Linear spline

FemtoScan software can calculate bilinear cubic splines for the surfaces and subtruct splines from the surfaces. To construct a spline the surface divided into rectangels, sides of which user can input in dialog window. This window appeared when user choose command Spline/ BSpline stride.... For every rectangle average surface height is calculated, and spline constructed on the central point of the rectangles, where Z-axis values are average heights calculated before. To construct a spline for a surface or its part, choose command Spline/ Bilinear spline. To substruct spline from the surface or its part, choose command Spline/ BSpline fit. Note, that command BSpline fit calculate spline, substructed from the surface, and it do not use spline, calculated with the command Bilinear spline.