Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transaction on Visualization and Computer Graphics, 1(3):231--239, September 1995.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....generate texture coordinates from viewport coordinates, the textures seem to stay above the object thus limiting the techniques suitability for animations. In [5] attributed lines in object space were used to augment traditional renderings with regard to userdefined importance of information. In [39, 8, 9, 15] 3D curves on free form surfaces and parametric or implicit surfaces were introduced to emphasize geometric properties of 3D models. Winkenbach and Salesin [38] also presented an object based approach, in which oriented strokes were utilized to simulating different tones. Markosian et al. 25] ....

G. Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transactions on Visualization and Computer Graphics, 1(3):231-- 239, 1995.

....the particular marks is crucial to build generic modules. Most mark system using orientation attributes can be used to display any 2D vector field, e.g. pen and ink strokes [SWHS97] streamlines [TB96] or LIC [CL93] 3D 3D orientation computation have been proposed using iso parametric curves [Elb95] or principal curvatures [ZH00] 3D 2D [ST90] Similarly, 2D exist, e.g. RK00] The 2D 2D category offers both automatic [Hae90, Hau01] and user controlled [Hae90, Ost99, SWHS97] approaches. 6.4 Mark The mark system is the last representational aspect. It deals with the physical medium ....

G. Elber. Line art rendering via a coverage of isoparametric curves. IEEE Trans. on Visualization and Computer Graphics, 1(3):231--239, September 1995.

....particular marks is important to build generic modules. Most mark system using orientation attributes can be used to display any 2D vector field, e.g. pen and ink strokes [SWHS97] streamlines [TB96] or LIC [CL93] 3D # 3D orientation computation have been proposed using iso parametric curves [Elb95] or principal curvatures [ZH00] 3D # 2D [ST90] Similarly, 2.5D # 2D exist, e.g. RK00] The 2D # 2D category offers both automatic [Hae90, Hau01] and user controlled [Hae90, Ost99, SWHS97] approaches. 5.4 Marks The mark system is the last representational aspect. It deals with the ....

Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transactions on Visualization and Computer Graphics, 1(3):231--239, September 1995. ISSN 10772626.

....available for triangle meshes that can be utilized for producing strokes. Our results will show that rendering can be performed efficiently on such free form geometry. The preceding survey is continued with focus on automatically generating strokes from 3D geometry. 1. 2 Related work [Elber95] uses a coverage of isoparametric curves of a free from surface for line art rendering. Therefore strokes are defined as a parallel lines in the parameter domain resulting in isoparametric curves. This works especially well with surfaces of revolution. Winke96] uses such isoparametric lines in ....

Elber, G.: Line Art Rendering via a Coverage of Isoparametric Curves, IEEE Transactions on Visualization and Computer Graphics, Vol. 1,No. 3, 1995

....certain aesthetic appeal. However, Leister s method produces very stylized illustrations, is not able to adequately convey subtle variation in shading, and does not allow texturing. Along a similar vein, Elber presented an algorithm to render NURBS surfaces with a coverage of isoparametric curves [10]. Shading is conveyed by adjusting the density of the isoparametric curves as a function of the illumination on the surface. One drawback of Elber s method is that it does not 5 reproduce smooth variations in shading well. In addition, Elber did not address more fundamental issues in pen and ink ....

Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transaction on Visualization and Computer Graphics 1, 3 (September 1995), 231--239.

....at 300 dpi. just the geometry or the photometric qualities of their designs Much of the effort in NPR is directed towards imitation of traditional art materials and techniques: sumi e [27] and watercolor [5] paintings, pen and ink illustrations [22, 35, 36, 23] pencil drawings [30] engravings[20, 7, 8] and copper plates[14] While the modeling of art materials allows designers to generate images that resemble traditional illustration styles, we share the view of Landsdown and Schoffield[13] and believe that it is more important to create rendering styles specific to computer generated artistic ....

....surface directions are highlighted. Even though many NPR algorithms generate black and white images they do not use the results of conventional halftoning. The issue of tone reproduction is either ignored [1, 12, 6, 29] or is addressed by an alternative often computationally expensive technique [14, 20, 7, 8, 22, 35]. In this work we follow a different approach and extent the conventional halftoning to non photorealistic rendering. A similar approach was taken by Ostromoukhov and Hersch[17] who modified ordered dithering and enabled artists to design single screen elements. Buchanan[4] introduced a variety of ....

Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transactions on Visualization and Computer Graphics, 1(3):231--239, September 1995. ISSN 10772626.

....and tone of the model. They extended their work to resolution dependent hatchings and developed methods for interactive and automatic definition of stroke directions within the textures. In [30] the approach was applied to parametric surfaces. Elber presented line art images of NURBS surfaces in [4]. A disadvantage of both approaches is that lines are directed along parameter directions which leads to problems if parametrization changes between patches or, as in the case of triangular surfaces, parametrization is not given explicitly. Recently, Elber presented a more general but still ....

G. Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transactions on Visualization and Computer Graphics, 1(3):231--239, September 1995.

....a surface in general position, these fields are always globally defined, excluding a set of isolated singularities. to isometric, i.e. minimizes the metric distortion as described in, for example, 10, 27] In this case, parametric lines are close to geodesics. Isoparametric lines were used by [36, 11]. Artistic examples. We observe that artists tend to use relatively straight hatch lines, even when the surface has wrinkles. Smaller details are conveyed by varying the density and the number of hatch directions (Figure 9) Figure 9: Almost all hatches in this cartoon by Thomas Nast curve ....

Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transactions on Visualization and Computer Graphics, 1(3):231--239, September 1995.

....materials and resemble hand draw strokes. During shading the strokes are mapped to image space together with the corresponding polygons and are used for tone mapping then. This system was extended to process free form surfaces in [20] where isoparametric curves are used for rendering, following [5]. Such curves look especially well for surfaces of revolution. Elber also employs lines of curvature of parametric surfaces and contour lines of implicit surfaces [6] By precalculating these stokes and applying a simple shader even interactiveness can be achieved [7] Most recently, 21] ....

....shapes usually exploit the di#erential geometric attributes of the surfaces. Grids of principal curvature directions and geodesic lines provide natural (orthogonal) parameterizations for freeform surfaces and the strokeline orientation can be based on the iso lines of such parameterizations [5, 6]. For piecewise linear surface representations these concepts have to be generalized. By locally fitting a polynomial patch to a mesh vertex and its adjacent neighbors, we can compute first and second fundamental forms for each vertex [18, 13, 17] From these we can derive normal and principal ....

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Gershon Elber. Line Art Rendering via a Coverage of Isoparametric Curves. IEEE Transactions on Visualization and Computer Graphics, Vol. 1, No. 3, September 1995, pp. 231--239

....paint [2] and the effects of bristle brushes on painting and calligraphy [30, 36] also bears relation to the work described here, in providing a plausible simulation of traditional artists tools. 1 The work described here also continues in a growing line of non photorealistic rendering research [5, 6, 9, 16, 22, 23, 26, 33, 39, 40], and it builds on previous work on animating the fluid dynamics of water [1, 10, 19] and the effects of water flow on the appearance of surfaces [7, 8, 28] 1.2 Overview The next section describes the physical nature of the watercolor medium, and then goes on to survey some of its most ....

Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transaction on Visualization and Computer Graphics, 1(3):231--239, September 1995.

....paint [2] and the effects of bristle brushes on painting and calligraphy [30, 36] also bears relation to the work described here, in providing a plausible simulation of traditional artists tools. 1 The work described here also continues in a growing line of non photorealistic rendering research [5, 6, 9, 16, 22, 23, 26, 33, 39, 40], and it builds on previous work on animating the fluid dynamics of water [1, 10, 19] and the effects of water flow on the appearance of surfaces [7, 8, 28] 1.2 Overview The next section describes the physical nature of the watercolor medium, and then goes on to survey some of its most ....

Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transaction on Visualization and Computer Graphics, 1(3):231--239, September 1995.

....changes tone and character. rithm to implement this process. This algorithm, which is essentially a discontinuity sensitive reconstruction filter, is the main technical contribution of the paper. 1.1 Related work Line art illustration has been explored previously by a number of authors. Elber [9], Saito and Takahashi [21] Winkenbach and Salesin [27] Strothotte et al. and Lansdown and Schofield [14] all use 3D models to generate illustrations. Pneuli and Bruckstein [20] and Salisbury et al. 23] both generate illustrations starting from grey scale images. However, neither of these ....

Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transactions on Visualization and Computer Graphics, 1(3):231--239, September 1995.

....we describe a new resampling algorithm to implement this process. This algorithm, which is essentially a discontinuity sensitive reconstruction filter, is the main technical contribution of the paper. 1.1 Related work Line art illustration has been explored previously by a number of authors. Elber [9], Saito and Takahashi [21] Winkenbach and Salesin [27] and Lansdown and Schofield [13] all use 3D models to generate illustrations. Pneuli and Bruckstein [20] and Salisbury et al. 23] both generate illustrations starting from grey scale images. However, neither of these works addresses the ....

Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transactions on Visualization and Computer Graphics, 1(3):231--239, September 1995.

....techniques to create illustrations from 3D models. Piranesi uses a standard graphics pipeline to create a 2D reference image akin to a G buffer. The user is then allowed to select specific regions of the image and apply textures that emulate natural media interactively or automatically. Elber [5] described an algorithm to cover NURBS surfaces with isoparametric curves, thus emulating a form of line art rendering. However, his approach does not address a number of the issues in penand ink illustration considered in this paper, such as building tone with stroke textures, outlining objects ....

Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transaction on Visualization and Computer Graphics, 1(3):231--239, September 1995.

....including their ability to abstract away detail, clarify shapes, and focus attention. In recent years, a number of systems have been built to produce illustrations in a pen and ink style. These systems can be classified into two broad categories, depending on their input: geometry based systems [1, 2, 7, 12, 16, 17, 18], which take 3D scene descriptions as input; and image based systems [10, 13] which produce their illustrations directly from greyscale images. The main advantage of geometry based systems is that because they have full access to the 3D geometry and viewing information they can produce ....

Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transactions on Visualization and Computer Graphics, 1(3):231--239, September 1995.

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Gershon Elber. Line art rendering via a coverage of isoparametric curves. IEEE Transaction on Visualization and Computer Graphics, 1(3):231--239, September 1995.

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Elb95. G. Elber. Line art rendering via a coverage of isoparametric curves. IEEE Trans. on Visualization and Computer Graphics, 1(3), September 1995.

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