Visualization Directions, Priorities and Tools for the
Stanford Linear Accelerator Center
Joseph Perl
Presented to the Workshop on Interoperability of DOE Visualization Centers
Lawrence Berkeley National Laboratory, Berkeley, CA
March 30-April 1, 1998

Background Information

The Stanford Linear Accelerator Center (SLAC) is a national basic research laboratory, probing the structure of matter at the atomic scale with x rays and at much smaller scales with electron and positron beams. The laboratory is operated by Stanford University under a contract from the United States Department of Energy (DOE).

The combined staff is currently about 1300, 150 of whom are Ph.D. physicists. Typically 800 physicists from universities and laboratories around the world participate in the high energy physics program and 800 scientists from universities and industrial laboratories are active in the synchrotron radiation program.

As with other High Energy Physics institutions, SLACís major visualization needs fall into two categories: 1) Event Displays and 2) other forms of Plots.

Event Displays are graphical representations of the particle interactions that are recorded by HEP detectors. Such visualizations may be 3D wireframes, stereo views, 2D projections of 3D space, 2D summings of 3D data or various specialized non-linear projections. Event Display images usually represent a single event in time.

Other forms of plots may be Histograms (two and three dimensional), Scatter Plots, Lego Plots, etc. The may represent various kinds of data such as hardware performance information, time histories and physics analysis results. They often represent the statistical summation of many separate events in time.

Collaborations currently taking data, such as SLD, rely on X-Windows based visualization tools running from Unix and VMS hosts.

Newer Collaborations, such as BaBar, while continuing to use X-Windows tools for the very near term, have as their long term goals more distributed computing approaches such as Java clients connected to Unix, VMS or WNT servers via CORBA and RMI.

a. High level directions and priorities at your facility
Provide tools to enable our user community to understand their detectors and their data. Do so in a manner that supports all of our users whether they are at SLAC, at other institutions around the US, around the world, in their offices or in their homes.

Take into account the extremely heterogeneous computing environment of servers, workstations and desktop systems in use within our international collaborations.

Take into account the realities of networks used by our international collaborations.

A more detailed view of our priorities can be seen in the Requirements Document recently prepared for the BaBar collaborations new event display:
Requirements for a New BaBar Event Display by Joseph Perl, Serge Du, David N. Brown, Anne-Marie Lutz, January 1998.

b. Broad views on future research activities for the next two years. What are the priorities at your facility?

Priorities for the future are the same as were expressed above.

The changes are that we are moving to newer technologies to better address those priorities. For example, X-Windows based solutions are being phased out in favor of Java.

c. What barriers or obstacles do you face with meeting (a.) and (b.)
Concern remains as to whether the "runs anywhere" character of Java will be maintained by the good faith of all vendors involved. Failing that, we will continue to search for other client/server solutions that can deliver powerful graphics in a network efficient manner without the requirement of extensive customization to particular vendorsí desktops.

d. What visualization tools are important to your program today and in the near future? We would like to compile a list of the software you currently use on the web. If the software you are using is locally developed, please supply the html link.

 The following locally developed products are still in heavy use but will be phased out as the currently running large experiment, SLD, reaches its conclusion:

DSP: the SLD Event Display
The Unified Graphics System (Robert C. Beach, SLAC CGTM 203)
Handypak: a Histogram and Display Package (A. Boyarski, SLAC-234)

The following products will remain important to our program in the near future:
PAW: Physics Analysis Workstation
JAS: Java Analysis Studio
GraDisplay: Graphics for BaBar
OPACS: the "o" Packages Visualization Environment
WIRED: World-Wide Web Interactive Remote Event Display