Colorization and Illumination of 2D Animations Based on a Region-Tree Representation

（作者）

Nascimento, R. , Queiroz, F. , Rocha, A. , Tsang Ing Ren , Mello, V. , Peixoto, A.

（段落节选）

Colorization and illumination are key processes for creating animated cartoons. Computer assisted methods have been incorporated in animation/illustration systems to reduce the artists effort. This paper presents a new strategy for illumination and colorization of 2D drawings based on a region-tree. Starting from a hand-drawn cartoon, it extracts geometric and topological information and builds a tree structure, ensuring independence among parts of the drawing, such as curves and regions. Based on this structure and its attributes, a colorization method that propagates through consecutive frames of animation is proposed, together with an interpolation method that accurately computes a normal mapping for the illumination process. Different operators on curve and region attributes can be applied independently, obtaining different rendering effects.

The task of painting each cel of an animated sequence has always been a tedious work using traditional methods. In order to simplify and speed up the process, the development of an automatic cel painting system is desired. This paper presents a method for assisting the production of cartoon animation using computers in order to reduce the production expense and to improve the overall quality. It signals a great improvement in the working environment where 2‐D animation is produced. The basic idea of our automatic cel painting mechanism is to extract both statistical and topological features of regions from input animation drawings, and to search for similar corresponding regions in the previous drawing. If the similarity measures are within the accepted thresholds, the corresponding colour will be inherited. A new integrated labelling algorithm constructing statistical region and topological graph features is proposed. Furthermore, a similarity measure of regions is defined and an algorithm of partial matching of attribute graphs is presented. The experimental result shows the feasibility and practicability of the proposed approach.

To address this problem, we have presented aframework of human hair modeling based on grouping hair strands into strips. Each hair strip is modeled by one patch of parametric surface. Polygon tessellation and the alpha-mapping using hair textures are then applied. To continue that work, we present a simple Physics model. In particular, a simple dynamic model is adapted and applied to the control point meshes. A set of dynamics equations are defined and solved. The parametric representation of hair strips can handle deformation of any complexity and still appear smooth. Moreover, because the number of control points is much smaller than that of the tessellated triangle vertices, the computation is fast and achieves real time animation. The animation of hair is controlled using event-triggered procedural animation primitives that implement wind, gravity as well as head movement. Inter hair strip collision avoidance is achieved by introducing springs between any two neighboring hair strips. Collision detection and avoidance of hair with other objects is implemented using ellipsoids and reaction constraints.

In our method, the motion of the granular media is representedby discrete particles as in standard DEM. As illustratedin Figure 1, the mobile particles, including particles inthe flowing layer and particles scattered in space, are maintainedin an active particle list. The immobile particles inthe static layer are reduced and represented by the 2D heightfield columns. For each time step ∆t, our sand simulationmethod contains three main steps. First, the two-layer heightfield model is evolved based on the BCRE equations. Second,the matter transfer between mobile particles and height field columns is modeled through a particle interface, and the elements in the active list are refreshed. Third, the positions and velocities of the mobile particles in the active list are updated with a DEM solver to describe the motion behaviors in

the scene.

To this end, first we construct a high resolution semantic mesh model through automatic global and local registration of a low resolution range data. Such a model is represented using predefined set of control points in a compact fashion, and animated using radial basis functions. In order to recover the 2D positions of the 3D control points in the observed sequence, we use cascade Adaboost-driven search. The search space is reduced through the use of predictive expression modeling. The optimal configuration of the Adaboost responses is determined using combinatorial linear programming which enforces the anthropometric nature of the model. Then the displacement can be reproduced on any version of the model, registered on another face. Our method doesnrsquo;t require dense stereo estimation and can then produce realistic animations, using any 3D model. Promising experimental results demonstrate the potential of our approach.

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基于区域树表示的二维动画的着色与光照

彩色和光照是制作动画片的关键过程。计算机辅助方法已被纳入动画/插图系统，以减少艺术家的努力。本文提出了一种基于区域树的二维图形光照和彩色化的新策略。从手绘动画出发，提取几何信息和拓扑信息，建立树结构，保证了曲线、区域等绘图部分的独立性。基于该结构及其属性，提出了一种在连续动画帧中传播的彩色化方法，并结合一种精确计算光照过程正常映射的插值方法。曲线和区域属性上的不同运算符可以是 独立应用，获得不同的渲染效果 。

使用传统方法绘制动画序列的每个CEL的任务一直是一项乏味的工作。为了简化和加快这一过程，需要开发一个自动化的CEL喷漆系统。本文提出了一种利用计算机辅助动画制作的方法，以降低制作成本，提高整体质量。它标志着二维动画制作工作环境的极大改善。我们的CEL自动绘制机制的基本思想是从输入动画图形中提取区域的统计和拓扑特征，并在前一个图形中搜索相似的对应区域。如果相似性度量在可接受的阈值内，则相应的颜色将被继承。提出了一种构造统计区域和拓扑图特征的综合标记算法。定义了区域的相似性测度，给出了属性图的局部匹配算法。实验结果表明了该方法的可行性和实用性。

为了解决这个问题，我们提出了一种基于将头发束分组成条带的人类头发建模方法。每个发带都由一个参数化曲面片建模。然后应用多边形镶嵌和使用头发纹理的阿尔法映射。为了继续这项工作，我们提出了一个简单的物理模型。特别地，对控制点网格进行了简单的动态建模。定义并求解了一组动力学方程。头发条的参数化表示可以处理任何复杂的变形，并且仍然保持平滑。此外，由于控制点的数目远小于镶嵌三角形顶点的数目，计算速度快，实现了实时动画。头发的动画是使用事件触发的程序动画原语控制的，这些原语实现了风、重力和头部移动。通过在相邻的两个发带之间引入弹簧，可以避免发带间的碰撞。利用椭球体和反应约束实现了头发与其他物体的碰撞检测和避免。

在我们的方法中，颗粒介质的运动被表示为通过离散粒子，如标准DEM。移动粒子，包括流动层和分散在空间中的颗粒保持不变。在活动粒子列表中。不动粒子静态层被缩小并用二维高度表示。字段列。对于每个时间步∆t，我们的砂模拟方法包含三个主要步骤。首先，两层的高度在BCRE方程的基础上发展了场模型。第二，运动粒子与高度之间的物质传递字段列通过粒子接口建模，并且活动列表中的元素将被刷新。第三，职位更新活动列表中的移动粒子的速度使用DEM解算器描述现场。

为此，首先通过对低分辨率范围数据进行全局和局部自动配准，构造了高分辨率语义网格模型。这种模型是用一组预先定义的控制点以紧凑的方式表示的，并使用径向基函数进行动画处理。为了恢复观测序列中三维控制点的二维位置，我们采用级联ADABoost驱动搜索。通过使用预测表达式建模，减少了搜索空间。利用组合线性规划方法确定了ADABoost响应的最优配置，该方法强制实现了模型的人体测量学性质。然后可以在模型的任何版本上复制位移，在另一个面上注册。我们的方法不需要密集的立体估计，然后可以产生现实的动画，使用任何三维模型。有希望的实验结果证明了我们的方法的潜力。

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