The Wafer fit displays surface data in a direct format. The collected data are organized in (x,y,z) triples. The (x,y) values specify a grid location, and the z value specifies the value at that grid point. If there are multiple values with the same (x,y) values, all the corresponding z values are averaged so that there is just one value for every (x,y) pair. The surface is constructed by creating triangles between the individual points and then plotting these triangles with standard surface plot techniques. Only the raw data are used, (i.e., no interpolation or extrapolation is used). The resulting plot can be displayed either in 3D form as a surface or in 2D form as a contour plot.