Computer Graphics Tools for Rendering Algebraic Surfaces and for Geometry of Order

Computer graphics tools and techniques enable researchers to investigate cultural heritage and archaeological sites. They can facilitate documentation of real-world sites for further investigation, and enable archaeologists and historians to accurately study a past environment through simulations. This chapter explores how light plays a major role in examining computer-based representations of heritage. We discuss how light is both documented and modelled today using computer graphics techniques and tools. We also identify why both physical and historical accuracy in modelling light is becoming increasingly important to study the past, and how emerging technologies such as High Dynamic Range (HDR) imaging and physically-based rendering is necessary to accurately represent heritage.

The purpose of this volume is to present current work of the Intelligent Computer Graphics community, a community growing up year after year. Indeed, if at the beginning of Computer Graphics the use of Artificial Intelligence techniques was quite unknown, more and more researchers all over the world are nowadays interested in intelligent techniques allowing substantial improvements of traditional Computer Graphics methods. The other main contribution of intelligent techniques in Computer Graphics is to allow invention of completely new methods, often based on automation of a lot of tasks assumed in the past by the user in an imprecise and (human) time consuming manner. This volume contains both invited and selected extended papers from the last 3IA Conference (3IA2008), together with an introduction presenting the area of Intelligent Computer Graphics and various Computer Graphics areas where introduction of intelligent techniques permitted to resolve important problems. We hope that this volume will be interesting for the reader and that it will convince him (her) to use, or to invent, intelligent techniques in Computer Graphics and, maybe, to join the Intelligent Computer Graphics community.

Once again, we discuss graphic display and interaction. This time, we try to provide a context for JOEY within the history and evolution of techniques in computer graphics and user interface design. If working with this text is your first exposure to 3D graphics, you undoubtedly have a lot of questions about how things are done (and how they were done before). If you have been working in graphics for awhile, you may be wondering how some of the unorthodox approaches in JOEY relate to previous work. This section should help to answer both questions.

Recent advances in acquisition technologies, such as LIDAR and photogrammetry, have brought back to popularity 3D point clouds in a lot of fields of application of Computer Graphics: Civil Engineering, Architecture, Topography, etc. These acquisition systems are producing an unprecedented amount of geometric data with additional attached information, resulting in huge datasets whose processing and storage requirements exceed usual approaches, presenting new challenges that can be addressed from a Big Data perspective by applying High Performance Computing and Computer Graphics techniques. This chapter presents a series of applications built on top of Point Cloud Manager (PCM), a middleware that provides an abstraction for point clouds with arbitrary attached data and makes it easy to perform out-of-core operations on them on commodity CPUs and GPUs. Hence, different kinds of real world applications are tackled, showing both real-time and offline examples, and render-oriented and computation-related operations as well.

Unlike textbook images that are static and television images that permit only passive viewing, computer graphics can be drawn dynamically and interactively on the display screen. For years, most computer games have featured animated, interactive computer graphics. Now computer-based tutorials on a wide range of topics are available that present new information to learners via dynamic, interactive graphics. One of the most recent developments in the area of computer graphics is the educational use of graphics applications software—the visual equivalent of word processing software. With it, learners can create their own computer graphics on the display screen and then use the computer to review the images in a variety of ways. Images can be enlarged, flipped, rotated, animated, duplicated, colored, sized up or down, moved around the screen, deleted, and more—all without programming. It is this dynamic and interactive aspect of computer graphics that is so appealing to learners and holds great promise for improving instruction.

In recent years, Computer Graphics (CG) and related techniques have become increasingly important for the preservation and dissemination of Cultural Heritage (CH). Here we present a set of three excellent CH reconstructions and virtual heritage experiences created by final year undergraduate students from several computer animation related programmes of study in the course of an optional course on “CG and Animation for Cultural Heritage”. The three projects discussed here are interactive heritage experiences, including a reconstruction of the tomb of Tutankhamun, an Augmented Reality (AR) reconstruction of the Iron Age hillfort Maiden Castle, and a Virtual Reality (VR) reconstruction of ancient Stonehenge.

This paper presents a survey of ocean simulation and rendering methods in computer graphics. To model and animate the ocean’s surface, these methods mainly rely on two main approaches: on the one hand, those which approximate ocean dynamics with parametric, spectral or hybrid models and use empirical laws from oceanographic research. We will see that this type of methods essentially allows the simulation of ocean scenes in the deep water domain, without breaking waves. On the other hand, physically‐based methods use Navier–Stokes equations to represent breaking waves and more generally ocean surface near the shore. We also describe ocean rendering methods in computer graphics, with a special interest in the simulation of phenomena such as foam and spray, and light’s interaction with the ocean surface.

This paper presents an interactive graphics tool for the structural analysis of one‐dimensional element models, such as trusses, frames, and grillages. The focus is on the creation of a graphical user interface for a previously developed analysis solver. This graphical interface is entirely implemented in the MATLAB environment and features intuitive resources so that modeling and verification of results become easy tasks for students and engineers. The management of mouse events and the adopted solutions to basic computer graphics issues that arise from interactive modeling in two‐dimensional and three‐dimensional canvases are discussed, including the strategies to pick objects in spatial coordinates and to identify crossing elements. The result is a new educational software that proved to be a very useful application in structural analysis and introductory computer graphics courses for engineering. The article also presents examples of using the software as an educational tool.

KEY ISSUES IN INSTRUCTIONAL COMPUTER GRAPHICS

The first major computer graphics text, Principles of Interactive Computer Graphics,1 was inspired by a course, a research project, and a set of notes, all by Ivan Sutherland. In 1971, William Newman invited me to join forces to supplement his partial book draft with notes I had been writing. The book, which appeared in 1973, was received well, exceeding the sales projections of its publisher, McGraw-Hill. Between 1973 and 1977, William and I were research staff at the Xerox Palo Alto Research Center (PARC) working on tools for an “office of the future,” focusing especially on interactive graphics and raster printing. We realized that raster displays and printers would soon dominate and would require mastering new techniques and adapting old ones. The second edition of our book, a complete rewrite, introduced some of the new technologies. This note is a story of the writing of the two editions of the book and it is also a story about how the editions were published in the era before commercial desktop publishing systems. In both the cases, we exploited and adapted computer tools of the time to do much of the publishing ourselves. For the second edition, we chose to use the illustration and printing tools we had developed at PARC to produce camera-ready copy. Especially significant was the use of the Press file format, an early page description language, to combine onto each page the various separate components prepared by different composition tools.

Advancement in information and communication technology has led to tremendous development in graphics techniques. Evolving multimedia tools are used to generate high quality Computer Graphics (CG) images. These images have wide applications in domains like video gaming, augmented reality, and virtual reality and many other. Computer graphic images are also used illegally in criminal activities. This article proposes an effective transfer learning approach to classify CG and Photographic (PG) images available in small scale dataset. Initially, pre-trained models such as AlexNet, GoogleNet, ResNet50, VGG-18 and SqueezeNet were modified and fine-tuned appropriately. Based on the validation accuracy, SqueezeNet was adapted as learning model for extracting deep features for classification. To evaluate the performance of squeezeNet, Columbia dataset and Photo realistic dataset were used. Finally, the performance of the proposed model was compared with state-of-the- art transfer learning approaches to prove its efficacy. Accuracy of 93.75% was attained using SqueezeNet for the folding ratio 80:20 when the input data is augmented.

This course presents an elementary, intuitive, and visual introduction to several mathematical basics for beginners in computer graphics. The mathematical concepts covered in this course include 2D/3D translation, rotation, affine transformation, quaternion, dual quaternion, exponential and logarithm. These are quite useful for various aspects of computer graphics, including curve/surface editing, deformation and animation of geometric objects. On one hand we don't assume that the audience has familiarity with such mathematical concepts. Elements of linear algebra and calculus at undergraduate level are sufficient for the attendees of this course. To clarify the relation between these concepts and computer graphics practice, several graphics techniques will also be demonstrated, such as morphing (ARAP), cage-based deformation and Poisson mesh editing.

Even though rendering techniques in computer graphics have greatly progressed, it is still required that more realistic images with a short calculation time be generated. It is particularly desirable to put in objects without taking time and display these objects with a short calculation time. This paper proposes efficient techniques for rendering objects with rounded edges, complex objects composed of numerous simple elements such as transmission towers, and extremely thin objects such as transmission lines and curtains.

Morphing between 3D objects is a fundamental technique in computer graphics. Traditional methods of shape morphing focus on establishing meaningful correspondences and finding smooth interpolation between shapes. Such methods however only take geometric information as input and thus cannot in general avoid producing unnatural interpolation, in particular for large‐scale deformations. This paper proposes a novel data‐driven approach for shape morphing. Given a database with various models belonging to the same category, we treat them as data samples in the plausible deformation space. These models are then clustered to form local shape spaces of plausible deformations. We use a simple metric to reasonably represent the closeness between pairs of models. Given source and target models, the morphing problem is casted as a global optimization problem of finding a minimal distance path within the local shape spaces connecting these models. Under the guidance of intermediate models in the path, an extended as‐rigid‐as‐possible interpolation is used to produce the final morphing. By exploiting the knowledge of plausible models, our approach produces realistic morphing for challenging cases as demonstrated by various examples in the paper.

In the past thirty years, modeling techniques in computer graphics have evolved significantly as the field has matured and attempted to portray the complexities of nature. Polygonal models, patches, points, and lines are insufficient to represent the complexities of natural objects and intricate man-made objects in a manageable and controllable fashion. Higher-level modeling techniques have been developed to provide an abstraction of the model, encode classes of objects, and allow high-level control and specification of the model. The goal of these advanced modeling techniques is to provide a concise, efficient, flexible, and controllable mechanism for specifying and animating models of complex objects and natural phenomena. Most of these advanced modeling techniques can be considered procedural modeling techniques: code segments or algorithms are used to abstract and encode the details of the model instead of explicitly storing vast numbers of low-level primitives. The use of algorithms unburdens the modeler/animator of low-level control, provides great flexibility, and allows amplification of his efforts through parametric control: a few parameters to the model yield large amounts of geometric details (Smith [1984] called this “database amplification”). This survey examines several types of procedural techniques, including fractals, grammar-based models, volumetric procedural models, implicit surfaces, and particle systems.