SAS/SPECTRAVIEW Software User's Guide

Animating an Image with a BY Variable

With a BY variable assigned, you can animate an image in the Volume window. The values of a BY variable define groups of observations, such as hour, month, or year. Specifying a BY variable lets you see how response values change according to some grouping, like over time.

For example, if the specified BY variable is the hour of the day and a point cloud is displayed showing the amount of sulphur in the air at various coordinate locations, the point cloud reflects the amount of sulphur for the locations at 9 o'clock, 10 o'clock, and so on.

To produce animation with a BY variable:

First, you must specify a BY variable when you load the data. For instructions, see Grouping Observations with a BY Variable.
Use a visualization technique to display an image, such as a cutting plane, a point cloud, or an isosurface.
To automatically move through the BY variable values, which animates the current image, select [Auto BY], which is located at the bottom right of the interface. The values for the BY variable appear at the left of the BY variable slider, changing as the software moves through the values. (To stop the animation, click the left mouse button.)
To manually move through the BY variable values, for example, to see the image at a specific value, drag the BY variable slider, which appears below the display windows, to the left of [Auto BY].

For example, using the EPA data set and specifying HOUR as the BY variable, the following isosurface shows high sulfate concentrations at hour 23.

Specified BY Variable

[IMAGE]

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