Wysiwyg NPR

Kalnins, Robert D.; Markosian, Lee; Meier, Barbara J.; Kowalski, Michael A.; Lee, Joseph C.; Davidson, Philip; Webb, Matthew; Hughes, John F.; Finkelstein, Adam

doi:10.1145/566570.566648

Cited by 81 publications

(8 citation statements)

References 30 publications

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“…DeCarlo et al (2003) described Suggestive Contours, which substantially improved the quality of line renderings, while making deep connections to perception and differential geometry, notably the work of Koenderink (1984). Several systems were created to help artists design artistic rendering styles, such as WYSIWYG NPR (Kalnins et al, 2002) and a procedural NPR system called Freestyle (Grabli et al, 2010). Cole et al (Cole, Golovinskiy, Limpaecher, Barros, Finkelstein, Funkhouser, and Rusinkiewicz (2008); Cole, Sanik, DeCarlo, Finkelstein, Funkhouser, Rusinkiewicz, and Singh (2009)) performed the scientific studies described in Section 1.5 demonstrating that line drawing algorithms were quite good at capturing how artists draw lines.…”

Section: Survey Of Feature Curvesmentioning

confidence: 99%

“…Artistic perturbations of the stroke by analytic (e.g., sine function) or noise functions and offsets (Markosian et al, 1997) can further add high-frequency variations to the stroke. To avoid tiling and stretching artifacts, texture synthesis can be used to generate arbitrary-length stroke textures and offsets (Hertzmann et al, 2002;Kalnins et al, 2002;Bénard et al, 2012;Lang and Alexa, 2015) from examples. Stroke styles can depend on the underlying source geometry, e.g., thicker strokes for nearer objects or less-curved objects (Goodwin et al, 2007), and stroke styles can also vary for different objects and materials.…”

Section: Stroke Renderingmentioning

confidence: 99%

“…More sophisticated texture-based stroke models include "RealBrush", which uses multiple scanned paint strokes to model paint mixing (Lu et al, 2013) and "DecoBrush" (Lu et al, 2014), which uses procedurally-defined line art textures. These stroke textures may also be drawn directly in a WYSIWYG interface (Kalnins et al, 2002;Saito, 2015, 2016). See the video accompanying the work of Kalnins et al (2002) for a particularly inspiring interface.…”

Section: Stroke Renderingmentioning

confidence: 99%

“…These stroke textures may also be drawn directly in a WYSIWYG interface (Kalnins et al, 2002;Saito, 2015, 2016). See the video accompanying the work of Kalnins et al (2002) for a particularly inspiring interface.…”

Section: Stroke Renderingmentioning

confidence: 99%

“…A separate problem is to build artist-friendly tools for authoring artistic styles. There have been various approaches explored in the literature, such as rotoscoping (Kalnins et al, 2002;Sabiston, 2001;Whited et al, 2012;Cardona and Saito, 2015) and procedural authoring (Grabli et al, 2010).…”

Section: Open Research Problemsmentioning

confidence: 99%

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Line Drawings from 3D Models: A Tutorial

Bénard¹,

Hertzmann²

2019

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This tutorial describes the geometry and algorithms for generating line drawings from 3D models, focusing on occluding contours.The geometry of occluding contours on meshes and on smooth surfaces is described in detail, together with algorithms for extracting contours, computing their visibility, and creating stylized renderings and animations. Exact methods and hardware-accelerated fast methods are both described, and the trade-offs between different methods are discussed. The tutorial brings together and organizes material that, at present, is scattered throughout the literature. It also includes some novel explanations, and implementation tips.We believe that these topics ought to be known by anyone interested in understanding the curves in visual representational art. It is one where computer graphics can make a unique contribution. Arguably, the algorithmic simulation of line drawing is a crucial step in understanding visual art. Occluding contoursThis tutorial focuses on the curves known as occluding contours or, simply contours. In some computer graphics research, these have been called silhouettes, though the silhouettes are technically a separate set of curves, as we will describe below.The occluding contours of a simple 3D object are shown in Figure 1.1. As a first definition, suppose we have a 3D object that we wish to render from a specific viewpoint. The occluding contours are surface curves that separate visible parts from invisible parts. By rendering the visible portions of these 3D curves together with the object, we get a basic line drawing (Figure 1.1b).There are many different contour detection and rendering algorithms, and some significant tradeoffs between them. The most important tradeoff is between simple algorithms that produce approximate results, and more complex algorithms that give more precision, control, and stylization capabilities. Just rendering reasonable-looking contours as solid black lines is very straightforward for a graphics programmer. These most basic algorithms can be implemented in a few additional lines of code in an existing renderer, and have been implemented in many real-time applications, including many popular video games (one of the earliest was Jet Set Radio in 2000). However, if we wish to stylize the curves, for example, by rendering the curves with sketchy or calligraphic strokes (Figure 1.1d), things become more difficult. With a bit of perseverance, renderings with distinctive and lovely styles can be created. At times, these renderings may still contain topological artifacts that are not suitable for very high-end production. High-quality algorithms that remove these artifacts are more complex; in the extreme, no provably-correct algorithm exists for this problem. However, there are a number of partial solutions that are good enough to be used in many circumstances, and we discuss in detail the issues involved.Note that, formally, the occluding contour and occluding contour generator are separate curves in 2D and 3D. However, we will frequently use the te...

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Section: Survey Of Feature Curvesmentioning

confidence: 99%

Section: Stroke Renderingmentioning

confidence: 99%

Section: Stroke Renderingmentioning

confidence: 99%

Section: Stroke Renderingmentioning

confidence: 99%

Section: Open Research Problemsmentioning

confidence: 99%

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Line Drawings from 3D Models: A Tutorial

Bénard¹,

Hertzmann²

2019

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A 3D Model Feature-Line Extraction Method Using Mesh Sharpening

Jing

Zhou

2006

Technologies for E-Learning and Digital Entertainment

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Highly Stylised Drawn Animation

Fiore

Reeth

Patterson

et al. 2006

Advances in Computer Graphics

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Abstract. In this paper we argue for our NPAR system as an effective 2D alternative to most of NPR research that is focused on frame coherent stylised rendering of 3D models. Our approach gives a highly stylised look to images without the support of 3D models, and yet they still behave as though animated by drawing, which they are. First, a stylised brush tool is used to freely draw extreme poses of characters. Each character is built up of 2D drawn brush strokes which are manually grouped into layers. Each layer is assigned its place in a drawing hierarchy -Hierarchical Display Model (HDM). Next, multiple HDMs are created for the same character, each corresponding to a specific view. A collection of HDMs essentially reintroduces some correspondence information to the 2D drawings needed for in-betweening and, in effect, eliminates the need for a true 3D model. Once the models are composed, the animation phase can start. The animator first defines keyframes by specifying extreme poses in time. Next, brush stroke trajectories defined by the HDMs of the keyframes are inbetweened automatically across intermediary frames. Finally, each HDM of each generated in-between frame is traversed and all elements are drawn one on another from back to front. Regarding stylisation, we focus on techniques that realise highly rendered styles which are particularly difficult to animate by traditional means including the 'airbrushed', scraperboard, watercolour, Gouache, 'ink-wash', and the 'crayon' style. We believe our system offers a new fresh perspective on computer aided animation production and associated tools.

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Wysiwyg NPR

Cited by 81 publications

References 30 publications

Line Drawings from 3D Models: A Tutorial

Line Drawings from 3D Models: A Tutorial

A 3D Model Feature-Line Extraction Method Using Mesh Sharpening

Highly Stylised Drawn Animation

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