Salim S. Abi-Ezzi

TBAG: a high level framework for interactive, animated 3D graphics applications

We present a paradigm and toolkit for rapid prototyping of interactive, animated 3D graphics programs. The paradigm has its roots in declarative programming, emphasizing immutable values, first class functions, and relations, applying these concepts to a broad range of types, including points, vectors, planes, colors, transforms, geometry, and sound. The narrow role of modifiable state in this paradigm allows applications to be run in a collaborative setting (multi-user and multi-computer) without modification.

The Cone of Normals Technique for Fast Processing of Curved Patches

The cone of normals technique for curved surface patches allows to perform various quick tests at the patch level such as front‐ or backfacing test, light influence test, and existence of silhouette edges test. For a given patch, a truncated cone of normals is constructed at creation time, which contains all points and all normal directions of the patch. At traversal time, a simple scalar product test determines whether the whole patch is backfacing or frontfacing, so that the costly step of tessellating the patch is avoided in case of patch level face culling. In addition, the technique quickly determines which light sources have no influence on a patch, and which patches have no silhouette edges. The technique can also be used for other surface primitives, such as triangular strips and quadrilateral meshes,

Fast Dynamic Tessellation of Trimmed NURBS Surfaced1

Trimmed NURBS (non‐uniform rational B‐splines) surfaces are being increasingly used and standardized in geometric modeling applications. Fast graphical processing of trimmed NURBS at interactive speeds is absolutely essential to enable these applications. which poses some unique challenges in software, hardware, and algorithm design. This paper presents a technique that uses graphical compilation to enable fast dynamic tessellation of trimmed NURBS surfaces under highly varying transforms.

Functional 3D graphics in C++—with an object-oriented, multiple dispatching implementation

Constructing interactive, animated 3D graphics applications has been notoriously difficult for well over twenty years. Even though significant advances in the state- of-the-art have been made, this situation persists. The system described here simplifies the programmatic construction of geometry in ways that we have not seen elsewhere, and does so within the framework of an accepted production language, C++. It has been our experience that the resulting programs are quite succinct and comprehensible, and execute efficiently. The programmer is presented with a simple, general interface that is both declarative and conforms to the functional programming paradigm. Pursuing a functional interface for developing interactive 3D applications is a novel concept that, in our experience, has been successful in providing a simple, powerful interface and a relatively straightforward implementation. The implementation of the system is highly object-oriented, relying heavily upon multiple dispatching. The system itself is extensible and adding new geometric primitives and operations is straightforward. Entirely new media types, such as sound and image, may be (and have been) added to the system.

An Implementer's View of PHIGS

The Programmers Hierarchical Interactive Graphics System (PHIGS) specifies an interface for programming device-independent computer graphics applications. After a brief review of PHIGS concepts, an experimental environment used to study and evaluate the proposed standard is presented. The basic structure and distribution of function in this PHIGS implementation is discussed. We describe the architecture of a device-independent environment designed to realize the performance essential to the adequate functioning of a PHIGS implementation. The results presented emphasize the PHIGS output model. Full utilization of workstation processing capabilities, minimization of host/workstation interaction and efficient data management are key to our implementation.

A special graphics system for PHIGS

Abstract PHIGS specifies a high-level device independent interface to graphics systems. This interface emphasizes the modeling and articulation of hierarchically related graphical entities. It is essential that a graphics system supports the PHIGS functions at an adequate level of performance to achieve the articulations rapidly. A system is presented that is based on general purpose hardware modules assembled together in a special pipelined architecture to meet the above functional and performance needs. The main result is that the middle stages of the pipeline have similar requirements, and are best mapped to identical general purpose floating point processors. The design and performance of such a processor are discussed in detail. It is then shown how the system is expandable to meet foreseen future extensions to PHIGS. Finally, the suggested pipelined architecture is compared and contrasted to a parallel one.

An approach for a PHIGS machine

The Programmer’s Hierarchical Interactive Graphics System (PHIGS) proposal specifies a powerful interface for the development of interactive graphics applications. Throughout the development of PHIGS, emphasis has been placed on providing a high level of functionality along with the ability to provide rapid, dynamic display modifications. Any implementation of PHIGS should strive toward the ultimate goal of providing real-time support for the full functionality. This goal will be impossible to achieve using current, readily available graphics hardware. This is due to the inherent complexity introduced by the desired level of functionality and not to any of the specific approaches that PHIGS has taken to providing that functionality. One possible solution to this problem is the development of a “PHIGS machine.” Such a machine will play the role of a PHIGS logical workstation. This machine must include customized hardware to perform many of the functions required to meet the PHIGS specifications. Some of the more important PHIGS features which one must consider when approaching the architecture of such a machine include structure manipulation, structure traversal and the viewing pipeline.

The priority tree, a HL/HSR approach for PHIGS

The Programmers Hierarchical Interactive Grahics System (PHIGS) specifies an interface for programming device‐independent computer graphics applications. PHIGS provides a powerful data grouping mechanism, called the PHIGS structure, that may be used to model the geometry of 3D objects. Hidden Line/Hidden Surface Removal (HL/HSR) is a required process to produce realistic solid views of the modeled objects. Modeling clip is an essential process for viewing a clipped portion of the modeled objects. A technique is presented that provides HL/HSR and modeling clip as added utilities to PHIGS. The technique is based on the Binary Space Partitioning (BSP) tree (sometimes called priority tree), and involves a back to front sorting of the primitives of a PHIGS structure network to another PHIGS structure. Modeling clip is achieved by limiting the sorting to those primitives in a specified clip ping region of the object space. The resulting structure when displayed on a raster device produces a realistic view of the possibly clipped object that was originally modeled by the PHIGS structure network.

Extending graphics standards to meet industry requirements (panel session)

The presentation describes the plans for the National Weather Service central collection of radar products and distribution via the RPCCDS to allow the termination of the NEXRAD Information Dissemination Service (NIDS) agreements with three private sector vendors. The NIDS will be replaced by the RPCCDS and the NOAAPORT satellite broadcast. The NIDS agreements have been extended until December 31, 2000. A 30-day operational demonstration will be conducted to certify the operational readiness of the RPCCDS. The agreements will be further extended in 90-day increments only if the RPCCDS is not operational by that date. The central radar servers will offer both a multicast broadcast service of all radar products or a FTP access. Dedicated access to either requires a T1 line. Users of either service will be required to sign a Family of Services agreement for the new Radar Product Service and pay a one-time and annual fee (waived for Federal government users). The FTP server will also be accessible over Internet. No agreement or fees apply to Internet access.

Clarifications to the symbolic mode in REDUCE

I assume the readers knowledge of REDUCEs syntax, see [1,2]. The symbolic mode in REDUCE is best thought of as LISP presented in PASCAL like form. This mode should be used for system building and major enhancements to the algebraic mode, while most application programs will be written in algebraic mode.