10.1184/R1/6607097.v1 William Welch William Welch Michael Gleicher Michael Gleicher Andrew Paul. Witkin Andrew Paul. Witkin Manipulating surfaces differentially Carnegie Mellon University 1987 Computational geometry. CAD/CAM systems. 1987-06-01 00:00:00 Journal contribution https://kilthub.cmu.edu/articles/journal_contribution/Manipulating_surfaces_differentially/6607097 Abstract: "We want to create interactive surface design systems which provide intuitive interfaces to parametric surface representations. In this paper, we show how the technique of Differential Manipulation can be used in constructing such interfaces. It allows surface manipulation issues to be treated separately from surface representation issues. Arbitrary differentiable functions of representation parameters can be used to control the surface. Constraint and optimization techniques can be used to enhance interaction and control many surface degrees of freedom at once. We provide examples of the technique's use in our interactive surface modeling program."