Computer Drawing Tools for Assisting Learners, Hobbyists, and Professionals
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Drawing is the earliest form of visual depiction. The goal of this thesis is to facilitate and accelerate drawing for amateurs as well as for expert designers and illustrators, employing graphics, image processing and interaction techniques. As this is a broad spectrum to tackle, we identify three specific problems related to drawing, and propose computer tools to help users to overcome the main challenges on each domain. In Chapter 2 we present an interactive drawing tool to help people practice traditional drawing-by-observation techniques. We build this tool supported by a number of techniques to help people gain consciousness of the shapes in a scene. We automatically extract visual guides from a model photograph. The tool's interface displays these information and offer corrective feedback to guide its manual reproduction. In Chapter 3 we propose a method to help designers to enrich their drawings with color and shading. Professionals frequently draw curvature lines to convey bending of smooth surfaces in concept sketches. We exploit this information and extrapolate curvature lines in a rough concept sketch. This extrapolation allows us to recover the intended 3D curvature field and surface normal at each pixel, to create shading and texturing on top of the sketch. In Chapter 4 we propose a tool that helps users to fabricate wire wrapped jewelry. Analogous to physical 3D drawing, this form of handmade jewelry can be seen as taking sketches into the physical world. The presented method assist the user in the main challenges of creating 2D wire-wrapped jewelry from a 2D drawing: decomposing the input into a set of wires, and bending the wires to give them shape.