Stereoscopic computer graphics for simulation and modeling

The advent of lead lanthanum zirconate titanate (PLZT) ceramics as electro-optic shutters in light weight, head-worn viewing devices has led to many recent applications for stereoscopic displays. PLZT stereoscopic viewers offer the advantage of essentially unrestricted freedom of head movement while achieving strong binocular depth-of-field sensations using a single CRT display. A survey of recent applications for field-sequential stereoscopic video and computer generated imagery is presented. Video applications include real-time color stereoscopic video for the Remote Underwater Work System (RUWS), a prototype stereoscopic x-ray imagery system, and moving platform stereoscopic imagery. Computer generated stereoscopic imagery applications include computer graphics simulations of an aircraft carrier landing sequence, computer modeling of double helix DNA molecular structures, and stereoscopic displays derived from multispectral satellite imagery.

A recently discovered photoferroelectric (PFE) effect in which the electric-field-induced antiferroelectric (AFE)-to-ferroelectric (FE) phase transition is photoinhibited is used to store nonvolatile gray-scale images in lead lanthanum zirconate titanate (PLZT) ceramics. Stored images exhibit exceptionally high contrast and approximately linear gray-scale reproduction. Images are stored as spatial variations of the volume ratio of FE phase to the initial AFE phase. Localized variations of the ratio of FE to AFE phase produce related variations in light scattering. In the materials studied, the scattering effect partially depolarizes transmitted visible light, and the stored image can be viewed directly or projected onto a screen using crossed linear polarizers.

This book presents the steps necessary for the application of rotorcraft flight modelling and simulation and analysis in support of certification for compliance with EASA CS-27 and CS-29, SUBPART B—FLIGHT and other flight-related rules (e.g. CS-27/9, Appendix B, Airworthiness Criteria for Helicopter Instrument Flight). The material is presented in the form of a structured ‘Rotorcraft Certification by Simulation’ process, starting from the relevant paragraphs in the Certification Specifications, through a comprehensive description of the assembly of flight simulation requirements, informed by judgements on Influence, Predictability and Credibility, and on into the detailed building of the three major elements of the process; the Flight Simulation Model, the Flight Simulator, and the associated Flight Test Measurement System.

Digital projectors based on liquid crystal or micro-mirror technologies provide higher spatial resolution than the CRTs typically used in flight-simulator applications. However, their temporal response is limited by long hold-times. Hold-time is the interval that pixels are activated during each frame, and it is related to both the design of the driver circuitry and the display itself. Long hold-times result in the blurring of moving imagery, which can affect the detection and identification of simulated targets as well as the perceived realism of simulated scenes. Described here are the results of an evaluation of several digital projectors that implement various techniques for reducing pixel hold-time. The evaluation included estimates of both spatial and temporal resolution, as well as perceptual tests used to assess the validity of those estimates. The techniques described here can be used to assess the potential utility of candidate projectors for a given simulator application. The following projectors were tested: ferro-electric liquid crystal on silicon (FLCoS), liquid crystal on silicon (LCoS), liquid crystal (LCD), digital light projector (DLP, a digital micro-mirror device, or DMD), and cathode ray tube (CRT). The hold-time of the FLCoS and LCD projectors was varied using mechanical shutters, and the hold-time of the DLP projector was varied using an electronic shutter. The CRT and LCD projectors were used mainly for comparison and so their hold-times were not varied.

Modern stereoscopic 3D (S3D) cinematic production relies heavily on digital tools and pipelines. Although technically possible, avoiding digital processing of the images is not only unlikely, but will probably yield worse results, since digital tools and pipelines inherently solve many of the issues found in traditional S3D film production and present the opportunity to correct for many others. All computer graphics (CG) tools are based on an implicit or explicit camera model. The model is even more overt in S3D productions and presents more complex implications and ramifications throughout the production pipeline. In this paper, the impact of the camera model on various processes in a production pipeline will be explored and some methods are proposed to improve efficiency with a savvy generation, recording, transport and use of metadata.

Quasi-period cylindrical nanostructures with both diameters and intervals of about 100nm are manufactured on the surfaces of Nd3+-doped lanthanum lead zirconate titanate ceramics by femtosecond laser irradiation under SF6 atmosphere. A light-emission enhancement of more than 20 times is investigated, accompanied by an extremely long trailing-off time of light emission and lower threshold. A specific polarization state of the light emission is achieved and tuned by changing the incident regions of the pumping source. The increased absorption coefficient of the specimen is discussed based on multiple scattering and weak localization of light. In addition, both the scatterers provided by the laser-machined nanostructure and the recurrent photoinduced trapping and re-excitation process participated in the enhancement of the light emission. This Letter offers new insight to improve the luminescence property of laser materials, as well as to broaden the range of exploring the weak localization of light and random lasers.

Erratum of Europhys. Lett. 48 (3) pp. 326-331 (1999)

A detailed study of the polarization and depolarization behavior of 7:65:35 and 8:65:35 lead lathanum zirconate titanate transparent ceramics under dc bias and constant heating rates has been carried out. The dielectric permittivity exhibits a new anomaly near 0 °C in freshly thermally depoled samples which is associated with a buildup of macrodomains and the development of a remanent polarization. From continuity of the dispersive behaviors it is suggested that the dielectric change at the so-called α–β transition Td is not a conventional phase change, but rather is a loss of macro-ordering and a decay back to a disordered microdomain texture.

Photovoltaic properties of lead lanthanum zirconate titanate ceramics in a layered film structure design

Effect of composition and grain size on dielectric, ferroelectric and induced strain behavior of PLZT/ZrO2 composites

This paper presents a comparison of the motion produced by a flight simulator using conventional washout filters and a novel robust controller. Both approaches are implemented in an off-line Matlab/Simulink simulation which includes a model of an electrically-driven synergistic motion base flight simulator. In order to evaluate the performance of these motion base control approaches, the Boeing 747 airliner has been simulated using a nonlinear model of its dynamics. The motion experienced by the aircraft pilot is compared to that experienced by the simulator pilot, using both control approaches. Additionally, the model used for the simulator motion base is adjusted to represent two different scenarios: a highand a low-fidelity motion system. It is shown that the two control approaches reasonably track the motion of the aircraft, within the limitations of the motion base, but that the robust controller is able to compensate for variations in the fidelity of the motion system.

In the late 1960s, artists and engineers began building increasingly sophisticated video synthesizers, machines that produced abstract or distorted images by electronically manipulating either a video signal or the cathode ray tube on which it was displayed. This article explores how experimental videographers modeled video synthesizers on audio synthesizers, conceptualized them as analog computers, and starting in 1973, interfaced them with digital minicomputers. They used digital computers first as programmable controllers for complex analog synthesizers and then as sources of digital imagery themselves, integrating video and computer graphics in hybrid analog/digital systems.

This paper studies the feasibility of applying the stochastic gain tuning method to the flight control system design of space vehicles. Stochastic gain tuning is a form of parameter optimization by which. the probability of the flight control system’s total mission achievement is maximized. This probability is estimated by applying the Monte Carlo method to the results of a large number of simulated flights. The flight simulation model contains various types of uncertain parameter, the stochastic properties of which are defined a priori. The flight control system requirements are defined based on the flight simulation results, and an optimization algorithm called the mean tracking technique is used to tune the feedback/feedforward gains of the flight control laws, which maximizes the probability of mission achievement. Although stochastic gain tuning requires large computational resources, the recent advent of low-cost, high-performance computers means that it has become feasible and practicable if efficient computational algorithms are employed. This paper demonstrates its feasibility by applying it to the designof the flight control system of a re-entry space vehicle, a low-speed sub-scaled model of which was flight tested in 1996.

The basic principle of electrophotographic non-impact printers is to expose a photoconductor by a light beam which is modulated by the information to be printed and to process the latent image in the same way as usually done in plain paper office copiers. Key components of non-impact printers to be matched are, therefore, light source and photoconductor. Currently used light sources and light shutters are gas and solid-state lasers, cathode ray tubes (CRT, OFT), light emitting diodes (LED), magneto-optical light shutters (LISA) , liquid crystal light shutters (LCS) , and electrooptical light shutters (PLZT-ceramics). Photoconductors are: selenium based materials (amorphous Se-based alloys, As2Se0, binder layers (mainly CdS), organic photoconductors (OPC), and amorphous silicon (a-Si).

A vision–based 3‐D scene analysis system is described that is capable to model complex real–world scenes like streets and buildings automatically from stereoscopic image pairs. Input to the system is a sequence of stereoscopic images taken with two standard CCD Cameras and TV lenses. The relative orientation of both cameras to each other is known by calibration. The camerapair is then moved throughout the scene and a long sequence of closely spaced views is recorded. Each of the stereoscopic image pairs is rectified and a dense map of 3‐D suface points is obtained by area correlation, object segmentation, interpolation, and triangulation. 3‐D camera motion relative to the scene coordinate system is tracked directly from the image sequence which allows to fuse 3‐D surface measurements from different viewpoints into a consistent 3‐D model scene. The surface geometry of each scene object is approximated by a triangular surface mesh which stores the suface texture in a texture map. From the textured 3‐D models, realistic looking image sequences from arbitrary view points can be synthesized using computer graphics.