Approximation of logarithmic spirals

Abstract The radius of curvature of a logarithmic spiral is proportional to its arc length, a property that is desirable for the design of aesthetic curves. We describe a method for approximating logarithmic spiral segments by rational cubic spline curves. This approach provides the tools for the construction of planar spline curves whose curvature radius plot is continuous and close to piecewise linear. A number of examples illustrate the approximation method.