APPLICATION OF COMPUTER GRAPHICS IN MARTENSITIC TRANSFORMATION

This paper discuss the stereographic method of martensitic transformation (MT)in the view of computer graphics (CG) and programs are programmed to realize this method. Habit plane resulting from the programs agrees with that of numerical analysis in terms of the lattice parameters of austenite and martensite and shear mechanism supposed in Fe-22%Ni-0.8%C alloy, so does orientation relationships.

PHOTOREALISTIC COMPUTER GRAPHICS FORENSICS BASED ON LEADING DIGIT LAW

As the advent and growing popularity of image rendering software,photorealistic computer graphics are becoming more and more perceptually indistinguishable from photographic images.If the faked images are abused,it may lead to potential social,legal or private consequences.To this end,it is very necessary and also challenging to find effective methods to differentiate between them.In this paper,a novel leading digit law,also called Benford's law,based method to identify computer graphics is proposed.More specifically,statistics of the most significant digits are extracted from image's Discrete Cosine Transform(DCT) coefficients and magnitudes of image's gradient,and then the Support Vector Machine(SVM) based classifiers are built.Results of experiments on the image datasets indicate that the proposed method is comparable to prior works.Besides,it possesses low dimensional features and low computational complexity.

Dynamic Simulation of Shearer with 3D Computer Graphics

Based on computer graphics principle, technology and 3D graphics software, this paper deals with the 3D part design, assembly and animation of shearer in longwall integrated mechanized coal mining. The matixes of kinetic and geometry relationships and 3 dimension space coordinate systems are built for the cut drums, arms and shearer body. The methods of 3D modeling, dynamic simulation and relative technique problems are discussed.

Three-Dimensional Space Interpolation of Grey / Depth Image Sequence-A New Technique of Computer Graphics Synthesis

This paper advances a three-dimensional space interpolation method of grey / depth image sequence, which breaks free from the limit of original practical photographing route. Pictures can cruise at will in space. By using space sparse sampling, great memorial capacity can be saved and reproduced scenes can be controlled. To solve time consuming and complex computations in three-dimensional interpolation algorithm, we have studied a fast and practical algorithm of scattered space lattice and that of 'Warp' algorithm with proper depth. By several simple aspects of three dimensional space interpolation, we succeed in developing some simple and practical algorithms. Some results of simulated experiments with computers have shown that the new method is absolutely feasible.

From Sources to Narratives： The role of Computer Graphics in Communicating Cultural Heritage Information

During the last years, the topic of accessibility of cultural heritage is getting so important all around the Europe. For disseminating a research data and information, it is important to use a simple language and an effective communication. The data research produced by specialists has three formal levels： The third one of communication system aims to break barriers to reach a wide audience. The present study wants to demonstrate the role of images in the process of deductive inference by three dimensional （3D） reconstruction of cultural heritage. The case study of Federico da Montefeltro office shows how inter-disciplinary works and technological resource can help society to understand history and meaning of heritage.

Trends in Computer Graphics for the 1990's

We look at expected developments in computer graphics system capabilities for the next decade.the underlying thrust is an expected system hardware capability increase of around 50% per year.Memory sizes are expected to double every 12 to 18 months.Most of this system capability in- crease will be used in better and more elaborate simulations,detailed analyses of experimental and com- puted data(i.e.visualization)and more convenient user inputs.The overall effect by the end of the decade will be an increase in simulation capabilties of about fifty-fold,bringing affordable detailed analy- sis and interpretation of data to all engineering,scientific and business enterprises.Concomitant with these system growths is a need to re-examine graphics algorithms with the view of effectively utilizing the vastly increased memory sizes and employing specialized autonomous parallel computing structure.

Discriminating between photorealistic computer graphics and natural images using fractal geometry

Rendering technology in computer graphics （CG） is now capable of producing highly photorealistic images, giving rise to the problem of how to identify CG images from natural images. Some methods were proposed to solve this problem. In this paper, we give a novel method from a new point of view of image perception. Although the photorealistic CG images are very similar to natural images, they are surrealistic and smoother than natural images, thus leading to the difference in perception. A pert of features are derived from fractal dimension to capture the difference in color perception between CG images and natural images, and several generalized dimensions are used as the rest features to capture difference in coarseness. The effect of these features is verified by experiments. The average accuracy is over 91.2%.

Visual Simulation of Multiple Fluids in Computer Graphics： A State-of-the-Art Report

Realistic animation of various interactions between multiple fluids, possibly undergoing phase change, is a challenging task in computer graphics. The visual scope of multi-phase multi-fluid phenomena covers complex tangled surface structures and rich color variations, which can greatly enhance visual effect in graphics applications. Describing such phenomena requires more complex models to handle challenges involving the calculation of interactions, dynamics and spatial distribution of multiple phases, which are often involved and hard to obtain real-time performance. Recently, a diverse set of algorithms have been introduced to implement the complex multi-fluid phenomena based on the governing physical laws and novel discretization methods to accelerate the overall computation while ensuring numerical stability. By sorting through the target phenomena of recent research in the broad subject of multiple fluids, this state-of-the-art report summarizes recent advances on multi-fluid simulation in computer graphics.

Future Trends in Computer Graphics： How Much is Enough？

Over the forty-year history of interactive computer graphics, there have beencontinuous advances, but at some stage this progression must terminate with images beingsufficiently realistic for all practical purposes. How much detail do we really need? Polygon countsover a few million imply that on average each polygon paints less than a single pixel, making useof polygon shading hardware wasteful. We consider the problem of determining how much realism isrequired for a variety of applications. We discuss how current trends in computer graphics hardware,and in particular of graphics cards targeted at the computer games industry, will help or hinderachievement of these requirements. With images now being so convincingly realistic in many cases,critical faculties are often suspended and the images are accepted as correct and truthful althoughthey may well be incorrect and sometimes misleading or untruthful. Display resolution has remainedlargely constant in spatial terms for the last twenty years and in terms of the number of pixels hasincreased by less than an order of magnitude. If the long-promised breakthroughs in displaytechnology are finally realised, how should we use the increased resolution?

A review of computer graphics approaches to urban modeling from a machine learning perspective

Urban modeling facilitates the generation of virtual environments for various scenarios about cities.It requires expertise and consideration,and therefore consumes massive time and computation resources.Nevertheless,related tasks sometimes result in dissatisfaction or even failure.These challenges have received significant attention from researchers in the area of computer graphics.Meanwhile,the burgeoning development of artificial intelligence motivates people to exploit machine learning,and hence improves the conventional solutions.In this paper,we present a review of approaches to urban modeling in computer graphics using machine learning in the literature published between 2010 and 2019.This serves as an overview of the current state of research on urban modeling from a machine learning perspective.

A Computer Graphics-Based Framework for 3D Pose Estimation of Pedestrians

In pedestrian-to-vehicle collision accidents,adapting safety measures ahead of time based on actual pose of pedestrians is one of the core objectives for integrated safety.It can significantly enhance the performance of passive safety system when active safety maneuvers fail to avoid accidents.This study proposes a deep learning model to estimate 3D pose of pedestrians from images.Since conventional pedestrian image datasets do not have available pose features to work with,a computer graphics-based(CG)framework is established to train the system with synthetic images.Biofidelic 3D meshes of standing males are first transformed into several walking poses,and then rendered as images from multiple view angles.Subsequently,a matrix of 50 anthropometries,10 gaits and 12 views is built,in total of 6000 images.A two-branch convolutional neural network(CNN)was trained on the synthetic dataset.The model can simultaneously predict 16 joint landmarks and 14 joint angles of pedestrian for each image with high accuracy.Mean errors of the predictions are 0.54 pixels and−0.06°,respectively.Any specific pose can then be completely reconstructed from the outputs.Overall,the current study has established a CG-based pipeline to generate photorealistic images with desired features for the training;it demonstrates the feasibility of leveraging CNN to estimate the pose of a walking pedestrian from synthesized images.The proposed framework provides a starting point for vehicles to infer pedestrian poses and then adapt protection measures accordingly for imminent impact to minimize pedestrian injuries.

Call for Papers Special Issue of Tsinghua Science and Technology on Visualization and Computer Graphics

Tsinghua Science and Technology was started publication in 1996. It is an international academic journal sponsored by Tsinghua University and is published bimonthly. This journal aims at presenting the up-to-date scientific achievements in computer science and other IT fields. It is indexed by Ei and other abstracting indexes. From 2012, the journal enters into IEEE Xplore Digital Library

Blended Teaching Mode Based on“Cloud Class+PAD Class”in the Course of Computer Graphics and Image Design

As a teaching tool,Cloud class is specially developed for teaching and learning in mobile circumstance,and the PAD(Presentation Assimilation Discussion)class acts as a creative teaching mode.The combination of Cloud class and PAD class helps build online-offline blended teaching model.In this paper,a Cloud+PAD class mode is proposed.An experiment of teaching is implemented and the practical effectiveness is evaluated and verified.The experimental results show,compared with the conventional teaching method,the proposed teaching mode is capable of creating more high-level,innovative and complex teaching content,and thereby noticeably enhancing students’learner autonomy and motivating them to develop creativity.

CURDIS:A template for incremental curve discretization algorithms and its application to conics

We introduce CURDIS,a template for algorithms to discretize arcs of regular curves by incrementally producing a list of support pixels covering the arc.In this template,algorithms proceed by finding the tangent quadrant at each point of the arc and determining which side the curve exits the pixel according to a tailored criterion.These two elements can be adapted for any type of curve,leading to algorithms dedicated to the shape of specific curves.While the calculation of the tangent quadrant for various curves,such as lines,conics,or cubics,is simple,it is more complex to analyze how pixels are traversed by the curve.In the case of conic arcs,we found a criterion for determining the pixel exit side.This leads us to present a new algorithm,called CURDIS-C,specific to the discretization of conics,for which we provide all the details.Surprisingly,the criterion for conics requires between one and three sign tests and four additions per pixel,making the algorithm efficient for resource-constrained systems and feasible for fixed-point or integer arithmetic implementations.Our algorithm also perfectly handles the pathological cases in which the conic intersects a pixel twice or changes quadrants multiple times within this pixel,achieving this generality at the cost of potentially computing up to two square roots per arc.We illustrate the use of CURDIS for the discretization of different curves,such as ellipses,hyperbolas,and parabolas,even when they degenerate into lines or corners.

Graphics Evolutionary Computations in Higher Order Parametric Bezier Curves

This work demonstrates in practical terms the evolutionary concepts and computational applications of Parametric Curves.Specific cases were drawn from higher order parametric Bezier curves of degrees 2 and above.Bezier curves find real life applications in diverse areas of Engineering and Computer Science,such as computer graphics,robotics,animations,virtual reality,among others.Some of the evolutionary issues explored in this work are in the areas of parametric equations derivations,proof of related theorems,first and second order calculus related computations,among others.A Practical case is demonstrated using a graphical design,physical hand sketching,and programmatic implementation of two opposite-faced handless cups,all evolved using quadratic Bezier curves.The actual drawing was realized using web graphics canvas programming based on HTML 5 and JavaScript.This work will no doubt find relevance in computational researches in the areas of graphics,web programming,automated theorem proofs,robotic motions,among others.

COMPUTER SIMULATION IN MAN-MACHINE-ENVIRONMENT SYSTEM ENGINEERING

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HARDWARE-BASED VOXELIZATION FOR TRUE 3-D DISPLAY

An efficient voxelization algorithm is presented for polygonal models by using the hardware support for the 2 D rasterization algorithm and the GPU programmable function to satisfy the volumetric display system. The volume is sampled into slices by the rendering hardware and then slices are rasterated into a series of voxels. A composed buffer is used to record encoded voxels of the target volume to reduce the graphic memory requirement. In the algorithm, dynamic vertexes and index buffers are used to improve the voxelization efficiency. Experimental results show that the algorithm is efficient for a true 3-D display system.

Weight-based shape modification of NURBS curves by constrained optimization

A new method for shape modification of non-uniform rational B-splines (NURBS) curves was presented, which was based on constrained optimization by means of altering the corresponding weights of their control points. Using this method, the original NURBS curve was modified to satisfy the specified geometric constraints, including single point and multi-point constraints. With the introduction of free parameters, the shapes of modified NURBS curves could be further controlled by users without destroying geometric constraints and seem more naturally. Since explicit formulae were derived to compute new weights of the modified curve, the method was simple and easy to program. Practical examples showed that the method was applicable for computer aided design (CAD) system.

Constructing G^1 interpolation curves on surfaces with Coons surface

Using a bi-cubic Coons surface, a method for G1-continuous interpolation of an arbitrary sequence of points on an implicitly or parametrically defined surface with a specified tangent direction at every point was presented. Firstly construct a G1-continuous composite Coons surface patch, and then compute the intersection of the surface patch and the given surface. The desired interpolation curve is the intersection curve. Unlike some existing methods, several free parameters were introduced into the method that can be used in subsequent interactive modification so that the last curve's shape meets the demand. Experiments demonstrate the method is simple, feasible and applicable to computer aided design and computer graphics, etc.