As-built documentation is an essential set of records, consisting of construction drawings, specifications and equipment location, which are kept for facility management purposes. These documents are constantly being created and modified throughout the life of a project. This process is usually manual and fraught with errors, which inhibits reliable decision making. Technological advancements have made it possible to generate 3D models to assess as-built conditions for construction monitoring purposes, such as verifying conformance to baseline project schedules and contract specifications. For this purpose, 3D point clouds are widely generated using laser scanners. However, this approach has limitations in the construction industry due to the expensive and fragile equipment, lack of portability and need of trained operators. This study aims at investigating an alternate technology to generate as-built 3D point clouds using photos taken using handheld digital cameras, compare them against the original as-built 3D models, and check for accuracy of the modeling process. This analysis can aid in more reliable and effective decision making due to its cost effectiveness and ease of use, particularly in heavy infrastructure projects which are continually undergoing rehabilitation work. To achieve these objectives, a set of guidelines are developed for taking photographs that enable effective generation of 3D point clouds using off-the-shelf software packages. The accuracy of the modeling process is investigated using the results of the as-built 3D point cloud modeling of a 2000 feet under construction bridge in southern United States. Finally, the range of tolerance and deviation of element dimensions is determined by comparing the photo based model to the actual as-built model (developed using 2D drawings). Furthermore, to compare point clouds of laser scanning and photogrammetry, a laser scan and an image based survey of an exterior wall of a university building was also done. Results show that this technology in its present state is not suitable for modeling infrastructure projects, however technological developments can enable this to be an efficient way to extract measurements of inaccessible objects for progress monitoring purposes and the models can also be stored for future dimension takeoffs for decision making and asset management purposes. / text

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The term Gossamer is used to describe ultra-lightweight spacecraft structures that solve the aerospace challenge of obtaining maximum performance while reducing the launch costs of the spacecraft. Gossamer structures are extremely compliant, which complicates control design and ground testing in full scale. One approach is to design and construct smaller test articles and verify their computational models experimentally, so that similar computational models can be used to predict the dynamic performance of full-scale structures. Though measurement of both in-plane and out-of-plane displacements is required to characterize the dynamic response of the surface of these structures, this thesis lays the groundwork for dynamic measurement of the in-plane component. The measurement of thin films must be performed using non-contacting sensors because any contacting sensor would change the dynamics of the structure. Moreover, the thin films dealt with in this work are coated with either gold or aluminum for special applications making the film optically smooth and therefore requiring a surface pattern. A Krypton Fluoride excimer laser system was selected to fabricate patterns on thin-film mirror test articles. Parameters required for pattern fabrication were investigated. Effects of the pattern on the thin-film dynamics were studied using finite element analysis. Photogrammetry was used to study the static in-plane displacement of the thin-film mirror. This was performed to determine the feasibility of the photogrammetric approach for future dynamic tests. It was concluded that photogrammetry could be used efficiently to quantify dynamic in-plane displacement with high-resolution cameras and sub-pixel target marking.

Gossamer membranes are large, ultra light weight, highly flexible thin films. They have been proposed for use as elements in systems such as solar sails and optical apertures, whose large areas require a low-mass material that can be launched in a compact package and then deployed to operational configuration upon reaching orbit. Many of the proposed applications require that the film possess a flat, wrinkle-free surface. Surface wrinkle configuration is determined, in part, by the method used to support the film. One configuration that has not been studied in detail involves the formation of vertical wrinkles oriented along the direction of a tensile force applied at the upper and lower horizontal film supports. An experiment was designed to allow known forces to be applied to a 9 inch by 9 inch square sample of film supported at its upper and lower boundaries. Four films 7.6 m and 12.7 m thick samples of Kapton (polymide), and 12.2 m and 23.4 m thick samples of Mylar were loaded at levels of applied tensile force ranging from 1.446 to 4.388 N. The out-of-plane surface contours that resulted were measured using close-range photogrammetry, a non-contact, optical measurement technique. Experimental results indicate that both wrinkle wavelength and amplitude decrease as a function of applied force magnitude. These trends matched those obtained using numerical techniques, which also showed that lateral border strain, not measured during the experiment, may be a more important factor in determining surface wrinkle configuration. After presentation of the results, the photogrammetry technique is further considered as a tool for use in the manufacturing industry, in similar close-range applications, for the measurement of both dimensions and displacements.

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Thesis (M.S.)--Northwest Missouri State University, 2006. / The full text of the thesis is included in the pdf file. Title from title screen of full text.pdf file (viewed on January 25, 2008) Includes bibliographical references.

Thesis (M.S.)--Oregon State College, 1958. / Typescript. Includes bibliographical references (leaves 91-95). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1992. / Includes mounted photographs. Typescript (photocopy). Includes bibliographical references (leaves 133-136). Also available on the World Wide Web.