Modeling and Rendering with eXpressive B-Spline Curves

Abstract

eXpressive B-Spline Curve (XBSC) is a resolution-independent and computationally efficient technique for vector-based stroke modeling and rendering with the flexibility in defining and adjusting the shape and other parameters of the stroke. It generalizes the existing Disk B-Spline Curve (DBSC) geometric representation, which itself is a generalization of the Disk Bézier curve. XBSC allows flexible shape and color manipulation and rendering of strokes with asymmetrical shape control and rich color management. These properties make XBSC suitable for modeling freeform stroke shapes and animation, specifically in squash and stretch, a common technique to bestow elasticity and flexibility in shape changes. During the squash and stretch animation computation, we constrain the shape of the XBSC stroke to conserve its area. To achieve this, we apply the simulated annealing algorithm to iteratively adjust the XBSC while maintaining its area. We show several drawings, rendering and deformation examples to demonstrate the robustness of XBSC.