【译文】

Adam Finkelstein and Lee Markosian
Princeton University Department of Computer Science

普林斯顿大学计算机科学系

Project funded by Intel Research Labs (AIM program)

由英特尔研究实验室资助（AIM项目）

  • 摘要

      三维计算机图形建模是一个艰苦的的任务，通常由那些资深的专家担任。相比之下，对许多人来说绘画来的更容易些。3D建模一个困难的原因之一是，现有的工具权衡易于使用非常精确的控制（这往往是不可取的）。在实践中，艺术家和插图画家几乎总是选择一些风格化的程度（Non-photorealism）间接地唤起了现场的复杂性。 其结果可以比文字表示要简单得多，而且也更有表现力。目前计算机图形设计没有这样的选项 -不存在任何工具的模型被应用到它的几何形状和独特的外观中。

我们正在开发用来进行程式化内容创作的工具，通过接口轻松画出自由的形状，然后直接用手工绘制的笔画标注这些形状，类似于铅笔，圆珠笔，蜡笔，或其他媒介。 由此产生的3D场景看起来很像一个绘图，尤其因为它可以活动地或交互地查看。这一技术的应用，包括技术插图，建筑，教育，虚拟现实，动画，广告，和游戏 – 这些都是动态图像，是用讲来故事，沟通，解释，或告知的内容。

  • 研究目标

在这项工作中，我们对于三维计算机图形应用来解决内容创作。尽管计算机图形技术的突飞猛进，对现实场景的描绘伟成为可能。尽管对于问题的建模，动画和渲染都有了大量的研究，尽管有许多的软件产品来专门创建3D内容，但从头开始创建新的场景丰富的问题​​，特别是对非专业人士来说，形式依然严峻。

要使产生的图像必须逼真而产生新的3D内容的问题是特别困难的。我们主要关注的是更少的投入，技术插图，能描绘出复杂的、有机的场景。插图画家插图画家插图画家

能唤起精心程式化的笔触相对较少的复杂性。虽然艺术家已经实行这一原则有一个世纪了，它已经在很大程度上忽视了三维计算机图形。目前的建模工具，已经为程式化的3D场景与手绘动画的视觉品质创建提供了许多选项。

除了简化了设计师所需的输入，创建程式化的场景还有很多方面的优势。 例如，为了集中观众对重要的特点的注意力，而忽视无关细节，便插图使用程式化的图像。 建筑师往往喜欢图纸以描述一个场景或记录未完成的工作。由于程式化的渲染往往更容易理解，它们被广泛用于包括医学插图在“华尔街日报”的画像的背景下。 最后，针对儿童的书籍，游戏和电影的流行性证明程式化的图像可以更吸引人。

最近的一个研究描述了在计算机图形学中非真实感渲染（NPR）带来的插图原则。 为了调查NPR，看了ooch 、Gooch、Strothotte 和 Schlechtweg的书，克雷格雷诺兹的网站。.在这方面的努力主要集中在渲染算法。 然而，很少有工具已经开发出这些算法提供给设计师。

我们的假设是， 让设计人员通过一个图形界面的算法直接进入NPR，能够使复杂的、有机的场景变得更方便，比传统的建模工具更加快捷，在自然景观建设中我们打算通过构建基于这些系统来验证假说，并展示其效用。我们的目标是把测试在各种用户的手中 - 初学者和专家，艺术家和非艺术家手中的原型。请观看此页面下载软件的链接。

  • Progress进展

Prior to undertaking this project at Princeton we have tackled many related research problems in NPR (see our research pages at here and here ).在普林斯顿大学进行这个项目之前，我们已经解决了在NPR的问题上的许多相关的研究。 Indeed it was these previous efforts that led to the inception of this project.事实上，这是以前的成果，由于这些的存在才有了这个项目开始的。 Since undertaking this project in Autumn 2001 we have written three papers specifically tied to the objectives described here:自从在2001年秋季开始进行了这个项目，我们已经写了三篇论文，类似于这里所描述的目标：

【原文】

    3D Content Creation Made Easy
    Through Non-Photorealism

    Adam Finkelstein and Lee Markosian
    Princeton University Department of Computer Science

    Project funded by Intel Research Labs (AIM program)

    Summary

    Modeling for 3D computer graphics is a painstaking task that is typically relegated to trained experts. In contrast, drawing is easy for many people. One reason for the difficulty of 3D modeling is that existing tools trade off ease of use for very precise control (which is often undesirable). A second reason stems from the emphasis in computer graphics on photorealism. When the subject matter is a natural scene, realism demands a vast amount of detail. In practice, artists and illustrators nearly always choose some degree of stylization (non-photorealism) to evoke the complexity of the scene indirectly. The result can be much simpler than a literal representation, yet also more expressive. Currently no such option is available to computer graphics designers – no tools exist to model both a geometric shape and the stylized look to be applied to it.

    We are developing tools for stylized content creation, via interfaces for (1) easily sketching general free-form shapes, and then (2) directly annotating those shapes with hand-drawn strokes resembling pencil, pen, pastel, or other media. The resulting 3D scene will look much like a drawing, even as it is animated or viewed interactively. Applications of this technology include technical illustration, architecture, education, virtual reality, animation, advertising, and games – any context in which dynamic imagery is used to tell stories, communicate, explain, or inform.

    Research Objectives

    In this work we address the problem of content creation for 3D computer graphics applications. Despite rapid advances in computer graphics technology that now make possible the depiction of scenes of great realism and detail, the problem of creating rich new scenes from scratch remains challenging, especially for non-professionals. This is true despite much research into problems of modeling, animation and rendering, and despite many software products specializing in creating 3D content.

    The problem of generating new 3D content is especially difficult when the resulting imagery must be photorealistic. Our key observation is that with techniques of illustration, much less input may be required, even to depict complex, organic scenes. The illustrator can evoke complexity with relatively few carefully stylized strokes. While artists have applied this principle for centuries, it has been largely overlooked in 3D computer graphics. Current modeling tools do not offer many options for creating stylized 3D scenes with the visual qualities of hand-drawn animations.

    In addition to simplifying the input required of a designer, there are a number of other advantages to creating stylized scenes. For example, illustrators use stylized imagery in order to focus the viewer’s attention on important features while downplaying extraneous details. Architects often prefer drawings in order to imbue a scene with a specific mood or to convey a quality of unfinishedness. Because stylized renderings are often easier to understand, they are used in contexts ranging from medical illustrations to portraits in the Wall Street Journal. Finally, stylized imagery can be more engaging, as evidenced by its prevalence in books, games, and movies targeted for children.

    A recent branch of research generally described as non-photorealistic rendering (NPR) brings principles of illustration to bear in computer graphics. For an survey of NPR methods see the books by Gooch and Gooch and Strothotte and Schlechtweg or this web page by Craig Reynolds. The bulk of the effort in this area has focused on rendering algorithms. However, few tools have been developed to make these algorithms available to designers.

    Our hypothesis is that giving designers direct access to NPR algorithms through a drawing interface will empower them to make complex, organic scenes more easily and quickly than can be done with conventional modeling tools. We intend to verify the hypothesis by constructing a system based on these principles and demonstrating its utility in constructing natural scenes. Our goal is to put test our prototypes in the hands of a variety of users – both novices and experts, both artists and non-artists. Please watch this page for links to downloadable software.

    Progress

    Prior to undertaking this project at Princeton we have tackled many related research problems in NPR (see our research pages at here and here). Indeed it was these previous efforts that led to the inception of this project. Since undertaking this project in Autumn 2001 we have written three papers specifically tied to the objectives described here:

    Software downloads
    • Our prototype software called JOT implements much of the functionality described in these papers and is available here.