Includes bibliographical references (p. 70-74).

Thesis (Ph. D.)--University of Florida, 1982. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 95-97).

Dans cette thèse, on s’intéresse à l’application du domaine de la vision par ordinateur à la vélocimétrie de surface des rivières. Les hydrauliciens utilisent déjà plusieurs routines de traitement d’images pour traiter des vidéos de rivières. Le but ultime est d’estimer la vitesse surfacique d’un cours d’eau par une méthode sans contact. Cela permet aux chercheurs d’éviter les risques liés au jaugeage intrusif des rivières, notamment en période de crue. Dans ce but, deux enjeux sont à prendre en compte. Tout d’abord, le mouvement apparent de la rivière dans l’espace image doit être estimé. Ensuite, ce mouvement, estimé en pixels par unité de temps, doit être transformé en une vitesse réelle exprimée en mètres par seconde par exemple. Jusqu’au présent, les méthodes de vélocimétrie par images imposent quelques contraintes sur les séquences pour qu’elles soient exploitables (notamment une caméra fixe et le besoin de la présence physique des équipes hydrauliques au site de jaugeage avant ou après l’événement). Dans cette thèse, on vise à élargir ce périmètre en incluant les vidéos prises par des amateurs (c’est à dire de paramètres inconnus, et avec un mouvement potentiel de la caméra) tout en présentant de meilleures solutions pour les enjeux précédemment mentionnés. / This thesis is an application of computer vision findings to river velocimetry research. Hydraulic research scientists already use various image processing techniques to process image sequences of rivers. The ultimate goal is to estimate free surface velocity of rivers remotely. As such, many risks related to intrusive river gauging techniques could be avoided. Towards this goal, there are two major issues need be addressed. Firstly, the motion of the river in image space need to be estimated. The second issue is related to how to transform this image velocity to real world velocity. Until recently, imagebased velocimetry methods impose many requirements on images and still need considerable amount of field work to be able to estimate rivers velocity with good accuracy. We extend the perimeter of this field by including amateur videos of rivers and we provide better solutions for the aforementioned issues. We propose a motion estimation model that is based on the so-called optical flow, which is a well developed method for rigid motion estimation in image sequences. Contrary to conventional techniques used before, optical flow formulation is flexible enough to incorporate physics equations that govern rivers motion. Our optical flow is based on the scalar transport equation and is augmented with a weighted diffusion term to compensate for small scale (non-captured) contributions. Additionally, since there is no ground truth data for such type of image sequences, we present a new evaluation method to assess the results. It is based on trajectory reconstruction of few Lagrangian particles of interest and a direct comparison against their manually-reconstructed trajectories. The new motion estimation technique outperformed traditional methods in image space. Finally, we propose a specialized geometric modeling of river sites that allows complete and accurate passage from 2D velocity to world velocity, under mild assumptions. This modeling considerably reduces the field work needed before to deploy Ground Reference Points (GRPs). We proceed to show the results of two case studies in which world velocity is estimated from raw videos.

Measurement of the dynamics of flexible structures is difficult because the motion is often complex and the structures are not well suited to the attachment of sensors. As a result, non-contact optical systems are used. However, optical systems produce large amounts of data which make their use in real-time measurement difficult. Conventional computers are not well suited to the processing requirements associated with data from optical systems. In this thesis, algorithms and architectures to reduce the data bandwidth of an optical measurement system are investigated. Simulations of the ability of the algorithms to find a target on a linear-array charge-coupled device (CCD) camera are performed. The running maximum algorithm provides the best accuracy and speed and therefore is recommended. A real-time architecture to implement the running maximum algorithm is developed. The architecture allows the optical system to operate at 9700 frames/second. Experimental results from a prototype system show very good accuracy for both static and dynamic measurements. / Master of Science

A particle counting instrument, the Coherent Optical Particle Spectrometer (COPS) has been developed for measuring particles in aerosol systems. It optically counts and sizes single particles one at a time as they pass through an optically defined inspection region so particle size distributions can be directly measured. COPS uses the coherent nature of light available in a laser beam to measure the phase shift in the scattered light, which is fundamentally different from previous intensity based techniques. The Van-Cittert-Zernike theorem shows that scattered light from small particles will be coherent if viewed upon at the focal point of a gathering lens. Optical homodyne detection can then be used to measure the extent of the phase shift due to the particle. Scattering mechanisms can relate the phase shift to particle diameter so particle size can be determined. An optical inspection region is given by the resolution limited blur spot diameter and depth of focus of the gathering lens. Particles scattering outside this zone will not contribute to measured phase signals. Calculations show that COPS can count in concentrations of 10('9) particles per cubic centimeter with 5% coincidence error. Mie scattering calculations, coupled with homodyne theory, predict a minimum detectable particle diameter ranging from 0.03 to 0.3 micrometers, depending on optical configuration. Theory shows that small, strongly absorbing particles impart a much larger phase shift than refractive particles so a lower detection limit is predicted for particles such as soot and silicon. Particles above one micrometer show classic resonance typical of Mie calculations. An experimental COPS system verified the predicted results from the model. Resolution of particle size ranged from 25 to 60 percent of particle diameter. Preliminary experiments showed that COPS has in situ sampling possibilities and will work for liquid systems as well. Coherent detection of scattered light shows promise for in situ measurement of submicrometer aerosols in high particle laden streams with maximum sensitivity for strongly absorbing particles.

No description available.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Bibliography: leaves 141-142. / by David Adams Garlow. / M.S.

Structural organization refers to the particular ordering of scatterers. Probing structural organization by imaging polarized spectral scatter provides insight into the composition of a medium, and can aid in remote sensing, the identification of tissue pathologies, and material characterization and differentiation. The vector nature of polarized light enables it to interact with optical anisotropies within a medium, while the spectral aspect of polarization is sensitive to small-scale structure. However, many polarization studies have limitations, as they provide qualitative image analysis, incomplete anisotropy information, or both. The ability to image the effects of anisotropy and small-scale structure at multiple wavelengths is key for parameterizing structural organization. The Stokes/Mueller formalism is a framework that quantifies a medium's complete spectral polarization response, and allows for the parameterization of structural organization. Additionally, advances in liquid crystal (LC) technology have resulted in new polarimetric devices. These computer-controlled devices impart spectral polarization effects on the millisecond timescale with no mechanically moving hardware, providing the ability for making rapid polarimetric measurements. This dissertation describes a methodology for revealing structural organization by exploiting the Stokes/Mueller formalism and by utilizing measurements from a spectral imaging polarimeter constructed from variable retardance LC devices, such as liquid crystal variable retarders (LCVRs) and a liquid crystal tunable filter (LCTF). The methodology includes developing the system, the Stokes/Mueller model, and all of the procedures, calibrations, and data interpretation. Developing the system also consists of component and system calibration, a system sensitivity and performance analysis, and finally test measurements for system validation. The final validation measurement is made on a mineral sample for inferring structural organization.

<p>The aim was to develop, manufacture and evaluate diffractive lenses, or diffractive optical elements (DOE), for use in correlation with a camera to add perspective in pictures. The application is a miniaturized submarine developed in order to perform distant exploration and analysis in harsh and narrow environments. The idea is to project a laser pattern upon the observed structure and thereby add geometrical information to pictures acquired with an onboard CMOS camera. The design of the DOE-structures was simulated using the optimal rotational angle method (ORA). A set of prototype DOEs were realized using a series of microelectromechanical system (MEMS) processes, including photolithography, deposition and deep reactive-ion etching (DRIE). The projected patterns produced by the manufactured DOEs were found to agree with the simulated patterns except for the case where the DOE feature size was too small for the available process technology to handle. A post-processing software solution was developed to extract information from the pictures, called Laser Camera Measurement (LCM). The software returns the x, y and z coordinate of each laser spot in a picture and provides the ability to measure a live video stream from the camera. The accuracy of the measurement is dependent of the distance to the object. Some of the patterns showed very promising results, giving a 3-D resolution of ~0.6 cm, in each dot, at a distance of 1 m from the camera. Lengths can be resolved up til 3 m distance from the submarine.</p> / <p>Tillämpningen finns i en miniatyriserad ubåt framtagen för utforskning och analys av svåråtkomliga och trånga håligheter. Målet var att designa, tillverka och utvärdera en diffraktiv lins (DOE) för användning tillsammans med en kamera för att skapa perspektiv i bilder. Idén var att projicera ett lasermönster på objektet och därmed lägga till geometrisk information till bilderna tagna med CMOS kameran. Utformningen av DOE-strukturerna simulerades med the optimal rotational angle method (ORA). En uppsättning av prototyp DOE-linser tillverkades med hjälp av en serie mikrostrukturteknikprocesser, bland annat fotolitografi, deponering och plasmaetsning. Mönster projicerade med de tillverkade DOE-linserna stämde väl överens med önskade mönster, med undantag för de DOEs där strukturstorleken underskred processens begränsningar. En programvara, kallad Laser Camera Measurement (LCM), utvecklades för att extrahera information från bilderna. Programvaran returnerar x, y, och z koordinaterna för varje laserpunkt i en bild och ger möjlighet att mäta i en kontinuerlig videoström från kameran.  Mätosäkerheten är beroende av avståndet till objektet. Vissa mönster gav mycket lovande resultat, med en 3-D upplösning på ~0.6 cm, i varje punkt, på ett avstånd av 1 m från kameran. Längder kan upplösas upp till 3 m från kameran där ett så kallat far-field uppstår.</p> / DADU

The aim was to develop, manufacture and evaluate diffractive lenses, or diffractive optical elements (DOE), for use in correlation with a camera to add perspective in pictures. The application is a miniaturized submarine developed in order to perform distant exploration and analysis in harsh and narrow environments. The idea is to project a laser pattern upon the observed structure and thereby add geometrical information to pictures acquired with an onboard CMOS camera. The design of the DOE-structures was simulated using the optimal rotational angle method (ORA). A set of prototype DOEs were realized using a series of microelectromechanical system (MEMS) processes, including photolithography, deposition and deep reactive-ion etching (DRIE). The projected patterns produced by the manufactured DOEs were found to agree with the simulated patterns except for the case where the DOE feature size was too small for the available process technology to handle. A post-processing software solution was developed to extract information from the pictures, called Laser Camera Measurement (LCM). The software returns the x, y and z coordinate of each laser spot in a picture and provides the ability to measure a live video stream from the camera. The accuracy of the measurement is dependent of the distance to the object. Some of the patterns showed very promising results, giving a 3-D resolution of ~0.6 cm, in each dot, at a distance of 1 m from the camera. Lengths can be resolved up til 3 m distance from the submarine. / Tillämpningen finns i en miniatyriserad ubåt framtagen för utforskning och analys av svåråtkomliga och trånga håligheter. Målet var att designa, tillverka och utvärdera en diffraktiv lins (DOE) för användning tillsammans med en kamera för att skapa perspektiv i bilder. Idén var att projicera ett lasermönster på objektet och därmed lägga till geometrisk information till bilderna tagna med CMOS kameran. Utformningen av DOE-strukturerna simulerades med the optimal rotational angle method (ORA). En uppsättning av prototyp DOE-linser tillverkades med hjälp av en serie mikrostrukturteknikprocesser, bland annat fotolitografi, deponering och plasmaetsning. Mönster projicerade med de tillverkade DOE-linserna stämde väl överens med önskade mönster, med undantag för de DOEs där strukturstorleken underskred processens begränsningar. En programvara, kallad Laser Camera Measurement (LCM), utvecklades för att extrahera information från bilderna. Programvaran returnerar x, y, och z koordinaterna för varje laserpunkt i en bild och ger möjlighet att mäta i en kontinuerlig videoström från kameran.  Mätosäkerheten är beroende av avståndet till objektet. Vissa mönster gav mycket lovande resultat, med en 3-D upplösning på ~0.6 cm, i varje punkt, på ett avstånd av 1 m från kameran. Längder kan upplösas upp till 3 m från kameran där ett så kallat far-field uppstår. / DADU