Shadow metamorphosis

Any two objects A and B can be viewed as two different projections of their Cartesian product A×B. Rotating and projecting A×B results in a continuous transformation of A into B. During certain rotations, the contour of the Cartesian product remains the same although its projection changes. Based on these properties, we derive a fast and simple morphing algorithm without topological constraints on either object.     

Processor reconfiguration through instruction-set metamorphosis

The processor reconfiguration through instruction-set metamorphosis (PRISM) general-purpose architecture, which speeds up computationally intensive tasks by augmenting the core processor's functionality with new operations, is described. The PRISM approach adapts the configuration and fundamental operations of a core processing system to the computationally intensive portions of a targeted application. PRISM-1, an initial prototype system, is described, and experimental results that demonstrate the benefits of the PRISM concept are presented     

DMorph [image metamorphosis]

Image morphing is an artist-driven process. A creative human being looks at the images (or sequences) to be bridged and determines a way to make the changes that will be pleasing to the viewer and harmonious with the piece. To help these artists, I've developed a technique for automatically and smoothly turning one convex 3D shape into another. Like any automatic morph method, this technique should be viewed as a tool and not a self-guided process. DMorph has pros and cons. On the pro side, it is satisfyingly simple and robust and easy to program. It doesn't place any constraints on the two objects being interpolated except that they're convex. One object can be a 200-sided cone where 200 polygons all share a single vertex, and the other object a baseball, and the algorithm doesn't care. There's no feature matching, automatic or otherwise. The transformations are smooth, and the blending looks nice. On the con side, the program is limited to convex objects.     

Image metamorphosis with scattered feature constraints

This paper describes an image metamorphosis technique to handle scattered feature constraints specified with points, polylines, and splines. Solutions to the following three problems are presented: feature specification, warp generation, and transition control. We demonstrate the use of snakes to reduce the burden of feature specification. Next, we propose the use of multilevel free-form deformations (MFFD) to compute C²-continuous and one-to-one mapping functions among the specified features. The resulting technique, based on B-spline approximation, is simpler and faster than previous warp generation methods. Furthermore, it produces smooth image transformations without undesirable ripples and foldovers. Finally, we simplify the MFFD algorithm to derive transition functions to control geometry and color blending. Implementation details are furnished and comparisons among various metamorphosis techniques are presented     

非结构网格下曲线变形的水平集方法

采用基于非结构网格的水平集方法对曲线变形问题进行了数值模拟。通过度量函数最优化过程得到曲线变形的驱动方程,驱动方程中增加曲线曲率项对度量函数进行优化,空间上采用有限体积法求解水平集方程,时间上采用Runge-kutta显式方法,时间、空间均达到2阶精度。实验结果得到了高质量的过渡曲线,显示复杂几何拓扑形变可以理想地实现。     

彩色图像渐变的插值方法

针对目前图像渐变算法只考虑两个彩色图像之间的渐变并且没有考虑三个颜色分量内在相关性的问题,在二元混合向量有理插值的基础上,提出了一种非线性的多幅彩色图像渐变的新方法。首先将多幅图像中每个像素的RGB三原色看做是平面域上的向量,利用二元Newton-Thiele型向量连分式建立有理插值曲面,再对此插值曲面进行重采样,得到一系列的渐变中间图像。实验结果表明,该算法在保持图像特征和过渡图像的可视性方面均优于其他算法。     

Skeleton-guided 3D shape distance field metamorphosis

We introduce an automatic 3D shape morphing method without the need of manually placing anchor correspondence points. Given a source and a target shape, we extract their skeletons and automatically estimate the meaningful anchor points based on their skeleton node correspondences. Based on the anchors, dense correspondences between the interior of source and target shape can be established using earth mover’s distance (EMD) optimization. Skeleton node correspondence, estimated with a voting-based method, leads to part correspondence which can be used to confine the dense correspondence within matched part pairs. This produces smooth and plausible morphing sequence based on distance field interpolation (DFI). We demonstrate the effectiveness of our algorithm over shapes with large geometric variation and structural difference.     

Volume-based three-dimensional metamorphosis using sphere-guided region correspondence

surface metamorphosis extends this paradigm by interpolating between discrete volume representations of the surfaces. The insensitivity of the established techniques to the surface topology enables morphing between completely different surfaces: however it can also lead to intermediate surfaces which have different topology from the originals. We present a method which improves on this situation by ensuring that no part of each surface remains disconnected during the morph. The morph is guided by region correspondence, derived automatically from a sphere representation of each surface: this can be combined with manual correspondence to retain user control over the morph. What emerges is a fast and flexible method for morphing surfaces, as demonstrated on several examples. Published online: 19 July 2001     

Self-intersection elimination in metamorphosis of two-dimensional curves

H :[0, 1]× ³→ ³, where H(t, r) for t=0 and t=1 are two given planar curves C ₁(r) and C ₂(r). The first t parameter defines the time of fixing the intermediate metamorphosis curve. The locus of H(t, r) coincides with the ruled surface between C ₁(r) and C ₂(r), but each isoparametric curve of H(t, r) is self-intersection free. The second algorithm suits morphing operations of planar curves. First, it constructs the best correspondence of the relative parameterizations of the initial and final curves. Then it eliminates the remaining self-intersections and flips back the domains that self-intersect.     

Robust image metamorphosis immune from ghost and blur

In this paper, we propose a novel method for the metamorphosis between two different images. By the approach, the transition sequence is generated by stitching two forward and backward warped sequences in a three-dimensional space along transition surface. In contrast to the traditional methods by blending two warped images at each intermediate frame, we continuously warp images on opposite direction without blending until the two warped images match in a three-dimensional space leading to a better transition in quality. Furthermore, for each pixel, we make decision of choosing a given input image best suitable so as to produce plausible in-between images to prevent from ghost and blur. By our scheme, the transition surface is computed by minimizing an energy function in terms of graph-cut optimization. Depending on the transition surface, a warp function is proposed to create a smooth and clear transformation. We demonstrate the advantage of our framework by performing transformation test to various kinds of image couples.     

基于混合有理插值的图像渐变算法*

针对现有的图像渐变方法只考虑两个图像间渐变的情况,提出一种非线性的多幅图像间渐变的新方法,即一元混合有理插值方法。将多幅图像间相同位置的像素点建立对应关系,按照该关系建立一元混合有理插值函数,对插值函数进行重采样,得到一系列的渐变中间图像。实验表明,新算法在反映空间数据的分布特性、保证图像纹理特征方面均优于其他算法,具有计算精度高、适应性强、易于编程实现等优点,是一种较实用的算法。     

A level-set approach for the metamorphosis of solid models

We present a new approach to 3D shape metamorphosis. We express the interpolation of two shapes as a process where one shape deforms to maximize its similarity with another shape. The process incrementally optimizes an objective function while deforming an implicit surface model. We represent the deformable surface as a level set (iso-surface) of a densely sampled scalar function of three dimensions. Such level-set models have been shown to mimic conventional parametric deformable surface models by encoding surface movements as changes in the grayscale values of a volume data set. Thus, a well-founded mathematical structure leads to a set of procedures that describes how voxel values can be manipulated to create deformations that are represented as a sequence of volumes. The result is a 3D morphing method that offers several advantages over previous methods, including minimal need for user input, no model parameterization, flexible topology, and subvoxel accuracy     

Detection and classification of topological evolution for linear metamorphosis

The advantage of functional methods for shape metamorphosis is the automatic generation of intermediate shapes possible between the key shapes of different topology types. However, functional methods have a serious problem: shape interpolation is applied without topological information and thereby the time values of topological changes are not known. Thus, it is difficult to identify the time intervals for key frames of shape metamorphosis animation that faithfully visualize the topological evolution. Moreover, information on the types of topological changes is missing. To overcome the problem, we apply topological analysis to functional linear shape metamorphosis and classify the type of topological evolution by using a Hessian matrix. Our method is based on Morse theory and analyzes how the critical points appear. We classify the detected critical points into maximum point, minimum point, and saddle point types. Using the types of critical points, we can define the topological information for shape metamorphosis. We illustrate these methods using shape metamorphosis in 2D and 3D spaces.     

3D shape metamorphosis based on T-spline level sets

We propose a new method for 3D shape metamorphosis, where the in-between objects are constructed by using T-spline scalar functions. The use of T-spline level sets offers several advantages: First, it is convenient to handle complex topology changes without the need of model parameterization. Second, the constructed objects are smooth (C² in our case). Third, high quality meshes can be easily obtained by using the marching triangulation method. Fourth, the distribution of the degrees of freedom can be adapted to the geometry of the object. Given one source object and one target object, we firstly find a global coordinate transformation to approximately align the two objects. The T-spline control grid is adaptively generated according to the geometry of the aligned objects, and the initial T-spline level set is found by approximating the signed distance function of the source object. Then we use an evolution process, which is governed by a combination of the signed distance function of the target object and a curvature-dependent speed function, to deform the T-spline level set until it converges to the target shape. Additional intermediate objects are inserted at the beginning/end of the sequence of generated T-spline level sets, by gradually projecting the source/target object to the initial/final T-spline level set. A fully automatic algorithm is developed for the above procedures. Experimental results are presented to demonstrate the effectiveness of our method.     

Bilinear interpolation for facial expression and metamorphosis in real-time animation

This paper describes a new method for generating facial animation in which facial expression and shape can be changed simultaneously in real time. A 2D parameter space independent of facial shape is defined, on which facial expressions are superimposed so that the expressions can be applied to various facial shapes. A facial model is transformed by a bilinear interpolation, which enables a rapid change in facial expression with metamorphosis. The practical efficiency of this method has been demonstrated by a real-time animation system based on this method in live theater.     

智能网卡综述

以可编程交换机和智能网卡为代表的可编程网络设备在数据中心被越来越广泛地应用,它们支持在网络数据传输路径上执行自定义的数据处理逻辑,这为构建高性能的在网存储系统带来了新的机遇. 然而,可编程网络设备的硬件资源限制较多,如何充分发挥它们的优势、最大限度地加速存储系统仍面临着诸多挑战. 系统地综述了在网存储系统的研究进展,首先介绍了可编程网络设备的硬件结构与性能特征,并基于此总结了构建高性能在网存储系统面临的两大挑战：软硬件分工以及系统容错. 然后根据可编程网络设备执行的任务（缓存、协调、调度、聚合）对现有的在网存储系统进行分类和阐述,并以多个在网存储系统为实例分析对应的设计难点以及软件技术. 最后指明了在网存储系统进一步研究中需要着重探索的问题,包括交换机与网卡的协同、安全、多租户以及自动卸载.

     

Fast and intuitive metamorphosis of 3D polyhedral models using SMCC mesh merging scheme

A very fast and intuitive approach to generate the metamorphosis of two genus 0 3D polyhedral models is presented. There are two levels of correspondence specified by animators to control morphs. The higher level requires the animators to specify scatter features to decompose the input models into several corresponding patches. The lower level optionally allows the animators to specify extra features on each corresponding patch for finer correspondence control. Once these two levels of correspondence are established, the proposed schemes automatically and efficiently establish a complete one-to-one correspondence between two models. We propose a novel technique called SMCC (Structures of Minimal Contour Coverage) to efficiently and robustly merge corresponding embeddings. The SMCC scheme can compute merging in linear time. The performance of the proposed methods is comparable to or better than state-of-the-art 3D polyhedral metamorphosis. We demonstrate several examples of aesthetically pleasing morphs, which can be created very quickly and intuitively.