SAS/SPECTRAVIEW Software User's Guide

Glossary

autoexec file	an external file containing SAS statements that are executed automatically when the SAS System is invoked. You can use the autoexec file to specify SAS system options, as well as librefs and filerefs.
axis	a one-dimensional line representing the zero point on a scale used to plot values of the x,y,z coordinates. The X axis represents width, the Y axis represents height, and the Z axis represents depth.
axis variables	the data set variables that you specify for the X axis, the Y axis, and the Z axis.
bounding box	a set of lines that outline the three-dimensional volume grid representing the data.
BY variable	an optional variable specification whose values define groups of observations, such as hour, month, or year. Specifying a BY variable allows you to animate an image so that you can see how response values change according to some grouping, like over time.
categorizing data	to group numeric data creating distinct ranges for each axis.
click	to press and quickly release a mouse button.
color palette	lets you customize colors for response value ranges, missing values, an isosurface, and image annotations.
continuous data	data containing few gaps that vary slightly over a large range, like weight and height.
coordinates	the values representing the location of a data point along the X, Y, Z axes.
cutting plane	a visualization technique that produces slices of data, either perpendicular to an axis or not perpendicular to any axis. In addition to the axis cutting planes, you can request two- and three-dimensional surface views (surfaces, charts, stacks, and plots) at a specific cutting plane's location.
data filtering	a data processing option that smooths or sharpens the data in order to deemphasize or highlight variations in response values. SAS/SPECTRAVIEW provides several predefined filters, or you can create your own.
data point	the location in three-dimensional space of an x,y,z coordinate.
data ramp	the column of data value ranges and associated colors on the color palette that you can use to customize response colors in images.
direct volume rendering	a visualization technique that creates a two-dimensional image of the entire volume of data points with transparency.
discrete data	data consisting of distinct values (non-continuous) containing natural gaps, like patient IDs and years.
display windows	the four interface windows that display the images for viewing and manipulation.
drag	to press and hold a mouse button while moving the mouse.
filler points	the data points generated by the software to fill the volume grid in locations not occupied by data points plotted from X, Y, and Z values.
grid	See volume grid.
interpolate	to estimate values between two or more known values.
isosurface	a visualization technique that produces a three-dimensional surface by connecting all the data points with one response value.
libref	an arbitrary name that you make up to symbolically represent a SAS library.
major tick marks	the points on an axis that mark the major divisions of the axis scale.
minor tick marks	the divisions of the axis scale that fall between major tick marks.
missing values	a value in the SAS System indicating that no data is stored for the variable in the current observation.
NOR plane	a cutting plane that is not perpendicular (non-orthogonal) to any axis.
observation	the horizontal component of a SAS data set. Each observation contains one data value for each variable in the data set. In SAS/SPECTRAVIEW software, an observation contains the x,y,z coordinates for a data point and the response value for that location.
opacity degree	the setting that determines the data points that are to be visible in an image produced by direct volume rendering.
point cloud	a visualization technique that displays response values with colored markers, showing individual data points.
probe analysis	a customization option that displays the response value for a specific data point in an image.
response histogram	a bar chart that displays both the frequency distribution of data points that share the same response value and the colors that represent those values. You use the histogram to specify a subset of response values for a point cloud and to specify the response value for an isosurface.
response values	the measured responses that are associated with each data point in the volume. The measured response could be, for example, density, porosity, or wind velocity.
response variable	the SAS data set variable whose values are measured responses that are associated with each data point in the volume.
RGB	a color-coding scheme that specifies a color in terms of percentages of red, green, and blue components.
SAS data set	the internal format used by the SAS System. A SAS data set contains descriptor information and its related data values organized as a table of observations (rows) and variables (columns) that can be processed by the SAS System.
solid-volume image	a visualization technique that produces a colored, three-dimensional, solid-block image of the data points, providing an overall view of the data at the volume's border.
sparse data	data that does not contain at least one value for an x,y,z coordinate within the volume grid, like random data.
splat width	the setting that determines how solid the rendered image is to be.
text window	a window in the interface where messages give you instructions, inform you of current conditions and errors, and so on. You also enter values and names in this window.
three-dimensional	having three dimensions, that is, width, height, and depth. A three-dimensional area can be defined by points having three coordinates relative to the X, Y, and Z axis.
TIFF file	a Tagged Image File Format, which is a format for scanned images.
two-dimensional	having height and width but not depth. A two-dimensional plane consists of points or lines defined by coordinates that are relative to two axes, for example, the X axis and the Y axis.
variable	a column in a SAS data set. Each SAS variable can have the following attributes: name, type (character or numeric), length, format, informat, and label.
volume grid	an invisible network of lines that intersect data points in three-dimensional space. The shape and size of the volume grid is determined by the number of distinct X, Y, and Z values.
volume visualization	the process of creating a three-dimensional image that represents data, providing both surface and interior views.
WHERE clause	allows you to specify a subset of data to be read into SAS/SPECTRAVIEW.
X axis	the axis that specifies width in the coordinate system. The first value in an x,y,z coordinate set represents a location in space relative to the X axis.
X variable	the SAS data set variable whose values are plotted on the X axis, which creates the horizontal axis.
Y axis	the axis that specifies height in the coordinate system. The second value in an x,y,z coordinate set represents a location in space relative to the Y axis.
Y variable	the SAS data set variable whose values are plotted on the Y axis, which creates the vertical axis.
Z axis	the axis that specifies depth in the coordinate system. The third value in an x,y,z coordinate set represents a location in space relative to the Z axis.
Z variable	the SAS data set variable whose values are plotted on the Z axis, which creates the depth axis.

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