Parametric Freehand Sketches

In this paper we present the 2D parametric freehand sketch component of an experimental prototype called GEGROSS (GEsture & Geometric ReconstructiOn based Sketch System). The module implements a gesture alphabet and a calligraphic interface to manage geometric constraints found in 2D sections, that are later used to perform modeling operations. We use different elements to implement this module. The geometric kernel stores model data. The constraint manager 2D DCM handles restrictions. Finally, we use the CALI library to define gestural interfaces. In this paper we present a strategy for integrating these tools, and a calligraphic interface we developed to provide dimensional controls over freehand sketches. Our system allows users to build simple sketches composed by line segments and arcs, which are automatically tidied and beautified. Proportional and dimensional information over sketched parts is provided by handwriting their corresponding sizes.