Applications in the e-Biolab

To let the twenty displays of the tiled display work as a single display special software is needed. For the this purpose SAGE is used. Under SAGE a number of applications are available for data analysis in the e-Biolab.

SAGE

The tiled-display runs SAGE. It is a graphics streaming architecture for supporting collaborative scientific visualization environments for very high display resolution. It is developed by the EVL. SAGE allows the streaming of multiple image streams to arbitrary locations on the tiled display under control of the user. SAGE comes with a number of applications for the display of various data streams. In addition, a number of applications were developed specifically for the e-Biolab.

Image data

SAGE comes with an imageviewer which is capable to show common image formats on the tiled display. This works well for relatively small (up to about 20 megapixel) images. Larger images take a long time to process as processing is done on a single machine in the display cluster.

For large images JuxtaView can be utilized. With JuxtaView very large (gigapixel+) images can be displayed and navigated (panning and zooming) on the display. The program is parallelized using mpi and therefore acceptable frame rates can be achieved even on very big images. To be able to use JuxtaView images must be translated to a format accepted by JuxtaView, distributed over the render nodes and possibly cut into pieces. JuxtaPush can be used to speed up the preparation of arbitrary images for display using JuxtaView.

For collections of images zap can be used. This program takes care of distribution of the image collection over the tiled display taking into account the windows already on the display and the mullions between screens. The program optimizes the amount of visible pixels for each image in the collection.

For the display of remote content a v-browser plugin is available. Using v-browser images in a SRB repository can be shown on the tiled display

Video streams

A port of VLC to SAGE can be used to display video streams such as movies or teleconferencing sessions on the tiled display.

Graphical interactive application output

To show the the output of an arbitrary applications on the tiled display an adapted version of a VNC-client which runs under SAGE is available. It can connect to any network-connected machine on which a vnc-server is running. The screen of that machine is echo-ed onto the tiled display with some delay, typically in the order of one or a few seconds.

Zap can be used to display snapshots of a arbitrary X-window on computers connected to the display cluster. The snapshots made during a session can be stored and put on the tiled display at a later moment.

Applications utilizing OpenGL for rendering for which the source is available can be relatively easily ported for use on the tiled display. Some code has to be added in order to read the frame buffer before the glSwapbuffers call. The read pixels are then sent to the tiled display.