updated as if it was running in a standalone version, and simultaneously data is sent back to the Virtual Vellum server. The Virtual Vellum server updates its description in accordance with what the client software has just done. This might for example be to change the magnification level or image position (again, this only requires the transmission of a few bytes). When the server receives changes to its description of what is being seen, it distributes them to each of the client instances of Virtual Vellum, which update accordingly, thus every Virtual Vellum client sees the same view and every client can change this view in real-time.
Further information and downloads will appear shortly.