Experimental study is an important methodology for ocean engineering research. However, measuring any physical parameters in the field involves the instrumentation to overcome a wide range of problems, such as robustness to the severe environment, limitation of power supply and data storage, and also simplicity of operation. Taking seabed profile or bedform measurement as an example, conductivity point gauge or ultra-sound non-contact profiler is usually adopted. Limited by the time needed per sampling, these approaches are costly in operation if dense grid points are required to describe the variation of a long transect. In addition to this drawback, the surface will be disturbed after conductivity-based contact probing. We propose using an off-the-shelf, non-metric CCD camera along with a simple calibration methodology as an alternative to carry out the measurement. As the semiconductor technology advances drastically, nowadays high quality CCD cameras are available with inexpensive prices. Recently, CCD camera emerges as a convenient input sensor for many applications. However, generally it requires a delicate optical and geometrical calibration of the camera before it can be used to carry out 2D or 3D measurement of the target. The optical parameters are focal length, distortion of lens, optical axis offset, CCD array linearity and etc; and geometrical parameters are position and orientation of the CCD camera. Some of these parameters are sensitive to the setup of the system, and a re-calibration is needed whenever the system is disassembled or moved. We propose using a template on which grid points of known locations are used to construct several sub-mappings between measurement coordinate system and image pixel coordinate system. This simple procedure is effective to meet the accuracy requirement for several applications. In this work, this idea is adopted and verified in three different experiments: An underwater laser line scanner, a cross-section wave tank bedform profiling and Particle Imaging Velocimetry.

Several recent high profile incidents involving law enforcement officers have resulted in the death of a citizen. In some of these cases, the use of deadly force by police was ruled as justified only to learn later that one or more officers were not truthful about what occurred. These incidents have called into question law enforcement's legitimacy and created a demand for greater transparency by equipping officers with body-worn cameras. Body cameras can act as independent, reliable witnesses with no bias or agenda. Federal, state, and local governments have pledged millions of taxpayer dollars to implement body-worn camera programs in police departments across the world, but research has revealed mixed results on the effectiveness of body-worn cameras. Effectiveness can be defined as a reduction in use of force incidents, citizen complaints, and offender and officer injuries during apprehension situations. Data were obtained from a large police department in the Southeastern United States that began using body-worn cameras in January 2015. A purposeful sample of 3 years of data before body cameras were introduced and 3 years of data after body cameras were introduced was analyzed using an interrupted time-series design. There was a statistically significant increase in use of force incidents and offender injuries during apprehension situations. There was no statistically significant change in citizen complaints or officer injuries. This research can assist police executives and program evaluators with providing expectations and setting goals for body camera programs.

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MSc (Dentistry), Faculty of Health Sciences, University of the Witwatersrand, 2009 / Problem. One of the sources of inaccuracy in utilising the CEREC Chairside CAD/CAM system has been the difficulty of accurately positioning the intraoral camera relative to the path of insertion of the preparation and restoration. The degree of inaccuracy produced by variations in the angulation of the camera relative to the path of insertion is not known. Purpose. The purpose of this study was to first review the literature and history of CAD/CAM in dentistry, and the CEREC Chairside System in particular, and then to determine the errors that may result from changes in angulation of the camera in three dimensions. Further, to design a device which would help stabilise the camera to eliminate such errors. Method and Materials. A prefabricated Aesthetic Base Gold (ABG) Model was used and mounted on an articulator in order to simulate changes in angulation of each of the three dimensional axes which cause variations in roll, pitch, and yaw in the positioning of the camera. Images were captured for angle variations of 0°, 1°; 3°, 5°, 10°, 15° and 20° using the CEREC software on a crown preparation for tooth 24. The same software was used to make measurements on the resulting images to determine the mesio-distal, bucco-lingual orientation and the occlusal, internal shoulder and external shoulder dimensions. In addition, a quality assessment was carried out to observe any shadows, surface texture changes, margin discrepancies and ability to automatically complete the restoration with ease and accuracy. An intraoral stabilising device was designed that could be placed intraorally using polyvinyl siloxane putty. The ABG model was positioned to simulate quadrants 2 and 4 on crown iv preparation for tooth 24. Time to set up and place the device was recorded, and a Visual Analogue Scale was used to determine ease of use. Results. Difficulties were encountered in measurements of images where there was an angle deviation of greater than 5º, and so it was only possible to analyse the four angles of 0, 1, 3, and 5º. A three-way ANOVA revealed expected significant differences between the different measurements (as they are measuring different things) but there were no other significant differences. Thus neither the four different angles nor the three different axes had any influence on the readings. There was also consistency across the measurements, for every combination of the levels of the three factors (angle, measurement and axis). The stabilising device proved quick and easy to set up and place the silicone putty (less than 20 seconds) and the average VAS score for using the device improved by 25.3% when using the device in the lower, and by 36.4% when using the device in the upper arch. Conclusions. The angle of the camera relative to the path of insertion of the restoration should not exceed 3° for changes in Pitch, or 5° for changes in Roll and Yaw of the camera. The stability device designed during this study proved to be more convenient and accurate for data capture as it decreased the time of search and reduced both the internal and external factors which interfere with data capture.

Thesis (M.S.V.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1984. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Includes bibliographical references. / The camera obscura has allowed artists, scientists, and philosophers to view the world as a flat image. Two - dimensional renditions of visual reality seem to be more manageable and easier to grasp than reality itself. A Lexicon for Camera Obscura is a survey of facts and lore about the author's use-of camera obscura as a metaphorical vehicle to comment about reality. / by Robert David Rosinsky. / M.S.V.S.