Fitting 2D B-splines with draft angle to point data

Ensuring that geometric models have the required draft angle is very important for many manufacturing applications. In this paper an algorithm is presented that ensures that 2D B-splines fitted to point data will have a specified draft angle. First, sufficient conditions are derived that will be used as constraints in the least squares fitting of B-splines to the point data. A Least SQuares fitting algorithm with Draft Angle Constraints (LSQ-DAC) is developed. The algorithm is compared to two non-linear programming methods, the Augmented Lagrange Multiplier method and the Sequential Quadratic Programming method. The paper concludes with a case study showing the application in 3D.