Photogrammetry and laser scanning are two primary methods used for object reconstruction / reverse engineering. But Laser scanners have much higher initial investment compared to photogrammetry method.<div>Currently, in the industry, researchers have been using 3 different softwares for reverse engineering purposes from photogrammetry/laser scanning.</div><div><br></div><div>This thesis is to showcase research work with following points:</div><div>1. Comparison between laser scanner and photogrammetry tools.</div><div>2. Application of photogrammetry in the industry.</div><div>3. Evaluation of photogrammetry tools based on quality of mesh results and comparison with baseline standard of laser-scanner results.</div><div>4. Proposed integrated methodology with photogrammetry tool for reverse engineering within single environment. </div><div>5. Validation of this integrated methodology with case studies.</div><div>6. Parametric study of tool for accuracy and comparison with actual standard models.</div><div><div><br></div></div>

Thesis advisor: Noah P. Snyder / Emerging methods for acquiring high-resolution topographic datasets have the potential to open new opportunities for quantitative geomorphic analysis. This study demonstrates a technique for rapidly obtaining structure from motion (SfM) photogrammetry-derived digital elevation models (DEMs) using aerial photographs acquired with a small unmanned aircraft system (sUAS). In conjunction with collection of aerial imagery, study sites are surveyed with a differential global position system (dGPS)-enabled total station (TPS) for georeferencing and accuracy assessment of sUAS SfM measurements. Results from sUAS SfM surveys of upland river channels in northern New England consistently produce DEMs and orthoimagery with ~1 cm pixel resolution. One-to-one point measurement comparisons demonstrate sUAS SfM systematically measures elevations about 0.16 ±0.23 m higher than TPS equivalents (0.28 m RMSE). Bathymetric (i.e. submerged or subaqueous) sUAS SfM measurements are 0.20 ±0.24 m (0.31 m RMSE) higher than TPS, whereas exposed (subaerial) points are 0.14 ±0.22 m (0.26 m RMSE) higher than TPS. Serial comparison of DEMs obtained before and after a two-year flood event indicates cut bank erosion and point bar deposition of ~0.10 m, consistent with expectations for channel evolution. DEMs acquired with the sUAS SfM are of comparable resolution but a lower cost alternative to those from airborne light detection and ranging (lidar), the current standard for topographic imagery. Furthermore, lidar is not available for much of the United States and sUAS SfM provides an efficient means for expanding coverage of this critical elevation dataset. Due to their utility in municipal, land use, and emergency planning, the demand for high-resolution topographic datasets continues to increase among governments, research institutions, and private sector consulting firms. Terrain analysis using sUAS SfM could therefore be a boon to river management and restoration in northern New England and other regions. / Thesis (MS) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Geology and Geophysics.

Os sistemas de estereofotogrametria digital representam um método não radioativo, seguro, preciso e objetivo para quantificar as dimensões dos tecidos moles faciais. Novos equipamentos têm despontado como alternativa viável nas especialidades que tratam do complexo craniofacial. A estereofotogrametria se destaca pela completa ausência de radiação ionizante, alta velocidade de aquisição, grandes ângulos de visualização, navegação virtual da imagem e possibilidade de integração com outros sistemas de imagens. Quando um novo método é proposto, torna-se necessário avaliar a sua confiabilidade na obtenção de resultados. O objetivo deste estudo foi analisar a repetibilidade intraexaminador em medidas faciais lineares e angulares, em um sistema de estereofotogrametria digital utilizado para avaliação da morfologia facial. A amostra final consistiu em 30 indivíduos adultos brasileiros com idade entre 18 e 45 anos, média de 26,71± 6,53 anos. Vinte e cinco mulheres e cinco homens, saudáveis, sem histórico de traumas ou cirurgias faciais e sem anormalidades congênitas, tiveram pontos de referência marcados em suas faces por um mesmo examinador e foram fotografados em dois momentos, com intervalo de uma semana (T1 e T2), pelo sistema de estereofotogrametria digital Vectra M3® (Canfield Scientific, Fairfield, EUA). Trinta e oito pontos foram demarcados em cada captura. Identificou-se um total de 2280 pontos; 11 medidas foram feitas em cada imagem capturada e 330 medições foram realizadas. As imagens obtidas foram medidas em software próprio do sistema. A análise foi realizada a partir de um conjunto de nove medidas angulares (ângulos nasolabial, mentolabial, convexidade facial, convexidade facial total, nasal, maxilar, mandibular, nasofrontal, maxilofacial, e duas medidas lineares (altura facial média AFAM e altura facial inferior - AFAI), propostas para caracterizar a morfologia facial dos indivíduos da amostra. A repetibilidade intraexaminador na aquisição das medidas foi analisada pela Média Absoluta das diferenças (MAD), Magnitude Relativa do Erro (MRE), Erro Técnico de Medição (ETM), Coeficiente de Correlação Intraclasse (ICC) e análise de Bland-Altman. O teste t para amostras pareadas foi utilizado na identificação de erro sistemático entre T1-T2. O coeficiente de correlação de Pearson foi empregado para verificar a associação entre idade/IMC e o erro nas medições realizadas. Resultados: No cálculo do ETM e da MAD, apenas os ângulos nasolabial (2,17°) e mentolabial (2,88°) apresentaram valores maiores que 2 graus (limite clínico estabelecido para o presente estudo). Para a MRE, 9,1% das medidas foram consideradas moderadas (ângulo maxilofacial), 27,3% foram consideradas boas (ângulo nasal, ângulo maxilar, ângulo mandibular), 45,5% muito boas (ângulo nasolabial, ângulo mentolabial, ângulo nasofrontal, AFAM, AFAI) e 18,2% excelentes (ângulo da convexidade facial, ângulo da convexidade facial total.). Os ângulos nasolabial, mentolabial, convexidade facial, convexidade facial total, maxilofacial e nasofrontal apresentaram valores de ICC (R) classificados como excelentes. O ângulo nasal, e as medidas lineares de AFAI e AFAM tiveram um resultado satisfatório. Não ficou comprovada a relação entre idade/IMC e o erro encontrado entre as medições (diferença absoluta entre T1 e T2). As medidas para AFAM apresentaram um erro sistemático. As medições realizadas foram consideradas precisas dentro dos limites e referências estabelecidas para o presente estudo. Os ângulos nasolabial e mentolabial devem ser interpretados com critério pela variabilidade apresentada. O examinador apresentou boa repetibilidade nas medições realizadas. Os resultados obtidos no presente estudo acrescentam confiabilidade ao uso da estereofotogrametria digital na antropometria facial. Os parâmetros de precisão adequados a cada situação, em clínica ou em pesquisa, devem ser previamente estabelecidos. / Digital stereophotogrammetry systems represent a non-radioactive, safe, and accurate method to quantify the facial soft tissues dimensions. New equipment has emerged as viable alternative in the specialties that deal with the craniofacial complex. Stereophotogrammetry system has been highlighted by the complete absence of ionizing radiation, high-speed acquisition, large viewing angles, virtual image navigation and possibility of integration with others imaging systems. When a new method is proposed, it is necessary to assess its reliability in achieving results. The aim of this study was to analyze the intra-examiner repeatability on linear and angular facial measurements into a digital stereophotogrammetry system used to assess facial morphology. The final sample consisted of 30 Brazilian adults aged between 18 and 45 years, average of 26.71±6,53 years. Five men and twenty-five women, healthy, with no history of trauma or previous facial surgeries and without congenital abnormalities, had landmarks labeled on their faces by the same rater and were photographed in two stages (T1-T2), with an interval of one week, at stereophotogrammetry system digital Vectra M3® (Canfield Scientific, Fairfield, NJ). Thirty-eight points were labeled in each capture. 2280 points were identified; 11 distances were measured in each image, giving a total of 330 measurements. The images were measured by a dedicated software system. The analysis was performed from a set of nine angular measurements (nasolabial, mentolabial, facial convexity, full facial convexity, nasal, maxillary, mandibular, nasofrontal, maxillofacial angles, and two linear measurements (middle facial height - AFAM and lower facial height AFAI). Precision and intra-rater repeatability in the measurements acquisition were evaluated by the Mean Absolute Difference (MAD) Relative Error Magnitude (REM), Technical Error of Measurements (TEM), intra-class correlation coefficient (ICC) and Bland-Altman analysis. Test t for paired samples was used in the systematic error identification between T1-T2. The Pearson correlation coefficient was used to verify the association between age / BMI and measurement errors. Results: to the estimated TEM and MAD only nasolabial angles (2.17°), mentolabial (2.88°) had higher values than 2.0 degrees (clinical limit for this study). For MRE, 9.1% of the measures were considered moderate (maxillofacial angle), 27.3% were considered good (nasal angle, maxillary angle, mandibular angle), 45.5% very good (nasolabial angle, mentolabial angle, nasofrontal angle, AFAM, AFAI) and 18.2% excellent (facial convexity, full facial convexity.). The nasolabial, mentolabial, facial convexity, total facial convexity, maxillofacial and nasofrontal angles showed R values rated as excellent. The nasal angle, and the linear measurements of AFAI and AFAM had a satisfactory outcome. It was not proven the relation between age / body mass index and the error (absolute difference between T1 and T2). Measures to AFAM showed a systematic error. Conclusion: The measurements were considered accurate within the limits and references established for this study. The examiner showed good repeatability in identifying landmarks. The results presented on this study add reliability to the Digital stereophotogrammetry in clinical and research activities, provided there are previously established adequate precision parameters.

Thesis (Ph. D.)--Ohio State University, 2004. / Includes bibliographical references (p. 156-166).

Due to the Columbia Space Shuttle Accident of February 2003, the Columbia Accident Investigation Board determined the need for an on-orbit inspection system for the Thermal Protection System that accurately determines damage depth to 0.25". NASA contracted the Spacecraft Technology Center in College Station, Texas, for a proof-of-concept photogrammetric system. This system involves a high quality digital camera placed on the International Space Station, capable of taking high fidelity images of the orbiter as it rotates through the Rendezvous Pitch Maneuver. Due to the pitch rotation, the images are tilted at different angles. The tilt causes the damage to exhibit parallax between multiple images. The tilted images are therefore registered to the near-vertical images using visually striking features on the undamaged surface of the Thermal Protection System that appear in multiple images taken at different tilt angles. The images become relatively oriented after registration, and features in one image are ensured to lie on the epipolar line in the other images. Features that do not lie on the undamaged surface, however, are shifted in the tilted images. These pixels are matched to the near-vertical image using a sliding-window area-matching approach. The windows are matched using a least-squares error method. The change in location for a pixel in a tilted image from its expected location on the undamaged surface is called the pixel disparity. This disparity is linearly scaled using the tilt angle and the pixel sampling to determine the depth of the damage at that pixel location. The algorithm is tested on a set of damaged tiles at the Johnson Space Center in Houston and the photogrammetric damage depth is then compared to a set of truth data provided by NASA. The photogrammetric method shows promise, with the 0.25" error limit being exceeded in only a few pixel locations. Once the camera properties are fully known from calibration, this systematic error should be reduced.

An orthophoto map is made from a combination of different geospatial datasets such as relief, imagery, powerlines and annotation. These data sets are usually generated by different divisions within national mapping agencies. Often, when an orthophoto mapping project is to be undertaken, other functions within and outside the system, are actuated. Examples of such functions include; photogrammetric scanning, digital elevation capturing, aerial triangulation, ancillary data and imagery acquisition and map compilation. This research is underpinned by the hypothesis that different components that supply data required for generating orthophoto maps do not work as a coherent whole. This behaviour impacts negatively on the production of orthophoto maps as well as the quality of the end product and can have spill over effects on service delivery. In this research, systems analysis, client satisfaction survey and SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis are used as a collective set of tools to analyze an orthophoto mapping system (OMS) in order to mitigate this unwanted behaviour. The case of orthophoto map production at the Chief Directorate of Surveys and Mapping (CDSM) in South Africa is used. First, systems analysis, which uses the Data Flow Diagram (DFD) technique, is employed to depict the system‘s data stores, processes and data flows. This approach helps to show how the current system works thereby assisting to pin point areas that require improvement. After presenting the system ‘s processes, data stores and data flows, a client satisfaction survey, built on the criteria of; accuracy, completeness, correctness and accessibility of geospatial datasets, is conducted on one of the data stores – the Topographical Information System (TIS) database. Finally, a SWOT analysis is then done on the whole OMS to evaluate the internal and external environment under which the current system operates in. Gaps are identified and recommendations suggested. Although in this case, the recommendations are built based on the CDSM case study, it is believed they can benefit other OMS’s in similar operating conditions elsewhere. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

No description available.

Thesis (Ph.D.)--Tufts University, 2001. / Adviser: Chris Rogers. Submitted to the Dept. of Mechanical Engineering. Includes bibliographical references (leaves 140-146). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (MScIng)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 172-180).