To really understand the concept of fairing surfaces it may be helpful to look at how lines fairing was done historically. The draftsman would use a rod (or: batten), bend it and place weights on it to fix its shape. The more curvature was needed, the more weights were needed to hold the rod in position or a more flexible rod had to be chosen. Adding more weights on top of the rod, would also make it easier for unfairness (i.e. inflexions in the curve) to arise. To prevent that, the draftsman would lift each weight up, let the rod “relax” and put the weight down again. With this procedure, he would iterate to obtain the required shape. Instead of adding more weight to areas of high curvature, the draftsman could also choose to use a rod with less stiffness. The disadvantage of that is that the flexible rod would make it very difficult to fair parts of the curve with less curvature. Ultimately, the experienced draftsman would look for the stiffest rod and use as few weights as possible to obtain the required shape.

In Maxsurf, a B-spline surface can be seen as the rod and the control points as the weights. (See Basic Principles in the Maxsurf manual).

Start learning fairing in Maxsurf in the section on Displaying Curvature.