This paper introduces methods of creating, modifying and visualizing free-form geometric models, by use of the B-spline hyperpatch. Modeling tools for the hyperpatch, including local control-point interactions, lofting operations and sweeping operations, are described. These operations, together with modeling tools generated for free-form surface design, form a powerful tool hierarchy for the design of complex solids. Techniques are also described by which these hyperpatches may be integrated into conventional visible-surface algorithms. With the defined methods, and the hyperpatch model, the complexity of free-form solid object construction was found to be significantly simplified.
