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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Calibration of CCD Camera for Underwater Laser Scanning System

Hwaung, Tien-Chen 04 February 2002 (has links)
To estimate the correct dimension of the target on the underwater, we can use CCD camera and cast laser light strip onto the target, and then observe the displacement of laser light to get the dimension. Since the laser light will show on different situation, it's due to the surface of the target is not smooth. When we get the image from CCD camera, we need to calibrate the displacement of the laser light and return to the actual dimension of the target on the underwater. We know the optical distortion and non-linearity of the CCD camera will influence to get the correct image, also the location of camera is. That's the reason we need to calibrate the camera first. It was a mathematical way to explain the calibration of CCD camera non-linearity before. On this subject, we lay vertical and horizontal grid lines of 50 mm span on an acrylic plate. These grid lines are same as the longitudes and latitudes of the map. We estimate the target with the pair of interpolated longitude and latitude same as to be used to estimate the location of the point in the world coordinate system. And choose some targets with different size and form to use to verify the approach. By the way, we also test if there is any influence for the clear of water. The results indicate the error is under 3 \% when we catch the image on the underwater by a calibrated CCD camera.
172

Development of a Mobile Tomographic Gamma Camera Based on Ectomography - Cardiotom

Persson, Mikael January 2001 (has links)
<p>Successful treatment of myocardial infarction requires anearly and accurate diagnosis. Recent studies have shown thatacute myocardial scintigraphy has a high predictive value forprognosis of myocardial events. Three dimensional (3D)perfusion data obtained with SPECT are however very rare in theemergency department (ED).</p><p>We have developed a mobile tomographic system for myocardialscintigraphy, which can be used in the ED. The objectives ofthe studies presented were:</p><p>    To develop software and hardware for a mobile tomographicgamma camera system: the Cardiotom</p><p>    To demonstrate that a mobile tomographic system can beused in a clinical situation</p><p>    To evaluate the limitations of Ectomography when usingfiltered back projection for reconstruction</p><p>    To develop a method of reconstruction that compensatesfor the incomplete data acquisition associated with theacquisition geometry of Ectomography</p><p>Three prototypes of a mobile tomographic gamma camera systemhave been designed and built at the Division of MedicalEngineering, which all have been used in a clinical setting.The systems are based on Ectomography, a limited view anglemethod, also developed by us. Instead of rotating the entiregamma camera detector around the patient as in SPECT, a slanthole collimator is rotated in front of a stationary detector.Since short imaging times are important in the ED and the heartonly occupies a small area of the detector, system sensitivityhas been increased by dividing the collimator into segmentswith different projection directions. In myocardial imaging, 4segments are used and within 10 minutes from the start ofacquisition, reconstructed short axis view sections areavailable for interpretation.</p><p>Using the Cardiotom in an experimental animal study, weverified that the system could be used to quantify myocardialarea at risk and final infarct size. This conclusion was madefrom a comparison of images obtained from the Cardiotom andpathological staining of the myocardium, analysedpost-mortem.</p><p>Inherent limitations of Ectomography were evaluated withboth phantom studies and computer simulated data, reconstructedusing filtered back-projection Results show that moderatedeviation from optimal position of the detector with respect tothe myocardium will have little or no influence on thediagnostic information when assessed from short axis sectionimages and polar tomograms. However, long axis section imagesappear elongated when reconstructed using filteredback-projection.</p><p>We have shown that this elongation distortion can besuppressed using iterative reconstructions techniques, and wehave implemented such an algorithm, called three-dimensionalTotal Variation Expectation Maximisation (3DTV-EM). Resultswere that elongation distortion was reduced and depthresolution improved. The reconstruction technique was alsoevaluated for SPECT reconstruction and was found to decreasethe noise in reconstructed images, when compared to thetwo-dimensional TV-EM algorithm. Noise pattern were also foundto be more uniform for the 3DTV-EM algorithm compared totwo-dimensional TV-EM.</p><p>In conclusion, we have shown that the Cardiotom may beuseful in a clinical acute setting, providing valuablediagnostic information. Rapid positioning is possible, sincemoderate deviation from optimal positioning will cause few orno artefacts. Image quality can be improved if iterativetechniques are used for image reconstruction instead offiltered back-projection.</p><p><b>Keywords</b>: acute studies, myocardial infarction,scintigraphy, mobile gamma camera, tomography.</p>
173

Synchronization of a Multi Camera System

Vibeck, Alexander January 2015 (has links)
In a synchronized multi camera system it is imperative that the synchronization error between the different cameras is as close to zero as possible and the jitter of the presumed frame rate is as small as possible. It is even more important when these systems are used in an autonomous vehicle trying to sense its surroundings. We would never hand over the control to a autonomous vehicle if we couldn't trust the data it is using for moving around. The purpose of this thesis was to build a synchronization setup for a multi camera system using state of the art RayTrix digital cameras that will be used in the iQMatic project involving autonomous heavy duty vehicles. The iQMatic project is a collaboration between several Swedish industrial partners and universities. There was also software development for the multi camera system involved. Different synchronization techniques were implemented and then analysed against the system requirements. The two techniques were hardware trigger i.e. external trigger using a microcontroller, and software trigger using the API from the digital cameras. Experiments were conducted by testing the different trigger modes with the developed multi camera software. The conclusions show that the hardware trigger is preferable in this particular system by showing more stability and better statistics against the system requirements than the software trigger. But the thesis also show that additional experiments are needed for a more accurate analysis. / iQMatic
174

Occupant Detection System

Ohlson, Frida, Al-Mosawi, Nadim January 2015 (has links)
The purpose of the ODS (Occupant Detection System) project is to develop a car safety camera system that is able to discriminate human occupants in order to activate safety features depending on the human size. In order to discriminate the size of an occupant anthropometric measurements need to be performed. The aim of this study was to investigate the possibility of anthropometric measurements of human height and weight with a Kinect for Windows v2 sensor for discrimination of different occupants inside a vehicle. The goal was to find valid anthropometric methods for determination of human height and weight from landmarks on the upper body, then test if it is possible to perform these methods with the Kinect for Windows v2 sensor. The execution of this study was performed as a literature study with anthropometric tests on ATD-dummies (anthropomorphic test device) and on human test subjects. Measurements were performed first physically and then with the Kinect v2 sensor to obtain data in form of distance of 8 regions of the body. Three tests were performed, first on dummies, second was a pilot study and last the measurement study. The result revealed that it is hard to estimate human weight from body landmarks due to lack of information, therefor no tests were performed in this area. For height the result showed that the most valid methods were the measurements on arm span and ulna, both on physical measurements and with the camera. The conclusion is that it is possible estimating height from body landmarks but the positioning of the camera needs to be change in order for the measurements to be more accurate. This study has contributed to a greater understanding of measurement technology, automotive safety and anthropometric measurements.
175

A star tracker design for CubeSats

McBryde, Christopher Ryan 12 June 2012 (has links)
This research outlines a low-cost, low-power, arc-minute accurate star tracker that is designed for use on a CubeSat. The device is being developed at the University of Texas at Austin for use on two different 3-unit CubeSat missions. The hardware consists of commercial off-the-shelf parts designed for use in industrial machine vision systems and employs a 1024x768 grey-scale charge coupled device (CCD) sensor. The software includes the three standard steps in star tracking: centroiding, star identification, and attitude determination. Centroiding algorithms were developed in-house. The star identification code was adapted from the voting method developed by Kolomenkin, et al. Attitude determination was performed using Markley's singular value decomposition method. The star tracker was then tested with internal simulated star-fields. The resulting accuracy was less than an arcminute. It was concluded that this system is a viable option for CubeSats looking to improve their attitude determination. On-orbit demonstration of the system is planned when the star tracker flies on the planned CubeSat missions in 2013 or later. Further testing with external simulated star fields and night sky tests are also planned. / text
176

Time-resolved X-ray diffraction studies of poly (ethylene terephthalate) during uniaxial and biaxial deformation

Bingham, Suzanne J. January 2000 (has links)
No description available.
177

Gerald Finzi's Requiem da Camera (op. 3b, 1924), with Particular Emphasis on Editorial Problems in its Third Movement

Cook, Casey January 2013 (has links)
English composer Gerald Finzi's (1901-1956) early life was plagued by the deaths of close friends and family, and the beginning of the first world war. Before his eighteenth birthday, Finzi lost his three brothers, his father and his beloved composition teacher. To mourn these deaths and perhaps as a reaction to the first world war, Finzi began to compose his Requiem da Camera (op. 3b, 1924). Finzi completed three movements of this four-movement work during his lifetime, and left sketches for the completion of the unfinished third movement. Beginning in 1984, Philip Thomas, with the blessing of the Finzi family and the Finzi Trust, began examining the extant sketches in an attempt to complete the unfinished third movement. Thomas completed and published his edition of the Requiem da Camera in 1992. After a careful examination of this completion, a number of editorial questions were raised. This document was created to address these questions. It sets out historical parameters to provide context for Finzi's original composition, goes on to describe the development of liturgical and non-liturgical requiem composition, and discusses the development of British non-liturgical requiem (and requiem-like) compositions in the twentieth century. Thomas's completed third movement is compared to Finzi's source material. Four major areas of discrepancy are presented and examined to bring the movement closer to Finzi's original compositional intent. The document concludes with a new completion of the third movement. It combines the work of Finzi and Thomas, along with information gleaned in the process of creating this document, the remainder of the original Finzi composition, and other of Finzi's compositions with similar qualities from this era.
178

Defining Ray Sets for the Analysis of Lenslet-Based Optical Systems Including Plenoptic Cameras and Shack-Hartmann Wavefront Sensors

Moore, Lori Briggs January 2014 (has links)
Plenoptic cameras and Shack-Hartmann wavefront sensors are lenslet-based optical systems that do not form a conventional image. The addition of a lens array into these systems allows for the aberrations generated by the combination of the object and the optical components located prior to the lens array to be measured or corrected with post-processing. This dissertation provides a ray selection method to determine the rays that pass through each lenslet in a lenslet-based system. This first-order, ray trace method is developed for any lenslet-based system with a well-defined fore optic, where in this dissertation the fore optic is all of the optical components located prior to the lens array. For example, in a plenoptic camera the fore optic is a standard camera lens. Because a lens array at any location after the exit pupil of the fore optic is considered in this analysis, it is applicable to both plenoptic cameras and Shack-Hartmann wavefront sensors. Only a generic, unaberrated fore optic is considered, but this dissertation establishes a framework for considering the effect of an aberrated fore optic in lenslet-based systems. The rays from the fore optic that pass through a lenslet placed at any location after the fore optic are determined. This collection of rays is reduced to three rays that describe the entire lenslet ray set. The lenslet ray set is determined at the object, image, and pupil planes of the fore optic. The consideration of the apertures that define the lenslet ray set for an on-axis lenslet leads to three classes of lenslet-based systems. Vignetting of the lenslet rays is considered for off-axis lenslets. Finally, the lenslet ray set is normalized into terms similar to the field and aperture vector used to describe the aberrated wavefront of the fore optic. The analysis in this dissertation is complementary to other first-order models that have been developed for a specific plenoptic camera layout or Shack-Hartmann wavefront sensor application. This general analysis determines the location where the rays of each lenslet pass through the fore optic establishing a framework to consider the effect of an aberrated fore optic in a future analysis.
179

A Cluster based Free Viewpoint Video System using Region-tree based Scene Reconstruction

Lei, Cheng Unknown Date
No description available.
180

Estimation des paramètres biophysiques des cultures agricoles par télédétection aéroportée

El Khadji, Nadia January 2008 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

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