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标题: 给3D动画软件添加一个3D打印功能 [打印本页]

作者: 铁锹 时间: 2012-8-1 14:50
标题: 给3D动画软件添加一个3D打印功能
原文摘录如下：

Watch out, Barbie: omnivorous beasts are assembling in a 3D printer near you.

A group of graphics experts led by computer scientists at Harvard have created an add-on software tool that translates video game characters—or any other three-dimensional animations—into fully articulated action figures, with the help of a 3D printer.
The project is described in detail in the Association for Computing Machinery (ACM) Transactions on Graphics and will be presented at the ACM SIGGRAPH conference on August 7.
Besides its obvious consumer appeal, the tool constitutes a remarkable piece of code and an unusual conceptual exploration of the virtual and physical worlds.

"In animation you're not necessarily trying to model the physical world perfectly; the model only has to be good enough to convince your eye," explains lead author Moritz Bächer, a graduate student in computer science at SEAS. "In a virtual world, you have all this freedom that you don't have in the physical world. You can make a character so anatomically skewed that it would never be able to stand up in real life, and you can make deformations that aren't physically possible. You could even have a head that isn't attached to its body, or legs that occasionally intersect each other instead of colliding."
Returning a virtual character to the physical world therefore turns the traditional animation process on its head, in a sort of reverse rendering, as the image that's on the screen must be adapted to accommodate real-world constraints.
Bächer and his coauthors demonstrated their new method using characters from Spore, an evolution-simulation video game. Spore allows players to create a vast range of creatures with numerous limbs, eyes, and body segments in almost any configuration, using a technique called procedural animation to quickly and automatically animate whatever body plan it receives.
As with most types of computer animation, the characters themselves are just "skins"—meshes of polygons—that are manipulated like marionettes by an invisible skeleton.
"As an animator, you can move the skeletons and create weight relationships with the surface points," says Bächer, "but the skeletons inside are non-physical with zero-dimensional joints; they're not useful to our fabrication process at all. In fact, the skeleton frequently pro***des outside the body entirely."
Bächer tackled the fabrication problem with his Ph.D. adviser, Hanspeter Pfister, Gordon McKay Professor of Computer Science at SEAS. They were joined by Bernd Bickel and Doug James at the Technische Universität Berlin and Cornell University, respectively.
This team of computer graphics experts developed a software tool that achieves two things: it identifies the ideal locations for the action figure's joints, based on the character's virtual articulation behavior, and then it optimizes the size and location of those joints for the physical world. For instance, a spindly arm might be too thin to hold a robust joint, and the joints in a curving spine might collide with each other if they are too close.
The software uses a series of optimization techniques to generate the best possible model, incorporating both hinges and ball-and-socket joints. It also builds some friction into these surfaces so that the printed figure will be able to hold its poses.
The tool also perfects the model's skin texture. Procedurally animated characters tend to have a very roughly defined, low-resolution skin to enable rendering in real time. Details and textures are typically added through a type of virtual optical illusion: manipulating the normals that determine how light reflects off the surface. In order to have these details show up in the 3D print, the software analyzes that map of normals and translates it into a realistic surface texture.
Then the 3D printer sets to work, and out comes a fully assembled, robust, articulated action figure, bringing the virtual world to life.
"With an animation, you always have to view it on a two-dimensional screen, but this allows you to just print it and take an actual look at it in 3D," says Bächer. "I think that’s helpful to the artists and animators, to see how it actually feels in reality and get some feedback. Right now, perhaps they can print a static scene, just a character in one stance, but they can’t see how it really moves. If you print one of these articulated figures, you can experiment with different stances and movements in a natural way, as with an artist’s mannequin."
Bächer's model does not allow deformations beyond the joints, so squishy, stretchable bodies are not yet captured in this process. But that type of printed character might be possible by incorporating other existing techniques.
For instance, in 2010, Pfister, Bächer, and Bickel were part of a group of researchers who replicated an entire flip-flop sandal using a multi-material 3D printer. The printed sandal mimicked the elasticity of the original foam***bber and cloth. With some more development, a later iteration of the "3D-print button" could include this capability.
"

erhaps in the future someone will invent a 3D printer that prints the body and the electronics in one piece," Bächer muses. "Then you could create the complete animated character at the push of a button and have it***n around on your desk."
Harvard’s Office of Technology Development has filed a patent application and is working with the Pfister Lab to commercialize the new technology by licensing it to an existing company or by forming a start-up. Their near-term areas of interest include cloud-based services for creating highly customized, user-generated products, such as toys, and enhancing existing animation and 3D printer software with these capabilities.
The research was supported by the National Science Foundation, Pixar, and the John Simon Guggenheim Memorial Foundation.

在线翻译——“本人尝试翻译了前面几段，好吃力啊，有没有牛人啊，帮忙更好地翻译一下。“

当心，芭比娃娃：在您附近的三维打印机正在组装杂食性野兽。

一个有计算机科技学家领导的图形学专家团队在哈佛大学创建，他们致力于为动画软件研发3D打印的附加功能，用来转换视频游戏中的人物角色或任何其他三维动画，有利于借助3D打印机阐明角色的动作。

该项目已经在ACM进行了转译图形学上的详细描述和论证，并将于8月7日的ACM SIGGRAPH2012会议提出。

消费者之所以对其有这么明显的吸引力，是因为工具构成上有着一系列非凡的代码，以及开发者们在虚拟和物理世界的进行了不寻常的概念探索。

“在动画中，你不一定要把模型处理的很完美，它的是否足够好，只有由你的眼睛说了算，”主创作者——SEAS的计算机科学研究生莫里茨巴切尔解释说，“在虚拟世界中，你拥有了在物理世界所没有的自由。你可以使使字符截面倾斜，但它永远也无法站立在现实生活中，你可以尝试身体的任意变形，而现实却没有这种可能，你甚至可以让头部或者腿与身体若即若离。”

回到一个虚拟人物的物理世界，因此将其头部的传统动画制作过程，在一种反向渲染，在屏幕上的形象，必须调整以适应现实世界的约束。

巴切尔和他的合作者展示他们的新方法，从孢子，一种进化模拟视频游戏中使用的字符。孢子允许玩家创造的生物种类繁多，无数的四肢，眼睛和身体部分几乎在任何配置，使用的技术称为程序动画，快速，自动动画它接收任何身体的计划。

与大多数类型的计算机动画，文字本身只是“皮肤”的多边形，是一种无形的骨架像木偶一样操纵网格。

巴切尔，说：“作为一个动画，你可以移动的骨骼和创造与面点的重量关系，”但里面的骨骼与关节零维非物质，它们不是有助于我们在所有的制造过程。事实上，骨骼经常伸出完全以外的身体。“

巴切尔解决制造问题与他的博士顾问Hanspeter普菲斯特，戈登麦凯计算机科学系教授于海。他们也加入了由Bernd Bickel和道格·詹姆斯，分别在柏林工业大学和康奈尔大学。

这支球队的计算机图形专家研制1软件工具，实现了两件事情：它确定的行动图的关节的理想地点，基于字符的虚拟衔接的行为，并然后它优化的大小和物理世界的这些关节的位置。例如，一个细长的手臂可能太薄，保持一个强大的联合，并在弯曲的脊柱关节可能互相碰撞，如果他们太接近。

该软件采用了一系列优化技术，以产生最好的模型，结合了铰链，球和插座接头。它还建立了一些摩擦，到这些表面，使印刷的数字将是能够保持其构成。

该工具还完善模型的皮肤纹理。程序动画人物往往有一个非常粗略的定义，低分辨率的皮肤，使实时渲染。通常添加细节和纹理通过虚拟错觉：操纵光线反射表面的法线决定。为了有这些细节显示在3D打印，软件分析，法线图，并转化为现实的表面纹理。

然后，三维打印机的设置工作，并走出来完全组装，健壮，铰接式行动图，使虚拟世界的生活。

巴切尔说：“动画，你总是有一个二维的屏幕上查看它，但是这允许您只需打印出来，并采取实际看它在3D。”

“我认为是有帮助的艺术家和动画，看它是如何在现实中的感觉，并得到一些反馈。眼下，他们也许可以打印一个静态的场景，只是一个字符在一个立场，但他们不能看到它如何真正的行动。如果您打印这些铰接式数字之一，你可以尝试不同的立场，以自然的方式运动与艺术家的模特。“

巴切尔的模型不允许超出了关节变形，不那么湿软，伸缩机构尚未在这一过程中捕获。但打印的字符的类型有可能通过整合现有的其他技术。

普菲斯特，巴切尔，Bickel例如，在2010年，是一组研究人员谁复制整个触发器凉鞋用多材料三维打印机的一部分。印刷凉鞋模仿原来的泡沫橡胶和布的弹性。多一些发展的“三维”打印“按钮，”以后的迭代可能包括此功能。

“也许将在未来有人发明了一种3D打印机打印在一块，身体和电子”巴切尔缪斯女神。 “那么，你可以创建一个按钮完整的动画人物，它运行你的办公桌上。”

哈佛大学的科技发展办公室已经提交了专利申请，并正在与普菲斯特实验室工作的商业化许可给现有的公司或新技术，形成了一个立项启动。他们近期感兴趣的领域包括基于云的服务，为创建高度定制的，用户生成的产品，如玩具，这些能力的加强与现有的动画和三维打印机软件。

这项研究是由美国国家科学基金会，皮克斯和约翰·西蒙·古根海姆纪念基金会提供支持。Web3D纳金网www.narkii.com

作者: 艾朵儿 时间: 2012-8-3 17:57
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