Illumination And Color In Computer Generated Imagery

In a very broad sense the historical development of computer graphics can be considered in three phases, each a giant step down the road towards "realistic" computer generated images. The first, during the late 1960's and early 1970's, can perhaps be characterized as the "wire frame" era. Basically pictures were composed of lines. Considerable em phasis was placed on "real time" interactive manipulation of the model. As models became more complex and as raster technology developed, eliminating the hidden lines or hidden surfaces from the image became critical for visual understanding. This requirement resulted in the second phase of computer graphics, the "hidden surface" era, that developed during the 1970's and early 1980's. The names associated with hidden surface algorithms read like a who's who of computer graphics. The cul mination of the hidden surface era and the beginning of the current and third era in computer graphics, the "rendering" era, was Turner Whitted's incorporation of a global illumination model into the ray trac ing algorithm. Now the goal was not just to generate an image, but to generate a realistic appearing image.

The goal of this book is to present the most advanced research works in realistic computer generated images. It is made up of the papers presented during a Eurographics workshop that has been held in Rennes (France) on June 1990. Although realism in computer graphics has existed for many years, we have considered that two research directions can now clearly be identified. One makes use of empirical methods to efficiently create images that look real. As opposed to this approach, the other orientation makes use of physics to produce images that are exact representations of the real world (at the expense of additional processing time), hence the term photosimulation which indeed was the subject of this book. The objectives of this workshop were to assemble experts from physics and computer graphics in order to contribute to the introduction of physics-based approaches in the field of computer generated images. The fact that this workshop was the first entirely devoted to this topic was a bet and fortunately it turned out that it was a success. The contents of this book is organized in five chapters: Efficient Ray Tracing Meth ods, Theory of Global Illumination Models, Photometric Algorithms, Form-Factor Cal culations and Physics-Based Methods.

The focus of this book is on providing a thorough treatment of image processing with an emphasis on those aspects most used in computer graphics. Throughout, the authors concentrate on describing and analysing the underlying concepts rather than on presenting algorithms or pseudocode. As befits a modern introduction to this topic, a healthy balance is struck between discussing the underlying mathematics of the subject and the main topics covered: signal processing, data discretization, the theory of colour and different colour systems, operations in images, dithering and half-toning, warping and morphing, and image processing.

In the third paper in this chapter, Mike Pratt provides an historical intro duction to solid modeling. He presents the development of the three most freqently used techniques: cellular subdivision, constructive solid modeling and boundary representation. Although each of these techniques devel oped more or less independently, today the designer's needs dictate that a successful system allows access to all of these methods. For example, sculptured surfaces are generally represented using a boundary represen tation. However, the design of a complex vehicle generally dictates that a sculptured surface representation is most efficient for the 'skin' while constructive solid geometry representation is most efficent for the inter nal mechanism. Pratt also discusses the emerging concept of design by 'feature line'. Finally, he addresses the very important problem of data exchange between solid modeling systems and the progress that is being made towards developing an international standard. With the advent of reasonably low cost scientific workstations with rea sonable to outstanding graphics capabilities, scientists and engineers are increasingly turning to computer analysis for answers to fundamental ques tions and to computer graphics for present~tion of those answers. Although the current crop of workstations exhibit quite impressive computational ca pability, they are still not capable of solving many problems in a reasonable time frame, e. g. , executing computational fluid dynamics and finite element codes or generating complex ray traced or radiosity based images. In the sixth chapter Mike Muuss of the U. S.

Artificial Intelligence and Object-Oriented Technologies to Searching: An Algorithmic Tour

The three-volume set, LNCS 2667, LNCS 2668, and LNCS 2669, constitutes the refereed proceedings of the International Conference on Computational Science and Its Applications, ICCSA 2003, held in Montreal, Canada, in May 2003.The three volumes present more than 300 papers and span the whole range of computational science from foundational issues in computer science and mathematics to advanced applications in virtually all sciences making use of computational techniques. The proceedings give a unique account of recent results in computational science.

& Quot;Digital Video and HDTV Algorithms and Interfaces covers the theory and engineering of digital video systems in a manner that is equally accessible to video engineers and computer graphics practitioners. It provides succinct and accurate treatment of standard-definition television (SDTV), high-definition television (HDTV), and compression systems. & quot;--BOOK JACKET.

Possibly the most comprehensive overview of computer graphics as seen in the context of geometric modelling, this two volume work covers implementation and theory in a thorough and systematic fashion. Computer Graphics and Geometric Modelling: Implementation and Algorithms, covers the computer graphics part of the field of geometric modelling and includes all the standard computer graphics topics. The first part deals with basic concepts and algorithms and the main steps involved in displaying photorealistic images on a computer. The second part covers curves and surfaces and a number of more advanced geometric modelling topics including intersection algorithms, distance algorithms, polygonizing curves and surfaces, trimmed surfaces, implicit curves and surfaces, offset curves and surfaces, curvature, geodesics, blending etc. The third part touches on some aspects of computational geometry and a few special topics such as interval analysis and finite element methods. The volume includes two companion programs.