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The G4GRID Procedure


The G4GRID procedure creates a SAS data set to be used with the SAS/SPECTRAVIEW three-dimensional visualization software. The procedure enhances SAS/SPECTRAVIEW software's ability to create two- and three-dimensional graphic images from data.

PROC G4GRID allows you to interpolate three-dimensional data contained in a SAS data set. While PROC G4GRID is not required to load a data set into SAS/SPECTRAVIEW, the procedure does provide advantages:

PROC G4GRID works by interpolating randomly distributed points in three dimensions and by creating a volume grid with data points at each grid location. The procedure uses a Gaussian interpolation function that varies as the inverse of the square of the distance from surrounding data points. While PROC G4GRID is similar in syntax and function to the G3GRID procedure, G4GRID uses a different interpolation method and does not render the same values as G3GRID.

You can run the procedure using either of these methods:

Data Considerations

Each data set processed by the G4GRID procedure must contain at least four numeric variables:

If you specify more than one response variable, the procedure performs a separate analysis and produces interpolated values for each response variable. Unlike the G3GRID procedure, the G4GRID procedure does not require that the input data coordinate values be unique. It uses all coordinate values that fall within the grid volume.


The following terms are specific to the G4GRID procedure:
coordinates the values representing the location of a data point along the X, Y, Z axes.
interpolate to estimate values between two or more known values.
response a value representing a measured response associated with each data point in the volume.
variables the SAS data set variables whose values are plotted on the X, Y, and Z axes.

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