Journal for Geometry and Graphics 09 (2005), No. 2, 177--189
Copyright Heldermann Verlag 2005
A Sketch Interpreter System with Shading and Cross Section Lines
Kunio Kondo
Dept. of Information and Computer Sciences, Saitama University, 255 Shimo-okubo, Saitama 338-8570, Japan
kondo@ke.ics.saitama-u.ac.jp
Haruki Shizuka
Dept. of Information and Computer Sciences, Saitama University, 255 Shimo-okubo, Saitama 338-8570, Japan
Weizhong Liu
Dept. of Information and Computer Sciences, Saitama University, 255 Shimo-okubo, Saitama 338-8570, Japan
Koichi Matsuda
Faculty of Software and Information Science, Iwate Prefectural University, 152-52 Aza-sugo, Takizawa-mura, Iwate-gun 020-0173, Japan
matsuda@soft.iwate-pu.ac.jp
We present a sketch interpreter system with shading and cross section lines for 3D freeform design. The input strokes are classified into three types: outlines (contour lines), shading lines and cross section lines. The outline is used to generate the basic rounded shape. The shading lines and cross section lines are used as control lines that are drawn inside the contour to modify the 3D shape. In order to effectively extract 3D information from the shading and cross section lines, we analyze different representations and deformations of the shading and cross section lines and classify them into three cases: convex, concave and 'upheaving'. Each deformation is drawn by hand and transferred to a 3D shape according to the rules proposed in this paper. We evaluate our sketch interpreter system for various objects from concept sketches and present our results.
Keywords: Sketch, freehand drawing, shading, cross section lines.
MSC: 68U05
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