G. Winkenbach and D.H.Salfi:4U "Rendering Parametric Surfaces in Pen and Ink," Proc. SiggraN 96, ACM Press, 1996, pp. 469-476.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... Winkenbach and Salesin defined intricately detailed resolution independent fine stroke textures [42] and showed how they could be applied in accordance with the directions of the surface parameterization to represent a class of curved surfaces in the style of a pen and ink illustration [43]. Other textures that follow the surface in some sense include the reaction diffusion textures proposed by Turk [38] and Witkin and Kass [45] Most 3 recently, Turk and Banks [39] described a method for evenly distributing streamlines over a 2D vector field to represent the flow in a visually ....

Georges Winkenbach and David H. Salesin. "Rendering Parametric Surfaces in Pen and Ink", Computer Graphics Proceedings, Annual Conference Series, 1996, pp. 469-476.

....manifolds, three dimensional surfaces in particular. Examples of this are texture synthesis [97, 104] vector field visualization [25] and weathering [26] In addition, data defined on surfaces often needs to be regularized, e.g. as part of a vector field computation or interpolation process [78, 101], for inverse problems [33] or for surface parameterization [27] These last examples can be addressed by solving a variational problem on the surface, or its corresponding gradient descent flow on the surface, using for example the theory of harmonic maps [29] which has recently been ....

G. Winkenbach and D. H. Salesin, "Rendering parametric surfaces in pen and ink," Computer Graphics (SIGGRAPH 96), pp. 469-476, 1996.

....thousands, of lines. Implicit surfaces can be obtained for example from the algorithms in [44, 65, 177, 183, 200] Applications of PDE s on surfaces include computer graphics [184, 185, 194] visu 35 alization [40] weathering simulation [41] vector field computation or interpolation process [153, 191], inverse problems [58] and surface parameterization [43] We assume then that the three dimensional surface of interest is given in implicit form, as the zero level set of a given function qt: q3 q. This function is negative inside the closed bounded region defined by , positive outside, ....

Winkenbach, G. and Salesin, D.H., Rendering parametric surfaces in pen and ink, Computer Graphics (SIGGRAPH 96), 469-476 (1996). 61

....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. Winkenbach and D. Salesin. Rendering parametric surfaces in pen and ink. Computer Graphics (SIGGRAPH 96 Proceedings), pages 469-- 476, 1996.

....a hand painted appearance from a photograph and an approach to designing styles of illustration. They demonstrated a technique for painting with long, curved brush strokes, aligned to the normals of image gradients, to explore the expressive quality of complex brush stokes. Winkenbach and Salesin [32] presented algorithms and techniques for rendering parametric free form surfaces in pen and ink. Deussen et al. 5] used points for computer generated pen andink illustrations in simulating the traditional stipple drawing style. Their method is to first render polygonal models into a continuous ....

G. Winkenbach and D. Salesin. Rendering parametric surfaces in pen and ink. In Proceedings of SIGGRAPH 1996.

....research has shown that such illustrations can be easily produced, consume less storage and thus can be a better choice than photorealism in many applications. Research in non photorealistic rendering (NPR) has found methods to simulate the effects of various traditional media like pen and ink [4, 27, 28, 34, 35, 19], pencil sketches [1] water color [3] and engraving [21, 30] There has been work on rendering different styles like impressionism [8, 10, 15, 18] and technical illustrations [6, 26, 25] There has also been work on non photorealistic rendering of specific objects like fur and grass [13, 14] To ....

....system used luminance and hue shifts to create such lighting effects. We also use contrast enhancement while creating charcoal rendering effects. We achieve this by using a contrast modifying function which we call the contrast enhancement operator (CEO) Similar techniques have also been used in [32, 31, 29, 27, 28, 34, 35] where the problem is viewed as a special kind of half toning. The contribution of our technique lies in the fact that we achieve many different effects of charcoal rendering using the common framework of contrast enhancement. The enhancement operator operates on a uniform noise texture to ....

Georges Winkenbach and David H. Salesin. Rendering Parametric Surfaces in Pen and Ink. In SIGGRAPH 96 Conference Proceedings, pages 469--476, August 1996.

....has shown that such illustrations can be easily produced, consume less storage and thus can be a better choice than photorealism in many applications. Research in non photorealistic rendering (NPR) has found methods to help artists generate imagery in various traditional media like pen and ink [4, 25, 26, 28, 29, 17], pencil sketches [1] water color [3] and engraving [19, 27] There has been work on rendering different styles like impressionism [8, 10, 14, 16] rendering of fur and grass [12, 13] and technical illustrations [6, 24, 23] However, to the best of our knowledge, except for an interactive 2D ....

Georges Winkenbach and David H. Salesin. Rendering Parametric Surfaces in Pen and Ink. In SIGGRAPH 96 Conference Proceedings, pages 469--476, August 1996. 12

....Renderering paper [16] These were soon followed by commercial tools such as Fractal Painter [3] Since then, there has been an explosion of new styles presented at SIGGRAPH and other venues. Just a few examples include impressionist painting [12] technical illustration [5] pen and ink [17], engraving [14] watercolor, and even the style of Dr. Seuss [9] As stylized renderers improved in performance due to hardware advances and clever algorithms, interactive stylized rendering became practical. An early example was demonstrated in the Sketch system [18] that employed a sketchy ....

Georges Winkenbach and David H. Salesin. Rendering parametric surfaces in pen and ink. Proceedings of SIGGRAPH 96.

....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 order to produce high quality illustrations like in [Winke94] Interestingly, for this approach the surface is tessellated to a polygonal mesh for the final tone mapping as well. Most recently [Elber99] extends these techniques to enable interactive rendering ....

....uniform distribution. Regions of high curvature of the mannequin head are rendered with higher density of strokes. 3.2 Shading and rendering The line art shader is restricted to black and white only. There are different approaches possible depending on the requested quality of the output. While [Winke94, Winke96] use sophisticated shading in conjunction with a special tone mapping process, our shader is relatively simple much like the one used in [Elber99] Therefore real time applications are practicable. In general any advanced shader can be used. We are not limited to a particular shading resp. ....

Winkenbach, G.; Salesin, D.H.: Rendering Parametric Surfaces in Pen and Ink, Computer Graphics (Proc. SIGGRAPH '96), pp. 469-467, 1996

....how to turn a photograph into a watercolor, charcoal, colored pen, oil paint picture, or engraving leaving the user an opportunity of controlling the appearance of the picture by adjusting the control parameters. For example, rendering parametric free form surfaces in pen and ink is proposed in [24]. Interactive creating pen andink line style drawings from gray scale images is introduced in [21] Various artistic effects of watercolor and their automatic simulation are described in [4] Line art drawing is studied in [5 8,11,19] Expressive rendering is proposed in [10,12] In [14] digital ....

Winkenbach G and Salesin D (1996) Rendering Parametric Surfaces in Pen and Ink. SIGGRAPH 96, Computer Graphics Proceedings, pp 469-476.

.... 3D models of arbitrary topology (6) 2 Previous work Much of the work in non photorealistic rendering has focused on tools to help artists (or non artists) generate imagery in various traditional media or styles such as impressionism [5, 12, 14] technical illustration [4, 19, 20] pen and ink [1, 21, 22, 26, 27], and engraving [16] Our work is applicable over a range of styles in which individual strokes are visible. One way to categorize NPR methods would be to consider the form of input used. One branch of stroke based NPR work uses a reference image for color, tone, or orientation, e.g. 5, 21, 22] ....

....and Perlin [6] addressed the challenge of frame toframe coherence by applying optical flow methods to approximate object space coherence for strokes. Our work follows a branch of research that relies on 3D models for input. Much of the work in 3D has focused on creating still images of 3D scenes [1, 2, 20, 24, 25, 26, 27]. Several systems have also addressed off line animation [1, 14] wherein object space stroke coherence is considerably easier to address than it is for processing of video. A number of researchers have introduced schemes for interactive non photorealistic rendering of 3D scenes, including ....

WINKENBACH, G., AND SALESIN, D. H. Rendering parametric surfaces in pen and ink. Proceedings of SIGGRAPH 96, 469--476.

.... 2 Previous work Much of the work in non photorealistic rendering has focused on tools to help artists (or non artists) generate imagery in various traditional media or styles such as impressionism [8, 9, 16, 18] technical illustration [6, 23, 24] watercolor [2] engraving [20] and pen and ink [3, 26, 27, 31, 32]. Our work is applicable over a range of artistic styles in which individual hatching strokes are visible, for example pencil, charcoal, or crayon. One way to categorize NPR methods would be to consider the form of input used. A branch of stroke based NPR work uses a reference image for color, ....

....and Perlin [10] addressed the challenge of frame toframe coherence by applying optical flow methods to approximate object space coherence for strokes. Our work follows a branch of research that relies on 3D models for input. Much of the work in 3D has focused on creating still images of 3D scenes [3, 4, 10, 24, 30, 29, 31, 32]. However, several systems have addressed off line animation [1, 3, 18] wherein object space stroke coherence is considerably easier to address than it is for processing of video. A number of researchers have introduced technologies for interactive NPR for 3D scenes, for example, shading for ....

WINKENBACH, G., AND SALESIN, D. H. Rendering parametric surfaces in pen and ink. Proceedings of SIGGRAPH 96, 469--476. 7

....particular. Examples of this are texture synthesis [97, 104] vector field 52 Solving PDE s on Implicit Surfaces 53 visualization [25] and weathering [26] In addition, data defined on surfaces often needs to be regularized, e.g. as part of a vector field computation or interpolation process [78, 101], for inverse problems [33] or for surface parameterization [27] These last examples can be addressed by solving a variational problem on the surface, or its corresponding gradientdescent flow on the surface, using for example the theory of harmonic maps [29] which has recently been ....

G. Winkenbach and D. H. Salesin, "Rendering parametric surfaces in pen and ink," Computer Graphics (SIGGRAPH 96), pp. 469-476, 1996.

.... Illustration Rules Markosian [24] p p p p Dooley [11] p p p p Saito [29] p p p p Driskill [12] p p Elber [13] p p p Seligmann [34] p p p p Land [22] p p p Gooch [15] p p p p Zeleznik [42] p p p Salisbury [32, 31] p p Salisbury [30] p p p Winkenbach [38] p p p Winkenbach [39] p p p Meier [27] p p Haeberli [17] p Litwinowicz [23] Curtis [10] p This Thesis p p p p p Note: Line drawing and shading categories are checked if the work uses shading and line drawing conventions similar to traditional illustration techniques. Automatic means that user ....

....[38] Used by permission. Figure 2.2. Computer generated pen and ink illustrations. 8 2.2 One Shot Images Conveying Shape The research reviewed in the previous section concentrated on generating aesthetically pleasing images. The work done by Seligmann and Feiner [34] Winkenbach et al. [39], Saito et al. 29] Land et al. 22] Elber [13] and Dooley et al. 11] generated images in which the primary goal is to convey shape information. However, these techniques generate single images and do not allow user interaction. Seligmann and Feiner [34] created a system based on the idea ....

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Winkenbach, G., and Salesin, D. H. Rendering parametric surfaces in pen and ink. In SIGGRAPH '96 Conference Proceedings (Aug. 1996).

....textures, images and recursively defined fractals that are drawn along a given path. Salisbury et al. 16] described a method for directing the strokes in line drawings on the basis of vector fields. In their paper they also showed an interactively generated tree image. Winkenbach and Salesin [23, 24] presented a variety of methods for the automatic generation of pen and ink illustrations. In contrast to Strassmann and Hsu et al. they do not work with individual strokes but with artistically elaborate stroke textures. Sasada [17] presented some tree sketches in an architectural environment. ....

G. Winkenbach and D. Salesin. Rendering parametric surfaces in pen and ink. In SIGGRAPH '96 Conference Proceedings, pages 469--476. ACM SIGGRAPH, 1996.

....sense that the silhouette curves may su er some position error; the degree of approximation is determined in part by an adjustable parameter to a curve tracing method, allowing a tradeo of accuracy against speed. 1. SILHOUETTE RENDERING Inspired by non photorealistic rendering (NPR) techniques [9, 10, 3, 14, 11, 13, 7], especially interactive NPR for rapid display of complex polyhedral objects [7] we applied an alternative style of rendering to implicit surfaces. Our basic approach concentrates computational resources on drawing the surface s silhouette quickly and accurately from a given viewpoint, with ....

Georges Winkenbach and David H. Salesin. Rendering parametric surfaces in pen and ink. In Holly Rushmeier, editor, SIGGRAPH 96 Conference Proceedings, Annual Conference Series, pages 469-476. ACM SIGGRAPH, Addison Wesley, August 1996. held in New Orleans, Louisiana, 04-09 August 1996.

....robotic painting device. Unlike Cohen s work, we assume that the composition is provided to the system in the form of an input image to be painted. Hence, we can focus on creating a painterly style, and need not deal with the problem of creativity in designing a composition. Winkenbach and Salesin [20,21] describe a system for automatically creating pen and ink illustrations from 3D models, and Salisbury et al. 16] describe a technique for email: hertzman mrl.nyu.edu ; URL: http: www.mrl.nyu.edu hertzman producing pen and ink illustrations from images. Curtis et al. 5] produce watercolor ....

GEORGES WINKENBACH AND DAVID H. SALESIN. Rendering Parametric Surfaces in Pen and Ink. SIGGRAPH 96 Conference Proceedings, pp. 469-476. August 1996.

....introduced by Salisbury, Winkenbach and Salesin [20, 29, 19] to create hatching lines that represent texture 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 ....

G. Winkenbach and D. Salesin. Rendering parametric surfaces in pen and ink. In H. Rushmeier, editor, SIGGRAPH '96 Conference Proceedings, pages 469--476. ACM SIGGRAPH, Addison Wesley, 1996.

....Image based techniques are presented in [5, 30, 7, 18, 6, 28] these algorithms exploit graphics hardware to produce image precision silhouette images. Our technique is an object space method; it directly uses the 3D representation of objects, rather than their images. Winkenbach and Salesin [36] describe a method for producing appealing pen and ink renderings of smooth surfaces. Parametric lines on NURBS patches were used to determine the hatch directions and silhouette lines were computed using polyhedral approximation to the surface. Their main technical focus is on using the hatch ....

....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 ....

Georges Winkenbach and David H. Salesin. Rendering Parametric Surfaces in Pen and Ink. In SIGGRAPH 96 Conference Proceedings, pages 469--476, August 1996.

....Principal Direction Line Drawings of Arbitrary 3D Surfaces Ahna Girshick Victoria Interrante Department of Computer Science, University of Minnesota girshick, interran cs.umn.edu http: www.cs. umn.edu Research graphics Introduction and Related Work Computer generated line drawings [4,7] are becoming an increasingly popular method of non photorealistic rendering (NPR) While many factors contribute to an effective line drawing quality of line, line placement and density line direction is among the most critical for conveying surface shape. The principal directions hold ....

.... promise in this respect [2] In a human perceptual study, subjects displayed consistent biases toward perceiving surface contours (lines drawn on the surface) as being aligned with the principal directions [5] Despite the potential for principal directions and their suggestion by previous authors [1,2,7], there are currently no available techniques for using them to render viewpoint independent line drawings of arbitrary 3D surfaces. The line drawing algorithm of Markosian et al. 4] handled arbitrary 3D surfaces, but line direction was chosen in a viewpoint dependent manner and lines tended to ....

G. Winkenbach and D. Salesin. "Rendering Parametric Surfaces in Pen and Ink," Computer Graphics (Proc. SIGGRAPH 96), pp.496-476.

....polygonal models. These stroke textures are created for di#erent 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 ....

....to a periodic rule. Adapting the distance of neighboring strokes to the local grey value is not an option since that value usually changes along the stroke but the distance cannot be controlled freely. Many sophisticated techniques have been proposed for the tone mapping in line art images [15, 20, 16]. We use a simple and e#cient technique which does not use any global information but still has flexibility to adjust stroke widths and suppress strokes. The idea is to define strokes to have a constant width w but only a certain portion w # = 1 c) w is drawn in black where c # [c min , c ....

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Georges Winkenbach, David H. Salesin. Rendering Parametric Surfaces in Pen-and-Ink. Computer Graphics (SIGGRAPH '96 Proceedings), 1996, pp. 469--476

....directions 3 RELATED WORK Computer generated 3D line drawings borrow from centuries of artists techniques and have recently received significant attention in the NPR community. Winkenbach and Salesin used stroke textures to create depth and shape in line drawings of parametric surfaces [26]. Markosian et al. emphasized the silhouette edges for viewpoint dependent images of arbitrary 3D surfaces [18] Curtis used 3D models to generate loose and artistic sketches and animations [4] Elber rendered geometrically invariant line drawings and textures of parametric and implicit surfaces ....

.... edges for viewpoint dependent images of arbitrary 3D surfaces [18] Curtis used 3D models to generate loose and artistic sketches and animations [4] Elber rendered geometrically invariant line drawings and textures of parametric and implicit surfaces [6] Principal directions have been suggested [11,26] and approached [2,6] in line drawings. In [26,6] lines were traced along the parametric lines of parametric surfaces, which sometimes coincided with the principal directions. Saito and Takahashi [20] rendered line drawings lines of parametric surfaces along geodesic lines. Interrante et al. 11] ....

[Article contains additional citation context not shown here]

G.Winkenbach and D.Salesin. Rendering Parametric Surfaces in Pen and Ink. Computer Graphics (Proceedings of SIGGRAPH 96), pp.496-476, 1996.

....when the user expects photorealism. In recent years, a few researchers have turned their attention away from photorealism and towards developing non photorealistic rendering techniques in a variety of styles and simulated media, such as impressionist painting [13, 15, 20, 24] pen and ink [28, 33], technical illustration [11, 27] ornamentation [34] engraving [25, 26] watercolor [4] and the style of Dr. Seuss [18] Much of this work has focused on creating still images either from photographs, from computer rendered reference images, or directly from 3D models, with varying degrees of ....

Winkenbach, G., and Salesin, D. H. Rendering parametric surfaces in pen and ink. Computer Graphics (SIGGRAPH 96), 469--476.

.... style renderings of architectural models in which resolution independent stroke textures were applied to planar surfaces [58] and then later extended this work to apply similarly detailed stroke textures to parametrically defined surfaces, 11 following the direction of the parameterization [59]. Salisbury et al. created an interactive penand ink style drawing program in which, among other things, the orientation of the individual elements of a higher level stroke could be specified to follow the direction of the intensity gradient in a two dimensional reference image [47] and then ....

Winkenbach, Georges and David H. Salesin. "Rendering Parametric Surfaces in Pen and Ink", Computer Graphics (proc. SIGGRAPH `96), pp. 469-476.

....of hand drawn images in children s picture books, for example, it appears that simple, brightly colored images that omit subtle detail but clearly delineate important objects appeal better to children than do photographs. The point about communication is also made in a number of recent papers [3, 7, 8, 9, 10, 12, 13, 15, 17, 16]. In our original method, the scene geometry itself does not contain any detail elements such as leaves, blades of grass, etc. which we call graftals. Instead, these are generated each frame just as needed. One benefit of this approach is that no work is expended on processing graftals that are ....

Georges Winkenbach and David H. Salesin. Rendering Parametric Surfaces in Pen and Ink. Proceedings of SIGGRAPH 96, pages 469--476, August 1996. ISBN 0-201-94800-1. Held in New Orleans, Louisiana.

....illustration. Winkenbach and Salesin defined intricately detailed resolution independent fine stroke textures [42] and showed how they could be applied in accordance with the directions of the surface parameterization to represent a class of curved surfaces in the style of a pen and ink drawing [43]. Other textures that follow the surface in some sense include the reaction diffusion textures proposed by Turk [38] and Witkin and Kass [45] Most recently, Turk and Banks [39] described a method for evenly distributing streamlines over a 2D vector field, to represent the flow in a visually ....

Georges Winkenbach and David H. Salesin. Rendering Parametric Surfaces in Pen and Ink, SIGGRAPH 96 Conf. Proceedings, Annual Conference Series, pp. 469-476.

.... style renderings of architectural models in which resolution independent stroke textures were applied to planar surfaces [58] and then later extended this work to apply similarly detailed stroke textures to parametrically defined surfaces, following the direction of the parameterization [59]. They suggest the possibility of using principal directions, in future work, to guide the placement of strokes on nonparametrically defined surfaces. Salisbury et al. created an interactive pen and ink style drawing program in which, among other things, the orientation of the individual elements ....

G. Winkenbach and D.H. Salesin, "Rendering Parametric Surfaces in Pen and Ink," Computer Graphics (Proc. Siggraph `96), pp. 469-476, 1996.

....Reference [20] extended the approach for animation and further refined the use of layers and brush strokes characteristic for creating effective imagery. Both of these efforts were aimed toward creating art, however, and not toward scientific visualization. Along similar lines, references [21, 22, 23] used software to create pen and ink illustrations for artistic purposes. The pen and ink approach has successfully been applied to 2D tensor visualization in [24] In reference [1] painterly concepts as used in our work were presented for visualizing diffusion tensor images of the mouse spinal ....

Georges Winkenbach and David H. Salesin. Rendering parametric surfaces in pen and ink. In Holly Rushmeier, editor, SIGGRAPH 96 Conference Proceedings, Annual Conference Series, pages 469--476. ACM SIGGRAPH, Addison Wesley, August 1996. held in New Orleans, Louisiana, 04-09 August 1996.

....copper plates were the result of a raytracing system by Leister [4] These copper plates can incorporate specular reflection and transparency. However, no special attention was payed to transparency, it was merely something inherited from the raytracing basis of the system. Winkenbach and Salesin [7] presented a rendering system for pen and ink illustrations based on parametric surfaces. Classical rendering techniques are applied to the lines, so shadows, texture, environment and bump mapping result in richer images. Schofield developed Piranesi, a rendering system for non photorealistic ....

G. Winkenbach and D. H. Salesin, "Rendering Parametric Surfaces in Pen and Ink", Computer Graphics (Proc. Siggraph), Vol. 30, pp. 469--476, 1996.

....giving their clients a false impression of completeness. In general, the question of whether to use photorealistic imagery depends on the visual effect intended by the designer. A growing body of research in computer graphics has recognized the power and usefulness of nonphotorealistic imagery [21, 20, 13, 22, 10, 17, 11, 7, 16, 3]. Until now, though, nonphotorealistic rendering (NPR) methods have primarily been batch oriented rather than interactive. An exception is Zeleznik s SKETCH system [22] which makes crude nonphotorealistic renderings using tricks in the standard polygon rendering pipeline) One obstacle to ....

....indicated number of polygons. Our test machine is a 200 MHz Sun Ultra TM 2 Model 2200 with Creator 3D graphics. 6 Our method performs particularly well on smooth meshes, since these have fewer cusps and intersecting silhouette edges than irregular or bumpy surfaces. In contrast, Winkenbach s [21] pen and ink rendering system produces decidedly finer images, but takes several minutes per frame to do so. Over half that time is spent on visibility determination) 5 We thank Paul Haeberli for this rendering method and the source code for implementing it. 6 We use the graphics ....

[Article contains additional citation context not shown here]

G. Winkenbach and D. Salesin. Rendering parametric surfaces in pen and ink. In Proceedings of SIGGRAPH '96, pp. 469--476, August 1996.

....a single image, to control the synthesis procedure. One important application of image analogies that we explore in this paper is the automatic synthesis of various artistic styles from examples. In the past few years, there has been a great deal of work in creating artistic styles by computer [10, 21, 24, 26, 32, 36, 41, 42, 50, 51], a field that has come to be known as non photorealistic rendering (NPR) One drawback of most of these previous works, however, is that the methods have had to be specifically tailored to a specific rendering style (or space of styles) image analogies, by contrast, although they may not be able ....

Georges Winkenbach and David H. Salesin. Rendering Parametric Surfaces in Pen and Ink. In SIGGRAPH 96 Conference Proceedings, pages 469--476, August 1996.

....is that it is currently capable of handling polygonalscenes only. To extend our previewer to handle curved objects, we could either tessellate those objects and use the same BSP tree based shadow volume algorithm, or use a different algorithm, such as the one used by Winkenbach and Salesin [17] since it does not rely on BSP trees. Another possible extension would be to include more types of discontinuity edges in out algorithm. For instance, we could compute soft shadow edges, refracted edges, and edges reflected on curved surfaces. To handle soft shadows we could use an extension of ....

Georges Winkenbach and David H. Salesin. Rendering parametric surfaces in pen and ink. In Proceedings of SIGGRAPH '96 (New Orleans, LA, August 4--9, 1996), pages 469--476, August 1996.

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G. Winkenbach and D.H.Salfi:4U "Rendering Parametric Surfaces in Pen and Ink," Proc. SiggraN 96, ACM Press, 1996, pp. 469-476.

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G. Winkenbach and D. H. Salesin. Rendering parametric surfaces in pen and ink. In Proceedings of SIGGRAPH 96, pages 469--476, Aug. 1996.

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Georges Winkenbach and David H. Salesin. Rendering parametric surfaces in pen-and-ink. In Holly Rushmeier, editor, SIGGRAPH 96 Conference Proceedings, pages 469--476, New Orleans, Louisiana, 1996. 42

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G. Winkenbach and D.H.Salfi:4U "Rendering Parametric Surfaces in Pen and Ink," Proc. SiggraN 96, ACM Press, 1996, pp. 469-476.

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G. Winkenbach and D. H. Salesin. Rendering parametric surfaces in pen and ink. In SIGGRAPH 96 Conference Proceedings, pages 469--476. ACM SIGGRAPH, Addison Wesley, 1996.

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G. Winkenbach and D. H. Salesin. Rendering parametric surfaces in pen and ink. In H. Rushmeier, editor, SIGGRAPH 96 Conference Proceedings, Annual Conference Series, pages 469--476. ACM SIGGRAPH, Addison Wesley, Aug. 1996.

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Georges Winkenbach and David H. Salesin. Rendering parametric surfaces in pen and ink. In Holly Rushmeier, editor, SIGGRAPH 96 Conference Proceedings, Annual Conference Series, pages 469--476. ACM SIGGRAPH, Addison Wesley, August 1996.

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G. Winkenbach and D. Salesin, "Rendering Parametric Surfaces in Pen and Ink," Proc. SIGGRAPH '96, Computer Graphics Proc., Ann. Conf. Series, pp. 469-476, Aug. 1996.

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Georges Winkenbach and David H. Salesin. Rendering parametric surfaces in pen and ink. In Proceedings of SIGGRAPH 96, Computer Graphics Proceedings, Annual Conference Series, pages 469--476, New Orleans, Louisiana, August 1996. ACM SIGGRAPH / Addison Wesley. ISBN 0-201-94800-1.

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G. Winkenbach and D. Salesin. Rendering parametric surfaces in pen and ink. In Proceedings of SIGGRAPH 96, pages 469--476, August 1996.

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G. Winkenbach and D. H. Salesin. Rendering parametric surfaces in pen and ink. In SIGGRAPH 96 Conference Proceedings, pages 469 476. ACM, 1996. The Eurographics Association 2002.

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G. Winkenbach and D. Salesin. Rendering parametric surfaces in pen and ink. In Proceedings of SIGGRAPH 96, pages 469-- 476, August 1996.

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G. Winkenbach and D. H. Salesin, "Rendering Parametric Surfaces in Pen and Ink", Computer Graphics (Proc. Siggraph), Vol. 30, pp. 469--476, 1996.

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G. Winkenbach and D. Salesin. Rendering parametric surfaces in pen and ink. In SIGGRAPH '96 Conference Proceedings, pages 469--476, 1996.

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