Demarcating curves for shape illustration

Abstract

Curves on objects can convey the inherent features of the shape. This paper defines a new class of view-independent curves, denoted demarcating curves. In a nutshell, demarcating curves are the loci of the "strongest" inflections on the surface. Due to their appealing capabilities to extract and emphasize 3D textures, they are applied to artifact illustration in archaeology, where they can serve as a worthy alternative to the expensive, time-consuming, and biased manual depiction currently used.

3D Line Drawing for Archaeological Illustration

“…Compared with the demarcating curves in Fig. 17(c) using the method (Kolomenkin et al 2008), the generated 3D line drawing in Fig. 17(d) has more accurate geometric information while both results are comparable visually.…”

“…The most common view-independent lines are ridges and valleys (Ohtake et al 2004;Yoshizawa et al 2005), which are defined as the loci of points where the principal curvatures take extrema along their corresponding principal directions. Demarcating curves are recently applied to artifact illustration in archaeology, which are defined as the loci of the strongest inflections on the surface (Kolomenkin et al 2008). They typically separate ridges and valleys on 3D models.…”

Efficient and robust 3D line drawings using difference-of-Gaussian

“…To improve the performance, Zhang et al [13] presented a GPU method to compute PELs in real time. Kolomenkin et al [4] defined demarcating curves as the zeros of the normal curvature in the curvature gradient direction. Later, Kolomenkin et al [14].…”

“…11, the letters on the scanned Hellenistic stamped amphora handle are difficult to read with the proposed DoG/ADoG lines. The demarcating curves [4] are the loci of the strongest inflections on the surface, and more effective than DoG/ADoG lines for artifact illustration in archeology. One possible way to improve DoG/ADoG lines is to enhance the contrast of the illumination (e.g.…”

“…The object-space algorithms, e.g., suggestive contours [1], apparent ridges [2], PELs [3], demarcating curves [4], Laplacian lines [5], etc., adopt a two-pass algorithmic framework: in the first pass, certain geometric properties (such as curvatures, principal directions and their derivatives) are computed for each vertex and the geometry of the feature lines are extracted; then the extracted lines are rendered in the second pass by iterating the mesh triangles or edges. In spite of its popularity, this two-pass framework usually requires that the input model is smooth and has good triangulation quality, since computing high order geometric properties using discrete differential geometry is very sensitive to mesh tessellation and noises.…”