Sketch-Based Interfaces for Parametric Modelling

Abstract

Sketching is still widely used by designers and engineers as it continues to be a useful and powerful tool that helps designers during the conception of a new product (Tversky, 2002). If engineers and designers generally use sketches the question is, why sketching is not integrated in the digital design process? Available Graphical User Interfaces (GUI) for CAD applications are still by and large constrained by the WIMP (Windows, Icons, Menus and Pointing) paradigm and current commercial CAD systems not support sketch-based design. Therefore, the problem is that the sketches continue to be unplugged to the rest of the design process. In other words, in spite of recent advances in Computer Aided Design, current CAD tools are not well suited to the initial design stages of product development, because many techniques and idioms characteristic of hand-made drawings cannot be used directly in CAD systems. To sum up, there is a disconnection between sketching and CAD tools in the new product development process and true Computer-aided Sketching (CASk) tools are required. During last decades different research lines have been explored to improve the humancomputer interface in CAD systems. In this context, some CASk systems have been developed to support freehand drawings as a way to create and edit three-dimensional geometric models. These advanced CASk systems try to provide more functionality than paper or a whiteboard, giving an added value to sketching on a digital environment. This extra functionality usually has been directed either to improve the graphic quality of the sketch by means of a beautification process or it has been oriented to automatically transform the 2D sketch into a 3D model. Interest in CASk systems has increased in the last years as new hardware devices such as Tablet-PCs and LCD graphics tablets have been launched to the market.