Report 17:   The PCMDI Visualization and Computation system (VCS): A Workbench for Climate Data Display and Analysis

Williams, Dean N. and Robert L. Mobley
March 1994, 107 pp. 

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This software was developed by the Program for Climate Model Diagnosis and Intercomparison (PCMDI) at the Lawrence Livermore National Laboratory in Livermore, California. It was designed to provide some of the basic capabilities needed for validating, comparing, and diagnosing climate model behavior. It can be controlled either interactively, or from a script file, or control can alternate between these modes during a session. A script can be saved during an interactive session and merely replayed, or it can be edited and replayed. The state-of-the-system can be dumped as a script at any instant, and that script can be used later to restore that instant of the session.

A graphic display page is made up of one or more graphic pictures. Each picture is defined by a picture template, a graphic method, and data. These three elements are termed the "primary elements" in this application. The picture template defines where to display; the graphic method defines how to display; and the data defines what to display. Tables of attribute sets have been created for each of the primary elements, and the application provides the user with the capability for creating a picture by choosing entries from these tables. Once a picture is created, it can be manipulated by changing the choice of primary elements or by altering them. This application also includes tables of basic elements that describe text, lines, markers, fill areas, patterns, colormaps, and lists. These basic elements are used to assign some of the attributes to the primary elements. This fact allows a picture to be manipulated by choosing different basic elements or by directly altering these basic elements.

Attributes for data can describe variables existing in a file or variables to be computed as a function of previously selected variables. The dimensions of variables can be subselected, reversed, transposed, wrapped, and thinned by selecting either a stride of nodes or by randomly selectring individual nodes. Grid transformations are supported by allowing a different set of dimension vectors to be specified in the dimension descriptors. A display page can be output as either Adobe PostScript for hardcopy, or as a raster image for hardcopy or animation.

UCRL-MI-123395