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Texturen können als Oberflächenstrukturen realer Objekt aufgefasst werden und sind Variationen in Farbe, Geometrie, Transparenz, usw.. Im Gegensatz zu Algorithmen für die künstliche Generierung von Texturen gibt es nur wenige Ansätze zu Textur-Synthese-Sprachen oder zu Hilfsmittel für die Textur-Beschreibung. Die bekannten Werkzeuge decken zudem jeweils nur Teilgebiete der Generierung ab. Mit HiLDTe (Hierachical Language for the Description of Textures) ist nun eine Sprache entwickelt worden, mit der möglichst alle bekannten Texturtypen beschrieben werden können. HiLDTe basiert auf einem am Fachgebiet GRIS entwickelten Texturmodell, in dem Texturen generische, eventuell komplex zusammengesetzte Objekte repräsentieren. Aufgabe dieser Arbeit war es nun, Konzepte für die Sprache HiLDTe zu entwickeln, eine entsprechende Grammatik aufzubauen und mit Hilfe der UNIX-Werkzeuge LEX und YACC einen Compiler zu implementieren, mit dem ein ausführbarer Zwischen-Code für die in HiLDTe spezifizierten Texturen erstellt wird.
The Common Lisp Interface Manager (CLIM) is used to develop graphical user interfaces for Lisp-basedapplications. With the prototype of the CLIM interface Builder (CLIB) the programmer can generate code for CLIM interactively. The developing process will be fast and less prone to errors. With this new tool, the interactive rapid prototyping reduces costs of a specification phase. Here we present the concept and first results of the prototype of CLIB.
CAD/CAM techniques are used increasingly in dentistry for design and fabrication of teeth restorations. An important issue is preserving occlusal contacts of teeth after restoration. Traditional techniques based on the use of casts with mechanical articulators require manual adjustment of occlusal surface, which becomes impractical when hard restoration materials like porcelain are used; they are also time and labor consuming. Most existing computer systems ignore completely such an articulation check, or perform the check at the level of a tooth and its immediate neighbors. We present a new mathematical model and a related user interface for global articulation simulation, developed for the Intelligent Dental Care System project. The aim of the simulation is elimination of the use of mechanical articulators and manual adjustment in the process of designing dental restorations and articulation diagnostic. The mathematical model is based upon differential topological modeling of the jawbs considered as a mechanical system. The user interface exploits metaphors that are familiar to dentists from everyday practice. A new input device designed specifically for use with articulation simulation is proposed.
CAD/CAM techniques are increasingly used in dentistry for the design and fabrication of teeth restorations. Important concerns are the correction of articulation problems that existed beforetreatment and the prevention of treatment-generated problems. These require interactive evaluation of the occlusal surfaces of teeth during mastication. Traditional techniques based on the use of casts with mechanical articulators require manual adjustment of occlusal surfaces, which becomes impractical when hard restoration materials like porcelain are used; they are also time and labor consuming and provide little visual information. We present new visual tools and a related user interface for global articulation simulation, developed for the Intelligent Dental Care System project. The aim of the simulation is visual representation of characteristics relevant to the chewing process. The simulation is based on the construction of distance maps, which are visual representations of the distributions of the distances of points in a tooth to the opposite jaw. We use rasterizing graphics hardware for fast calculation of the distance maps. Distance maps are used for collision detection and for the derivation of various characteristics showing the distribution of load on the teeth and the chewing capability of the teeth. Such characteristics can be calculated for particular positions of the jaws; cumulative characteristics are used to describe the properties of jaw movement. This information may be used for interactive design of the occlusal surfaces of restorations and for jaw articulation diagnosis. We also demonstrate elements of a user interface that exploit metaphors familiar to dentists from everyday practice.
Design of a Helical Keyboard
(1996)
Inspired by the cyclical nature of octaves and helical structure of a scale (Shepard, '82 and '83), we prepared a model of a piano-style keyboard (prototyped in Mathematica), which was then geometrically warped into a left-handed helical configuration, one octave/revolution, pitch mapped to height. The natural orientation of upper frequency keys higher on the helix suggests a parsimonious left-handed chirality, so that ascending notes cross in front of a typical listener left to right. Our model is being imported (via the dxf file format) into (Open Inventor/)VRML, where it can be driven by MIDI events, realtime or sequenced, which stream is both synthesized (by a Roland Sound Module), and spatialized by a heterogeneous spatial sound backend (including the Crystal River Engineering Acoustetron II and the Pioneer Sound Field Control speaker-array System), so that the sound of the respective notes is directionalized with respect to sinks, avatars of the human user, by default in the tube of the helix. This is a work-in-progress which we hope to be fully functional within the next few months.
The PSFC, or Pioneer sound field control system, is a DSP-driven hemispherical 14-loudspeaker array, installed at the University of Aizu Multimedia Center. Collocated with a large screen rear-projection stereographic display the PSFC features realtime control of virtual room characteristics and direction of two separate sound channels, smoothly steering them around a configurable soundscape. The PSFC controls an entire sound field, including sound direction, virtual distance, and simulated environment (reverb level, room size and liveness) for each source. It can also configure a dry (DSP-less) switching matrix for direct directionalization. The PSFC speaker dome is about 14 m in diameter, allowing about twenty users at once to comfortably stand or sit near its sweet spot.
Dynamic characteristics of occlusion during lower jaw motion are useful in the diagnosis of jaw articulation problems and in computer-aided design/manufacture of teeth restorations. The Functionally Generated Path (FGP), produced as a surface which envelops the actual occlusal surface of the moving opponent jaw, can be used for compact representation of dynamic occlusal relations. In traditional dentistry FGP is recorded as a bite impression in a patient’s mouth. We propose an efficient computerized technique for FGP reconstruction and validate it through implementation and testing. The distance maps between occlusal surfaces of jaws, calculated for multiple projection directions and accumulated for mandibular motion, provide information for FGP computation. Rasterizing graphics hardware is used for fast calculation of the distance maps. Real-world data are used: the scanned shape of teeth and the measured motion of the lower jaw. We show applications of FGP to analysis of the occlusion relations and occlusal surface design for restorations.
Broader use of virtual reality environments and sophisticated animations spawn a need for spatial sound. Until now, spatial sound design has been based very much on experience and trial and error. Most effects are hand-crafted, because good design tools for spatial sound do not exist. This paper discusses spatial sound authoring and its applications, including shared virtual reality environments based on VRML. New utilities introduced by this research are an inspector for sound sources, an interactive resource manager, and a visual soundscape manipulator. The tools are part of a sound spatialization framework and allow a designer/author of multimedia content to monitor and debug sound events. Resource constraints like limited sound spatialization channels can also be simulated.
In an information-rich Virtual Reality (VR) environment, the user is immersed in a world containing many objects providing that information. Given the finite computational resources of any computer system, optimization is required to ensure that the most important information is presented to the user as clearly as possible and in a timely fashion. In particular, what is desired are means whereby the perspicuity of an object may be enhanced when appropriate. An object becomes more perspicuous when the information it provides to the user becomes more readily apparent. Additionally, if a particular object provides high-priority information, it would be advantageous to make that object obtrusive as well as highly perspicuous. An object becomes more obtrusive if it draws attention to itself (or equivalently, if it is hard to ignore). This paper describes a technique whereby objects may dynamically adapt their representation in a user's environment according to a dynamic priority evaluation of the information each object provides. The three components of our approach are:
- an information manager that evaluates object information priority,
- an enhancement manager that tabulates rendering features associated with increasing object perspicuity and obtrusion as a function of priority, and
- a resource manager that assigns available object rendering resources according to features indicated by the enhancement manager for the priority set for each object by the information manager.
We consider resources like visual space (pixels), sound spatialization channels (mixels), MIDI/audio channels, and processing power, and discuss our approach applied to different applications. Assigned object rendering features are implemented locally at the object level (e.g., object facing the user using the billboard node in VRML 2.0) or globally, using helper applications (e.g., active spotlights, semi-automatic cameras).