ProcessData()data.pts and data.grd components of Data. 
The data.pts component is a data frame with variables:data.raw.x and y coordinates.x and  
  y directions, respectively (optional).data.grd component is a list with components:z are measured.x and y directions, 
  respectively.x and y 
  directions, respectively (optional).Data and 
include: cols, vars, data.raw, data.pts, 
data.grd, lim.data, poly, poly.data, 
poly.crop, grid.dx, grid.dy, mba.m, mba.n, 
and mba.h (see Data).
A data frame based on the user-defined state variables is first created. 
Records outside the user-defined spatial and temporal domains are then removed 
using: (1) data limits, where the x, y, z, and t 
limits are specified in the xlim, ylim, zlim, and 
tlim components of the lim.data list, respectively; and (2) a 
two-dimensional polygon defining the spatial domain within the xy-plane.
An interpolated grid of z values in constructed using a 
Multilevel B-spline approximation. The spatial extent of the interpolated 
surface is constrained using polyLimit, a polygon that sets spatial 
limits for grided data; where z values corresponding to grid nodes located 
outside this polygon are set to NA.mba.points