Pay attention to the 'Flow' of the CVs
A smooth and regular 'flow' of CVs will ensure that your curves have:
Smoothness – no unwanted 'kinks'.
Good Acceleration – a consistent change of curvature giving good highlights.
No unwanted inflections – where curvature switches from concave to convex.
Most users simply judge the flow of CVs and Hulls to be 'regular and disciplined' (or not) by eye. Here are some examples:
Applying the Rule The easiest way to ensure a good flow of CVs is to start with a curve with very few CVs, for example a single-span degree 2 or 3. Try to match your design, and only increase the number of CVs gradually until you get just enough to achieve your desired shape.
Flow 'Flow' can be defined as the relationship between all CVs, from one CV to the next. In particular we look at two variables: the spacing between each CV and the distance of each CV from the curve or surface. Spacing (Hull Length) The relative spacing between CVs should change smoothly. If we measured the distance between neighbouring CVs, and plotted that onto a graph, we would expect the values to change in one of the following ways: Be constant Gradually increase Gradually decrease If the values increase and decrease erratically, then this could be described as poor 'flow'.
Distance (CV from curve) The distance that the CV lies away from the curve should also change smoothly as you travel along the curve.
