Displays a dialog box that allows you to specify the size and number of intervals in a generated rectangular grid of 3D points based on the current 3D surface plot.
This routine uses one of two methods to generate Z values. Quadratic interpolation (in general) produces a smoother surface than what is typically displayed with randomlyspaced points. In many cases the resulting grid is a more accurate representation of the input than the triangularmesh plot, but it should also be obvious to the user that no algorithm can make up for sparse data. Quadratic interpolation weights the result by the inverse of the square of the distance to the nearest Control points points. Planar interpolation simply maps each generated point to the planar surface of the triangle containing the point. The generated surface will not be as smooth as one produced by quadratic interpolation.
Extrapolate points outside convex hull
Disabled for planar interpolation. If checked, DPlot will generate values for the entire extents (specified with the from and to boxes). Depending on the complexity of the existing surface near the edges, these extrapolated values may be, at best, questionable. If this box is unchecked, values outside the limits of the triangular mesh are set to 1.E+38, which in turn causes DPlot to ignore them.
Control points
The number of points used to interpolate with the quadratic method. In most cases the default value of 4 works nicely. However in some cases more points are needed to smooth the resulting plot.

Related macro commands 
Page url:
https://www.dplot.com/help/index.htm?helpid_generate_mesh.htm