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Der Programmier System Generator - PSG - des Fachgebiets Praktische Informatik in Darmstadt erzeugt aus einer Sprachdefinition eine sprachspezifische Programmierumgebung. Diese besteht u. a. aus einem Editor, welcher syntaktische und semantische Fehler von Programmfragmenten, die nicht vollständig sein müssen, erkennen kann. Dem Benutzer werden per Menü Fehlerkorrekturen angeboten. Neben der freien Texteingabe besteht die Möglichkeit, den Text nur mit Hilfe von Menüs zu verfeinern. Teil dieses Editors ist die Bezeichneranalyse. Sie dient als Hilfsmittel für den Benutzer, indem für jede Stelle eines Programmfragmentes die gültigen Bezeichner ausgegeben werden können. Die Kontextanalyse setzt die Berechnung auf den von der Bezeichneranalyse erzeugten Daten auf, um semantische Fehler zu erkennen. Die bis zu dieser Arbeit verwendete Bezeichneranalyse im PSG unterstützt nur einfache Sprachkonzepte (z. B. Fortran und Pascal). Die Gültigkeitskonzepte der Bezeichner von weiterentwickelten Sprachen (z. B. Modula-2, CHILL, Ada oder Pascal-XT) sind nicht vollständig modellierbar. Wir stellen ein neues Konzept zur Definition und Berechnung der Bezeichneranalyse vor, das alle uns bekannten Sprachen mit statischer Typbindung unterstützt. Hierfür haben wir die Sprache BIS - Bezeichneridentifikationssprache - definiert. Die Methode ist verwandt mid dem Zwischencode für geordnete Attributierte Grammatiken. Für jeden Knoten des Abstrakten Syntaxbaumes wird mit Hilfe von BIS ein Code für eine abstrakte Maschine, welche die Bezeichneranalyse durchführt, geschrieben. Im Gegensatz zu herkömlichen Methoden (verkettete Symboltabellen) wird für jeden Punkt innerhalb eines Programmes for der Anfrage durch den Benutzer oder der Kontextanalyse die Menge der gültigen Bezeichner berechnet. Die Kosten für eine Anfrage sind dadurch minimal. Diese abstrakte Maschine teilt sich in zwei unabhängige Maschinen auf, zum einen in die S-Maschine, die die speziellen Operationen der Bezeichneranalyse durchführt, und zum anderen in die G-Maschine, die den Datenfluss und die Auswertung steuert. Diese Aufteilung ermöglicht den Austausch der S-Maschine durch eine andere, welche neue Anwendungsgebiete erschliesst, z. B. die eines Praeprozessors. Die G-Maschine arbeitet inkrementell; es werden nur die Codeschablonen neu ausgewertet, deren geerbten Attribute sich geändert haben. Dazu müssen die Daten, die in einer Codeschablone hinein- und hinausfliessen, abgelegt werden. Dies ergibt bei grossen Programmfragmenten eine immense Rechenzeiteinsparung auf Kosten des Speicherplatzes. Die Funktionsweise wird an einer kleinen Beispielsprache demonstriert, die zu Pascal ähnlich ist. Diese besitzt Konstrukte zum Import und Export von Daten und Datentypen zwischen Programmfragmenten. Im Prototyp kann die inkrementelle Arbeitsweise abgeschaltet werden und ermöglicht einen guten Vergleich der Verfahren.
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.
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.
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).
Information Retrieval and Database Architecture for Conventional Japanese Character Dictionaries
(1997)
The cycle of abstraction-reconstruction which occurs as a fundamental principle in the development of culture and in cognitive processes is described and analyzed. This approach leads to recognition of boundary conditions for and directions of probable development of cognitive tools. It is shown how the transition from a conventional Japanese-English character dictionary to a multi-dimensional language database is an instance of such an abstraction-reconstruction cycle. The different phases of the design of a multi-dimensional language database based upon different computer software technologies are properly placed in this cycle. The methods used include the use of UNIX software tools, classical database methods as-well-as the use of search engines based upon full text search in this process. Several directions of application and extension for a multi-dimensional language database are discussed from the general point of view of an abstraction-reconstruction cycle.
In a virtual reality environment users are immersed in a scene with objects which might produce sound. The responsibility of a VR environment is to present these objects, but a system has only limited resources, including spatialization channels (mixels), MIDI/audio channels, and processing power. The sound spatialization resource manager controls sound resources and optimizes fidelity (presence) under given conditions. For that a priority scheme based on human psychophysical hearing is needed. Parameters for spatialization priorities include intensity calculated from volume and distance, orientation in the case of non-uniform radiation patterns, occluding objects, frequency spectrum (low frequencies are harder to localize), expected activity, and others. Objects which are spatially close together (depending on distance and direction) can be mixed. Sources that can not be spatialized can be treated as a single ambient sound source. Important for resource management is the resource assignment, i.e., minimizing swap operations, which makes it desirable to look-ahead and predict upcoming events in a scene. Prediction is achieved by monitoring objects’ speed and past evaluation values. Fidelity is contrasted for Zifferent kind of resource restrictions and optimal resource assignment based upon unlimited dynamic scene look-ahead. To give standard and comparable results, the VRML 2.0 specification is used as an application programmer interface. Applicability is demonstrated with a helical keyboard, a polyphonic MIDI stream driven animation including user interaction (user moves around, playing together with programmed notes). The developed sound spatialization resource manager gives improved spatialization fidelity under runtime constraints. Application programmers and virtual reality scene designers are freed from the burden of assigning and predicting the sound sources.