72 research outputs found

    3D Scanning, Imaging, and Printing in Orthodontics

    Get PDF

    THE ADVANTAGES OF MODEL 4807A HIGH RESOLUTION ACCELEROMETER

    Get PDF
    This paper is aimed to inform the advantages of model 4807A accelerometer as device of measurement base on literature review. The model 4807A accelerometer is produced by Measurement Specialties, Inc. It has many advantages such as hermetically sealed and offers an amplified signal output covering ranges from ± 2 g to ± 200 g, and built-in mechanical overload stops for shock protection to 5,000 g. This model accelerometer can be applied in many fields, such as Vibration Isolation, Flight Testing, Trajectory Profiling, Structural Monitoring, and Researches & Development

    SPATIO-TEMPORAL REGISTRATION IN AUGMENTED REALITY

    Get PDF
    The overarching goal of Augmented Reality (AR) is to provide users with the illusion that virtual and real objects coexist indistinguishably in the same space. An effective persistent illusion requires accurate registration between the real and the virtual objects, registration that is spatially and temporally coherent. However, visible misregistration can be caused by many inherent error sources, such as errors in calibration, tracking, and modeling, and system delay. This dissertation focuses on new methods that could be considered part of "the last mile" of spatio-temporal registration in AR: closed-loop spatial registration and low-latency temporal registration: 1. For spatial registration, the primary insight is that calibration, tracking and modeling are means to an end---the ultimate goal is registration. In this spirit I present a novel pixel-wise closed-loop registration approach that can automatically minimize registration errors using a reference model comprised of the real scene model and the desired virtual augmentations. Registration errors are minimized in both global world space via camera pose refinement, and local screen space via pixel-wise adjustments. This approach is presented in the context of Video See-Through AR (VST-AR) and projector-based Spatial AR (SAR), where registration results are measurable using a commodity color camera. 2. For temporal registration, the primary insight is that the real-virtual relationships are evolving throughout the tracking, rendering, scanout, and display steps, and registration can be improved by leveraging fine-grained processing and display mechanisms. In this spirit I introduce a general end-to-end system pipeline with low latency, and propose an algorithm for minimizing latency in displays (DLP DMD projectors in particular). This approach is presented in the context of Optical See-Through AR (OST-AR), where system delay is the most detrimental source of error. I also discuss future steps that may further improve spatio-temporal registration. Particularly, I discuss possibilities for using custom virtual or physical-virtual fiducials for closed-loop registration in SAR. The custom fiducials can be designed to elicit desirable optical signals that directly indicate any error in the relative pose between the physical and projected virtual objects.Doctor of Philosoph

    Imaging Systems in Assistive Technology

    Get PDF

    Crosstalk in stereoscopic displays

    Get PDF
    Crosstalk is an important image quality attribute of stereoscopic 3D displays. The research presented in this thesis examines the presence, mechanisms, simulation, and reduction of crosstalk for a selection of stereoscopic display technologies. High levels of crosstalk degrade the perceived quality of stereoscopic displays hence it is important to minimise crosstalk. This thesis provides new insights which are critical to a detailed understanding of crosstalk and consequently to the development of effective crosstalk reduction techniques

    Mixed-signal integrated circuits design and validation for automotive electronics applications

    Get PDF
    Automotive electronics is a fast growing market. In a field primarily dominated by mechanical or hydraulic systems, over the past few decades there has been exponential growth in the number of electronic components incorporated into automobiles. Partly thanks to the advance in high voltage smart power processes in nowadays cars is possible to integrate both power/high voltage electronics and analog/digital signal processing circuitry thus allowing to replace a lot of mechanical systems with electro-mechanical or fully electronic ones. High level modeling of complex electronic systems is gaining importance relatively to design space exploration, enabling shorter design and verification cycles, allowing reduced time-to-market. A high level model of a resistor string DAC to evaluate nonlinearities has been developed in MATLAB environment. As a test case for the model, a 10 bit resistive DAC in 0.18um is designed and the results were compared with the traditional transistor level approach. Then we face the analysis and design of a fundamental block: the bandgap voltage reference. Automotive requirements are tough, so the design of the voltage reference includes a pre-regulation part of the battery voltage that allows to enhance overall performances. Moreover an analog integrated driver for an automotive application whose architecture exploits today’s trends of analog-digital integration allowing a greater range of flexibility allowing high configurability and fast prototipization is presented. We covered also the mixed-signal verification approach. In fact, as complexity increases and mixed-signal systems become more and more pervasive, test and verification often tend to be the bottleneck in terms of time effort. A complete flow for mixed-signal verification using VHDL-AMS modeling and Python scripting is presented as an alternative to complex transistor level simulations. Finally conclusions are drawn

    Evaluation of the color image and video processing chain and visual quality management for consumer systems

    Get PDF
    With the advent of novel digital display technologies, color processing is increasingly becoming a key aspect in consumer video applications. Today’s state-of-the-art displays require sophisticated color and image reproduction techniques in order to achieve larger screen size, higher luminance and higher resolution than ever before. However, from color science perspective, there are clearly opportunities for improvement in the color reproduction capabilities of various emerging and conventional display technologies. This research seeks to identify potential areas for improvement in color processing in a video processing chain. As part of this research, various processes involved in a typical video processing chain in consumer video applications were reviewed. Several published color and contrast enhancement algorithms were evaluated, and a novel algorithm was developed to enhance color and contrast in images and videos in an effective and coordinated manner. Further, a psychophysical technique was developed and implemented for performing visual evaluation of color image and consumer video quality. Based on the performance analysis and visual experiments involving various algorithms, guidelines were proposed for the development of an effective color and contrast enhancement method for images and video applications. It is hoped that the knowledge gained from this research will help build a better understanding of color processing and color quality management methods in consumer video

    Tailoring the V-Model for Optics: A Methodology for Optomechatronic Systems

    Get PDF
    The integration of optical technologies into once purely mechatronic systems enables innovative functions, but simultaneously increases the complexity of previous mechatronic system development. Therefore, a process has been elaborated to develop these so-called optomechatronic systems by Knöchelmann at the Institute of Product Development at Leibniz University Hanover, which is based on the V-Model of VDI 2206 and can be applied to various fields of application. For a target-oriented development in a specific product context and for systems with competing main requirements, detailing and adapting the process is recommended. High-resolution lighting systems are one of them, where requirements for high optical efficiency and image quality lead to a conflict of objectives. Focusing on the optics domain, Ley elaborated methods for the preliminary and detailed design of high-resolution lighting systems to address the aforementioned conflict of objectives. This contribution focuses on the integration of Ley’s design methods into Knöchelmann’s process model within the phases of system design and domain-specific design, allowing us to analyze the impact of the system design on the fulfillment of main requirements to achieve an optimal solution of the conflict of objectives. To illustrate this, the integrated process model is described using an example from automotive lighting technology

    Developing a mixed reality assistance system based on projection mapping technology for manual operations at assembly workstations.

    Get PDF
    ABSTRACT Manual tasks play an important role in social sustainable manufacturing enterprises. Commonly, manual operations are used for low volume productions, but are not limited to. Operational models in manufacturing sisters cased of x-to-order paradigms (e.g. assembly-to-order) may require manual operations to speed-up the ramp-up time of new product configuration assemblies. The implications of manual operations in any production line may imply that any manufacturing or assembly process become more susceptible to human errors and therefore translate into delays, defects and/or poor product quality. In this scenario, virtual and augmented realities can offer significant advantages to support the human operator in manual operations. This research work presents the development of a mixed (virtual and augmented) reality assistance system that permits real-time support in manual operations. A review of mixed reality techniques and technologies was conducted, where it was determined to use a projection mapping solution for the proposed assistance system. According to the specific requirements of the demonstration environment, hardware and software components were chosen. The developed mixed reality assistance system was able to guide any user without any prior knowledge through the successful completion of the specific assembly task
    • …
    corecore