Method
Observations with missing values for Z, Y, X variables are not used.
If there are observations that all share the same values for the X and Y variables, then the mean Z value of the set is used for the purpose of fitting a surface to the data set.
Clicking on the Method button in the variables dialog displays the dialog in Figure 37.3.
Figure 37.3: Rotating Plot Methods Dialog

Grid Size: Horizontal Size 
specifies the horizontal resolution of the rectangular grid over which surface and ZColor functions are evaluated. 
Grid Size: Vertical Size 
specifies the vertical resolution of the rectangular grid over which surface and ZColor functions are evaluated. 
Fit:Linear Interpolation 
linearly interpolates surface and ZColor functions across rectangular grid cells. 
Fit:ThinPlate Smoothing Spline 
fits surface and ZColor functions over the rectangular grid using thinplate smoothing spline fitting. The process may be much slower than linear interpolation. It usually produces very smooth surfaces and colors.

Number of Contour Levels 
specifies the number of contour levels to be drawn on the surface. The contour levels are spaced evenly within the range of the ZColor variable, or the range of the Z variable if no ZColor variable is specified. 
Copyright © 2007 by SAS Institute Inc., Cary, NC, USA. All rights reserved.