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Computer-supported assessment tools can bring significant benefits to both students and teachers. When integrated in traditional education workflows, they may help to reduce the time required to perform the evaluation and consolidate the perception of fairness of the overall process. When integrated within on-line intelligent tutoring systems, they could provide students with a timely feedback and support self-assessment activities. The current work presents an alternative approach (and not just a “yet-another-implementation”) to the problem of automatically evaluating technical skills needed to create 3D computer animations. Although some solutions have been reported already in the literature, their applicability is partially constrained, as they require the teaching staff to define evaluation criteria that are strictly linked to the particular animation technique being assessed. Students are forced to operate in environments where they can only perform a part of the required animation steps, by using a pre-defined set of techniques and tools. To address such limitations, the proposed system exploits shape- and time-based features extracted from the 3D point clouds (i.e., the set of data points) describing animated geometries, which are independent of the particular animation techniques used. Experimental observations collected in the evaluation of course assignments in which students were asked to recreate 3D animations of deformable meshes prepared by the teaching staff showed a good correlation between automatic and manual evaluations. Obtained results confirmed the ability of the proposed approach to cope with heterogeneous evaluation tasks in which the relevant learning outcomes can be properly considered.

The goal of this work is to investigate how the combination of 3D computer graphics and finite element software can be used to rapidly design materials with tunable properties for noise and vibration mitigation applications. Algorithms and software that create three-dimensional objects, known collectively as 3D computer graphics, are widely used artistically for rendering, animation, and game creation. These approaches allow for the design of complex topological structures such as cellular solids. This presentation describes the use of 3D computer graphics to design cellular structures, which can be imported into finite element software in order to determine effective vibrational properties. This approach is advantageous for several reasons. It allows for quick variation of parameters of cellular solids such as porosity and void fraction. It also is time efficient compared to alternative methods such as performing computed tomography scans on physical samples and analyzing the imaged files. Furthermore, r...

In one abstract view, computer graphics deals with building computer models or representations and then displaying them by some method or theory to produce a high-quality image. Computer vision is a dual to computer graphics. It starts with an image or animation and deduces the model representation for the computer. Computer graphics goes down from model to image, and computer vision goes up from image to model. This is, of course, a simplification, but it serves as a good basis to understand recent developments intersecting the two fields. Computer graphics and computer vision are truly complementary disciplines quickly approaching convergence. The broad study of computer-based imagery extends beyond these two fields to include the areas of human-computer interaction, visualization and image processing. Ongoing research and development will continue to forge this bond, and we'll begin to see real-world products emerge from these efforts. Then we will see the fruits of this convergence.

Deals with the development of algorithms to calculate the penetration curves of intersecting bodies. Although starting from ideas of a finite element environment where such procedures can be very helpful when generating complicated meshes, the algorithms also cover requirements of the describing geometry or computer graphics.

Surfaces designed in a computer graphics environment have many applications, including the design of cars, airplanes, shipbodies and modeling robots. The generation of smooth surfaces from a set of three-dimensional data points is a key problem in the field of Computer Aided Geometric Design. An overview of fundamental triangular concepts is given and new results are presented.

The author discusses the ten top problems of computer graphics, including topics such as geometric modeling, computer animation, creative information visualization and pixels.

In this chapter we'll discuss what is perhaps the most fundamental basis upon which three-dimensional (3D) graphics pipelines are built: computer representation of numbers, particularly real numbers. While 3D programmers often use the computer representations (approximations) of real numbers successfully without any understanding of how they are implemented, this can lead to subtle bugs and performance problems at inopportune stages in the development of an application. Most basic undergraduate computer architecture books [106] present the basics of integral data types (e.g., int and unsigned int, short, etc. in C/C++), but give only brief introductions to floating-point and other nonintegral number representations. Since the mathematics of 3D graphics are generally real-valued (as we shall see from the ubiquity of R, R 2 , and R 3 in the coming chapters), it is important for anyone in the field to understand the features, limitations, and idiosyncracies of the computer representation of these nonintegral types.

Simulating every day phenomena such as fluid, rigid objects, or cloth and their interaction has been a challenge for the computer graphics community for decades. In this article techniques to model such interactions are explained briefly and some of the result of applying these techniques are presented

Computer graphics concepts have a high visual component. For that reason, teaching this subject should be enriched with the use of small applications showing concepts like near and far plane or objects hierarchy in real time. However, their development is usually time consuming. In this paper we propose the use of an open source engine called Nebula to create such examples. We will show that Nebula applications are easy to develop and modify, presenting three small applications that help to explain important concepts in Computer Graphics curriculum.

Summary form only given. The field of computer graphics abounds with modeling and simulation problems. Among these are the representation of surface shape, the description of surface reflectance, the probabilistic modeling of small-scale variations, and the application of physics for simulating the dynamics of rigid and elastic materials. During its formative years, computer graphics has focused largely on developing algorithms and systems for performing efficient simulations that transform these analytic representations into images and animations. At present, the simulation framework for computer graphics is very mature. In last ten years, we have also witnessed significant technological developments in the areas of high-quality sensors and measurement devices. However, the data provided from these devices are frequently incompatible with the representations assumed by most computer graphics systems. The author explores new approaches to computer graphics that attempt to bridge the dichotomy between parametric and empirical modeling.

3-Draw is a tool for computer-aided design targeted at the early concept-forming stages of design. 3-Draw is intended to preserve the benefits of paper and pencil while taking advantage of the computer to develop, manipulate, and display 3-D representations of objects interactively. Designers using 3-Draw sketch out their initial ideas directly in three dimensions, using the computer to display objects in perspective and undergoing real-time motion. The hardware consists of two six-degrees-of-freedom sensors and a Silicon Graphics IRIS-4D/70GT graphics workstation. One sensor is configured to control an object's position and orientation. The other sensor is a multiconfigurable 3-D drawing/editing tool. Since the sketching is done directly in 3-D, the computer can generate limitless perspective views of models and the designer does not need to perform the image projection mentally. >

A novel surface representation scheme based on convolution integrals has been proposed for improving the efficiency of computer representation of surfaces. The representation is a parametric representation which uses (possibly complex) exponential functions instead of low-degree polynomials. Preliminary investigations indicate that the representation (under suitable restrictions) is robust and is applicable to a wide class of commonly occurring surfaces. >

We research the defects of geometric modeling in representing object attachments. It is difficult to represent different types of object attachments such as glueing or fusing in current computer graphics. We consider two types of different attachments such that an object is "put" on the top of another object, and an object is "fused" to the top of another object. To represent the relationships of object attachments, we assume a hypothesis such that we can represent the information of object attachments in computer graphics based on the cellular models, and consider the real implementation in computer graphics for proving that the cellular model of object attachments meet the hypothesis. The results of our research are expected to influence major applications including computer integrated manufacturing (CIM).

Modeling reflectance properties from real objects is useful for solving many practical problems ranging from industrial inspection to computer graphics. In particular building computer graphics models directly from real objects has received increased attention, because it is useful in many important fields such as CAD, entertainment (3D games, movies) and virtual museums. The paper describes an automatic way to recover actual reflectance parameters, from range and intensity (or color) data acquired from objects. The proposed approach is based on the Phong reflection model, since this model is usually preferred for computer graphics.

We consider mathematical formulas for description of geometrical surfaces. The list includes such surfaces as plane, second degree surfaces (16 types), second degree super surfaces (16 types), multiple surfaces (above second degree). All these surfaces are described only by a single equation. This equation has coefficients that define type, size, and location of a surface in 3D space. We can design and locate a surface by changing of the sign and value coefficients. In the library of a computer these surfaces are written in a parametrical form as a value of surface coefficients. It is a very compact library. We have software for creation of complex geometrical objects, if needed to convert object form, location of these objects in space scene, moving and rotation these objects in scene, visualization 3D stereo scene. We do not have a planar computer model, we create a computer analytical model as records of surface coefficients in the computer memory and proceed these coefficients for our tasks. The analytical model is very compact. Visualization has a complex procedure and requests some time but can be solved by an asynchronous super computer.

The creation of a virtual object for CAD/CAM and computer graphics on the base of data gathered by full-field optical measurement of 3D object is presented. The experimental co- ordinates are alternatively obtained by combined fringe projection/photogrammetry based system or fringe projection/virtual markers setup. The new and fully automatic procedure which process the cloud of measured points into triangular mesh accepted by CAD/CAM and computer graphics systems is presented. Its applicability for various classes of objects is tested including the error analysis of virtual objects generated. The usefulness of the method is proved by applying the virtual object in rapid prototyping system and in computer graphics environment.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Computer graphics is receiving much attention in the development of interactive educational software, multimedia systems, and many other applications. It not only adds a new dimension to such applications but also makes them more exciting and dynamic. Furthermore, the use of computer graphics is already well accepted in computer science education. If skillfully and relevantly used, it can be an important component of computer-assisted instruction, which is an educational application area with tremendous potential.

Object-orientation and computer graphics from a natural, if occasionally uneasy alliance. Tenets of object-orientation, such as data abstraction, instantiation, inheritance, and concurrency, also appear in the design and implementation of graphics design. We explore the relationship between object-orientation and computer graphics, and consider the structuring of various kinds of graphics systems in an object-oriented manner.

Computer graphics is a rapidly expanding field of science and technology, and education in this area is increasingly important. Development in computer graphics and the requirements of different applications have led to an explosion of subdisciplines.These share many fundamental principles, but each has a specialized orientation, with its own techniques and approaches to computer graphics. The basic disciplines, such as geometric modeling of single objects and 2D and 3D scenes, need efficient algorithms that involve computational geometry and knowledge of parallel computation. Other disciplines are oriented toward realistic visualization, and the enhancement of human/machine interaction leads to developing fields such as user interfaces, interactive modeling, multimedia and hypermedia and visual languages. A strong link is also required with related disciplines such as computer vision and image processing.Many of these subjects integrate knowledge derived from different sciences such as mathematics, physics, computer science and engineering, into a variety of applications. In Italy, computer graphics courses are taught in a number of curricula of traditional disciplines such as computer science, mathematics, physics, architecture and engineering. The choice was not to establish specific departments on computer graphics, but to give each discipline an overall sense of computer graphics as a subject into which they can fit their own specialities.This has led a number of universities to propose courses in computer graphics at both fundamental and advanced levels, especially in scientific departments. The variety of topics in computer graphics is so wide that they cannot be easily compressed in one course or a series of courses, but must be split according to the application requirements. A typical feature of computer graphics courses is that they are not usually intended for a single department's students, but they are of broad interest.

Since the early days of graphics the computer based representation of three-dimensional geometry has been one of the core research fields. Today, various sophisticated geometric modelling techniques including NURBS or implicit surfaces allow the creation of 3D graphics models with increasingly complex shape. In spite of these methods the triangle has survived over decades as the king of graphics primitives meeting the right balance between descriptive power and computational burden. As a consequence, today’s consumer graphics hardware is heavily tailored for high performance triangle processing. In addition, a new generation of geometry processing methods including hierarchical representations, geometric filtering, or feature detection fosters the concept of triangle meshes for graphics modelling. Unlike triangles, points have amazingly been neglected as a graphics primitive. Although being included in APIs since many years, it is only recently that point samples experience a renaissance in computer graphics. Conceptually, points provide a mere discretization of geometry without explicit storage of topology. Thus, point samples reduce the representation to the essentials needed for rendering and enable us to generate highly optimized object representations. Although the loss of topology poses great challenges for graphics processing, the latest generation of algorithms features high performance rendering, point/pixel shading, anisotropic texture mapping, and advanced signal processing of point sampled geometry. This talk will give an overview of how recent research results in the processing of triangles and points are changing our traditional way of thinking of surface representations in computer graphics - and will discuss the question: Are Points the Better Graphics Primitives?

Interactive computer graphics which implies a continuous exchange of information between the computer and the user has emerged as a very powerful tool in engineering applications. Computer-aided design (CAD) and computer-aided manufacturing (CAM) have found use in electronic circuit design, manufacturing, mapping, and architectural and engineering planning. Using CAD, a machine part, an electric circuit, or a building plan can be drawn and displayed on a video terminal. The product or plan can then be manipulated, rotated, viewed from different angles, or separated into segments. The graphic and attribute information related to the drawing is stored in a data base, and can be retrieved and modified at any time. At a more sophisticated level of CAD, the data base is used to generate input data for a finite element or another analysis program. This paper presents a brief survey of the CAD scene and the hardware and software available and describes the use of interactive graphics in generating data input for analysis.

'Surfaces in Computer Aided Geometric Design' focuses on the representation and design of surfaces in a computer graphics environment. This new area has the dual attractions of interesting research problems and important applications. The subject can be approached from two points of view: The design of surfaces which includes the interactive modification of geometric information and the representation of surfaces for which the geometric information is relatively fixed. Design takes place in 3-space whereas representation can be higher dimensional. 'Surfaces in CAGD' can be traced from its inception in rectangular Coons patches and Bezier patches to triangular patches which are current research topics. Triangular patches can interpolate and approximate to arbitrarily located data and require the preprocessing steps of triangulation and derivative estimation. New contouring methods have been found using these triangular patches. Finally, multidimensional interpolation schemes have been based on tetrahedral interpolants and are illustrated by surfaces in 4-space by means of color computer graphics.

The use of interactive computer graphics in CAD applications requires a great deal of programming effort. To avoid this effort many general display handlers and graphic languages have been written. They enable programming on a higher level as well as calls in a higher level programming language but they suffer from three disadvantages: they are oriented too much towards graphics and geometry, the handlers and languages are procedure oriented as opposed to problem oriented and modification in picture primitives requires re-programming and re-compiling. This paper proposes a method for defining general networks which overcomes these problems. (Received February 1973)

The simplest and earliest drawings of molecules had a line segment for each bond and could be modified in real time 1 . However, to understand the interaction of an enzyme with a substrate or inhibitor, or a drug or hormone with a receptor site, we must know the location of the molecular surface. Because the surfaces are so important, computer drawings have long been a useful tool in our understanding of the 3D structure of molecules. This article reviews various algorithms for representing these surfaces, either as unions of spheres or as other smoothed surfaces.

Computer Graphics is one of the most important, far-reaching, sophisticated, and glamorous endeavors of the computer field. It can be useful to every discipline that employs to advantage the computer. At the present time it is available for all the major computer areas—input, output, programming, and debugging. Whence did it originate? Exactly what is it and how can it be used? What are its future trends? These questions are considered in this article which divides Computer Graphics into two main divisions—passive and interactive. This article describes the most popular subdivisions of passive graphics—microfilm recorders and plotters—in detail. Computer Animation and Computer-generated movies as well as the main types of display devices are included under interactive graphics. This survey article considers the history of all the main types of computer graphics; discusses the typical hardware and main attributes as well as the advantages and disadvantages of each type; presents a section on computer-aided design, and a section on computer graphics professional groups and societies; and in its conclusion indicates some of the pit-falls of this powerful computing tool.

This paper presents fundamental results about how zero-curvature (paper) surfaces behave near creases and apices of cones. These entities are natural generalizations of the edges and vertices of piecewise-planar surfaces. Consequently, paper surfaces may furnish a richer and yet still tractable class of surfaces for computer-aided design and computer graphics applications than do polyhedral surfaces.

Deals with the emerging uses of computer graphics in the field of structural engineering and design, especially in the transference of numerical output into visual graphical form. Describes a Two-Dimensional Structure Analysis program through an IBM 360/50 Computer system at Lockheed-Georgia Laboratory. Civil Engineering is considered as a prime field for implementation of computer graphics, which would reduce calculation time; quantity of input would be reduced greatly by IBM program. Future expansion of computer graphics in engineering is described. Uses being developed presently include some which will display three-dimensional structural arrangements and permit broader man-machine interaction in input and output phases. Also under development is the kinematic analysis of three-dimensional mechanisms to optimize space requirements and maintain clearance. Computer graphics points the way toward better man-machine communication in all phases of design.

An important computer vision task is modeling of 3D objects for computer graphics and animation. This paper presents a method for generating a 3D wireframe model automatically out of a number of views of the original object. The silhouettes of the objects are used to determine the intersecting volume which represents a rough estimation of the object shape in voxel representation. A triangulation algorithm converts the model into a wire-frame surface representation to enhance the quality of the models surface and allow tex-ture mapping. A shape from motion/stereo algorithm is used to enhance the model shape. Calibrated cameras are used to obtain true dimensions.

Representing complex three-dimensional objects in a computer involves more than just evaluating its display capabilities. Other factors are the uses and costs of the representation, what operations can be performed on it and, ultimately, how useful it is for computer recognition or description or three-dimensional objects. Many of the questions which are posed arise from the joint consideration of computer graphics and computer vision, and a specific representation hierarchy is proposed for complex objects which makes them amenable to display, manipulation, measurement, and analysis.

During this decade, numerical models of mechanical parts have been exploited along with the activities related to computer aided design and manufacturing. Indeed, various types of engineering analysis in design have involved the representation problem of the object. N/C machining has required mathematical expressions of the surfaces to be machined for preparing the control information. Also systematical approaches to production require complete numerical representation of parts to provide efficient and smooth interface between design and manufacturing. This paper will describe one approach to parts representation and its applications.

SIMULATION AND COMPUTER AIDED GEOMETRIC DESIGN*Richard F. RiesenfeldUniversity of UtahSalt Lake City, Utah 84112AbstractThis paper discusses the traditional design process as it often applies to geometric design, and thenit examines a new organization of the design process in which computer simulation plays a central role.Some future developments in computer aided geometric design are anticipated.While the term computer simulation has had a rather strong statistical connotation in the past, it iscoming into more common use as a broader term that refers to a procedure that invokes a computer model, notnecessarily a statistical computer model. Computer graphics, or more precisely, image synthesis, hasdeveloped to the degree that it is now possible to generate relatively complex scenes in real -time with aconvincing semblance to "reality." This is to say, computer generated pictures are approaching the"reality" that one would see on a television monitor or on a photograph that reproduces a real life scene.We might say that in certain cases computer graphics has already passed the visual Turing test of synthe-sizing images which are indistinguishable to an observer from a corresponding nonsynthesized image.The advancement of computer graphics has also brought on a wide acceptance and preponderance of inex-pensive basic line drawing computer graphics equipment and techniques. A modern computing facility isexpected to offer some line drawing graphical devices like a storage tube terminal and a plotter for hard

The paper gives an approach to decision-making via application of the interactive computer graphics.