Automatic and interactive evolution of vector graphics images with genetic algorithms

Vector graphics are popular in illustration and graphic design. Images are composed of discrete geometric shapes, such as circles, squares, and lines. The generation of vector images by evolutionary computation techniques, however, has been given little attention. JNetic is an implementation of a comprehensive evolutionary vector graphics tool. Vector primitives available range from simple geometric shapes (circles, polygons) to spline-based paint strokes. JNetic supports automatic and user-guided evolution, chromosome editing, and high-detail masks. Automatic evolution involves measuring the pixel-by-pixel colour distance between a candidate and target image. Masks can be painted over areas of the target image, which help reproduce the high-detail features within those areas. By creative selection of primitives and colour schemes, stylized interpretations of target images are produced. The system has been successfully used by the authors as a creative tool.     

矢量图形的艺术特征

探讨了矢量图形的艺术特征;通过对矢量图形绘图软件强大的制作与处理功能的介绍,梳理出矢量图形线条、色调、造型、审美情趣、传统技法的传承与发展等方面表现形式;矢量图形具有线条简单洗练、色调轻松明快、造型逼真夸张、唯美的艺术情趣、平面化的造型等诸多艺术特征,给人以强烈的视觉冲击;矢量图形以其强大的技术功能,大量运用于时尚、卡...     

Visualizing business data with generalized treemaps

Business data is often presented using simple business graphics. These familiar visualizations are effective for providing overviews, but fall short for the presentation of large amounts of detailed information. Treemaps can provide such detail, but are often not easy to understand. We present how standard treemap algorithms can be adapted such that the results mimic familiar business graphics. Specifically, we present the use of different layout algorithms per level, a number of variations of the squarified algorithm, the use of variable borders, and the use of non-rectangular shapes. The combined use of these leads to histograms, pie charts and a variety of other styles     

A method to improve two-dimensional layout

A graphics problem of great interest to industry is that of optimum two-dimensional layout. An operator is given a number of rectangular sheets and an order for a specified number of certain types of two-dimensional shapes. The objective is to cut the shapes out of the sheets in such a way as to minimize the amount of waste produced. A system is proposed where a tentative solution is automatically generated and then interactive improvements are allowed by a conversational display unit. The design criteria, the structure and the main features of the system are illustrated.     

谈谈图学教材

讨论大图学下的教学理念与方法及大图学学科系列教材的配套建设问题。从学科 分类、图学的科学基础、计算基础、图学实践、图学应用等各个角度讨论了图学的理论教学与 实践教学,以及各学科间的相互关系。基于形是图之源,图是形的载体的认识基础,给出了工 程图学、画法几何、计算机图形学、计算机图像学等主要教材的一些编写原则。基于图学的根 本是几何,建议专门编写一本《图学计算基础》作为图学的公共教材。     

Implicit Fitting Using Radial Basis Functions with Ellipsoid Constraint

Implicit planar curve and surface fitting to a set of scattered points plays an important role in solving a wide variety of problems occurring in computer graphics modelling, computer graphics animation, and computer assisted surgery. The fitted implicit surfaces can be either algebraic or non‐algebraic. The main problem with most algebraic surface fitting algorithms is that the surface fitted to a given data set is often unbounded, multiple sheeted, and disconnected when a high degree polynomial is used, whereas a low degree polynomial is too simple to represent general shapes. Recently, there has been increasing interest in non‐algebraic implicit surface fitting. In these techniques, one popular way of representing an implicit surface has been the use of radial basis functions. This type of implicit surface can represent various shapes to a high level of accuracy. In this paper, we present an implicit surface fitting algorithm using radial basis functions with an ellipsoid constraint. This method does not need to build interior and exterior layers for the given data set or to use information on surface normal but still can fit the data accurately. Furthermore, the fitted shape can still capture the main features of the object when the data sets are extremely sparse. The algorithm involves solving a simple general eigen‐system and a computation of the inverse or psedo‐inverse of a matrix, which is straightforward to implement.     

Images of the rose

The surprisingly simple rose equation can provide a fertile basis for generating many visually intriguing 3D forms. This equation was originally investigated in 2D in the 18th century. However, today, using modern computer graphics techniques, full 3D versions can be visualized. The geometrical surfaces of the rose functions correspond to the zeros of the equations and are visualized as the isosurfaces of 3D fields. Despite their apparent complexity, the surfaces are not generated by iteration nor by the intersection of primitives, and it is encouraging that such simple functions can produce a wealth of interesting geometrical shapes. Solid textures and colour maps are designed using equations in a simular way. These can be used to further enhance the aesthetic sense and visual appearance of the geometrical forms.     

Using Marching Cubes on Small Machines

A simple technique to visualize the isosurfaces extracted from a cell-based volumetric dataset using the Marching Cubes algorithm is proposed. The technique exploits the intrinsic ordering of the triangles produced by the surface extraction algorithm by adopting a Back-to-Front visualization technique. The use of the technique together with the adoption of a simple shading algorithm permits the rendering of high resolution volumetric datasets in computational environments with limited capabilities in terms of memory and graphics hardware.     

Projection Theory and Research of Ancient Chinese Graphics

Demonstrating the approach to protract the figure of three-dimensional graphs with geometrical forms in two-dimensional planes, graphics is a basic technical discipline of examining protracting engineering drawings using the method of projection and addressing issues on space geometry as well as its theory and approach. Graphics is also a kind of semiotic system of writing. China boasts of rich tradition of graphics with amazing architectural drawings in Pre-Qin period, booming theories of graphics in Wei and Jin Dynasties, refined protracted drawings in Song and Yuan Dynasties, and graphics being regarded as important instruments in Ming and Qing Dynasties when thorough apprehension were pursued in order to seek the practice of administration. It not only forms the basis for modern and contemporary graphics in China, but also shapes the future development of graphics.     

中国图学投影理论及其研究

图学论证了在二维平面上绘制三维空间几何形状的图形的方法,是研究 投影法绘制工程图样和解决空间几何问题、理论及方法的技术基础学科。中国是一个具有丰 富图学传统的国家。中国图学的投影理论及其研究在先秦之前已有见端倪,魏晋时期已提出 焦点透视的图学理论,宋元之际,图样绘制之精,投影画法的创新,使图学理论大具。中国 图学的投影理论不仅为中国古代科技的发展提供了信息支撑,也为近代中国图学迅速走向近 现代奠定了理论基础。     

草图理解技术研究进展

本文概述了草图理解技术(包括草图识别和语义理解)的现状。首先，草图识别包括预处理和图形识别．根据各种图形处理机制，介绍了四种图形识别方法：基于笔划的、基于图元的、基于几何特征的、基于组合图形的。其次．深入分析了几个语义理解方法，一般包括三个环节：语义获取关系分析和高层应用。最后，本文提出了几何模型、用户模型和领域模型。讨论了草图理解中的主要问题并给出初步解决方案。     

Monge mapping using hierarchical NURBS

Texture mapping is an efficient and effective tool in computer graphics and animation. While computationally very cost-effective, texture mapping may produce non-realistic appearances of shapes in 3D environment, especially when viewing closely. To improve the realism of 3D modeling, bump mapping technique is developed to add details with the 3D models on top of texture mapping. Bump mapping, however, offers only simple and visual enhancement. Displacement mapping technique can further improve the localized detail of geometry. In this paper, Monge mapping technique is developed for detail and local shape modification of NURBS represented geometry in a 3D environment. Based on multiresolution and refinement schemes, Hierarchical NURBS (H-NURBS) is first investigated to design a mechanism for the purpose of carrying localized geometric information. Monge mapping on H-NURBS patch can be easily performed via simple cut-and-paste operation. Parametric control of the local shapes is developed to facilitate easier and better 3D local modeling.     

Graphic representations of three-component vector fields

A technique is described for graphically displaying three-component vector fields in a display plane. Direction of the vector field is indicated by displaying, at various points of the plane, sketches of an ‘arrowhead’, a readily identified standard object, in the correct orientation. Magnitude is indicated by scaling the size of the arrowhead.

For use in raster graphics, arrowheads must be simple and have an unabiguous appearance in any orientation. Cones, cylinders, and spheres have been investigated, and results are given. A short, hockey-puck shaped cylinder with faces of contrasting colours appears to have good visual impact even when plotted to small scale in a discrete (raster graphics) display.

This shape is also easy to plot, and makes good use of available screen space. It is therefore recommended over the other candidate shapes.     

Hierarchical textures

Rich, interesting patterns create an oasis of aesthetic pleasure between the arid lands of complete randomness and complete order. In addition to their inherent beauty, patterns prove useful in graphics when we use them as textures. Textures were originally used to add color detail to shapes. Today, textures control everything from shape details to the placement of extras in digital crowd scenes. Though not appropriate for everything, such patterns can be used for applications from ornamentation to creating complex 3D structures and motion. One easy and powerful way to create rich textures is to start with something simple, and then use that seed along with some rules to “grow” something more complicated. Lots of growing schemes produce both repeating and non-repeating patterns. One of the simplest techniques is called “tiling”, where you place down multiple copies of a single starting shape, or tile, according to some (usually simple) rules. You can create rich tilings in surprisingly many ways. I look at a tiling technique based on using a set of simple symmetry operations     

基于增量式迭代变换的蜡染图形渐变算法

针对蜡染图形创新, 提出一种基于增量式迭代变换法的图形渐变方法, 即在不受特征点集对应的约束下, 实现两个平面图形之间自然、平滑渐变。该方法采用迭代渐变的思想, 对图形进行矢量预处理, 并分别在源矢量图形和目标矢量图形上采样一组几何特征点, 通过等分弧长对应的规则把两个图形进行权重归中, 对采样的节点求全局最小二乘进行特征匹配与映射, 再通过增量式迭代变换法得到一系列渐变中间图形。计算机仿真结果表明, 此算法能够较好地实现非特征对应的图形渐变, 达到过渡自然、平滑的目的。     

Learning Detail Transfer based on Geometric Features

The visual richness of computer graphics applications is frequently limited by the difficulty of obtaining high‐quality, detailed 3D models. This paper proposes a method for realistically transferring details (specifically, displacement maps) from existing high‐quality 3D models to simple shapes that may be created with easy‐to‐learn modeling tools. Our key insight is to use metric learning to find a combination of geometric features that successfully predicts detail‐map similarities on the source mesh; we use the learned feature combination to drive the detail transfer. The latter uses a variant of multi‐resolution non‐parametric texture synthesis, augmented by a high‐frequency detail transfer step in texture space. We demonstrate that our technique can successfully transfer details among a variety of shapes including furniture and clothing.     

Viewing geometric protein structures from inside a CAVE

We have developed general modeling software for a Cave Automatic Virtual Environment (CAVE); one of its applications is modeling 3D protein structures, generating both outside-in and inside-out views of geometric models. An advantage of the CAVE over other virtual environments is that multiple viewers can observe the same scene at the same time and place. Our software is scalable-from high-end virtual environments such as the CAVE, to mid-range immersive desktop systems, down to low-end graphics workstations. In the current configuration, a parallel Silicon Graphics Power Challenge supercomputer architecture performs the computationally intensive construction of surface patches remotely, and sends the results through the I-WAY (Information Wide Area Year) using VBNS (Very-high-Bandwidth Network Systems) to the graphics machines that drive the CAVE and our graphics visualization software, Valvis (Virtual ALpha shapes VISualizer)