Preface

The Viz Roll is used to build scientific visualization clusters with Rocks. Traditional Rocks-based compute clusters consist of a single Frontend machine and several back end Compute machines. However, a Rocks-based visualization cluster is composed of Tile machines instead of Compute machines. A Tile machine must have an nVidia graphics card and may drive one or two LCD monitors (or projectors). The major visualization-middleware components are DMX, Chromium and SAGE.

DMX is part of the XFree86 project and has origins in the Xinerama code used to create a single X11 root window that spans across two physical monitors. DMX extends this to create a single root window (desktop) that spans across a rectangular wall of monitors or projectors. Although DMX can display OpenGL applications, it is recommended that Chromium be used with DMX for all OpenGL code. This Roll supports the use of DMX with and without Chromium support. It also supports Chromium in stand-alone mode for use without DMX.

SAGE (Scalable Adaptive Graphics Environment) is developed by the Cavern Group at the Electronic Visualization Laboratory (EVL) at the Univeristy of Illinois Chicago (UIC). SAGE can display both OpenGL and raw pixel blasting applications at full speed on large-scale tile displays. Applications must be written specifically for the SAGE environment, unlike DMX and Chromium. However, applications such as the SAGE version of mplayer can play HD qualities movies over a 60 tile wall at full speed, which is not possible using DMX (or Chromium).