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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.
1

Multi-modal registration of maxillodental CBCT and photogrammetry data over time

Bolandzadeh-Fasaie, Niousha 06 1900 (has links)
This thesis aims at introducing a methodology for clinical evaluation of orthodontic treatments using three-dimensional dento-maxillofacial images. Since complementary information is achieved by integrating multiple modalities, cone-beam computed tomography (CBCT) and stereophotogrammetry technologies are used to develop a methodology for tracking bone and facial skin variations over time. Our proposed methodology consists of a two-phase registration procedure. In the first phase, the multimodal images are registered using an extrinsic landmark-based registration followed by a robust Iterative Closest Points (ICP) method. In the second phase, by utilizing specific anatomical landmarks, single modal images of the skull and the mandible are registered over time using an intrinsic landmark-based registration method followed by the robust ICP algorithm. The results of registrations show that the signed error distribution of both mandible and skull registrations follow a normal distribution while all the errors fall within the CBCT precision range.
2

Multi-modal registration of maxillodental CBCT and photogrammetry data over time

Bolandzadeh-Fasaie, Niousha Unknown Date
No description available.
3

Chronic lateral instability of the ankle joint : natural course, pathophysiology and steroradiographic evaluation of conservative and surgical treatment

Löfvenberg, Richard January 1994 (has links)
Chronic lateral instability of the ankle (CLI), defined as frequent sprains and recurrent giving way, difficulty in walking and running on uneven surface, is often connected with pain and swollen ankles. It occurs in 10 to 20 percent after acute ankle injuries. Mechanical instability of the talocrural and subtalar joint, peroneal weakness and impaired proprioception has been suggested as etiological factors. Aim. To investigate the natural course in conservatively treated patients with CLI. To assess the mechanical stability in patients with CLI by measuring the three dimensional motions in the talus, the fibula and the calcaneus in relation to the tibia during different testing procedures pre- and postoperatively. To determine if CLI is associated with proprioceptive deficiency. Patients and Methods. This Thesis includes 127 ankles in 78 patients (30 women, 48 men) with CLI. Thirty-seven patients were followed up 20 years after their first contact with the orthopaedic department because of CLI. Forty-six ankles were evaluated radiographically and the result was compared with a gender- and age - matched control-material. The neuromuscular response to a sudden angular displacement of the ankles was studied in 15 ankles in 13 patients using EMG. Thirty-six patients entered a prospective study using roentgen stereophotogrammetric analysis (RSA) in which the ankles were tested at manual adduction, adduction with predetermined torque, with and without external support and at drawer tests (40 N and 160N). Twenty-seven patients were followed five years postoperatively. Result. After 20 years 22 patients, conservatively treated still suffered from instability of the ankle and ten had recurrent giving way symptoms even on plane surface. Six ankles in the patient group and four in the control group displayed osteoarthritic changes Prolonged ipsilateral reaction time (m. per. long, and m. tib. ant.) was found in patients with CLI indicating proprioceptive insufficiency. Increased talar adduction and a tendency toward increased total translation of the talar center was found in ankles with CLI. Concomitant fibular rotations and translations were found but with no conclusive deviation in the ankles with symptoms. The talo-calcaneal adduction reached the same level in the patient and control groups regardless of symptoms. External support (ankle brace) increased the talar stability. The use of predetermined torque and constrained testing procedure did not add information compared with the manual test Twenty-five patients graded the result as excellent or good five years after lateral ligament reconstruction. Talar stability (decreased adduction and translation) was increased two years postoperatively and was improved or remained the same at five years without comprising the range of motion. Conclusion. In more than half the cases symptoms of CLI did not resolve spontaneously. Minor degenerative changes was found after twenty years, but not to a greater extent than in a control group. CLI was associated with proprioceptive insufficiency and talocrural but not subtalar instability. Increased ankle stability can be obtained by the use of an ankle brace and by an anatomical ligament reconstruction. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1994</p> / digitalisering@umu
4

Nyttoanalys av volym- och fragmenteringsmätning : För en bättre uppskattning av järnhalt vid lastning i Kiruna skivrasgruva

Tonvall, Tobias January 2017 (has links)
I LKAB:s gruva i Kiirunavaara i Malmfälten tillämpas brytningsmetoden skivrasbrytning, som går ut påatt driva ortar in i malmkroppen, från dem borra uppåtgående hål i malmkroppen, spränga och sedanlasta ut malmen, som med gravitationens hjälp rasar ner i orten.Ett mål för detta examensarbete är att undersöka fragmenterings- och volymmätningens potentiellaeffekt på det dataunderlag som ligger till grund för beslutsfattande i produktionslastningen. Ett målär också att undersöka fragmenteringens effekt på skrymdensiteten vid skivrasbrytning.Analysarbetet baseras på data från ett markörförsök som utfördes i Kiirunavaaragruvan 2013/2014.För att verifiera tillförlitligheten hos det mätdata som ligger till grund för analysen, har metodernaför mätning av massa och skopvolym testats. En känd volym stenmaterial med en givenfragmentering vägdes i en lastmaskin och fotograferades på samma vis som under markörförsöken.Resultatet för volymmätningen visade på en överskattning som minskade med ökande volym och varmindre än 5 % för volymer över 4 m3. Resultatet för viktmätningen indikerade dock ett konsekventfel på över 20 %, vilket dock berodde på felaktig eller inte genomförd kalibrering av just denlastmaskinen.Volymanalysen visade att beräkningsmetoden som LKABs mjukvara för beräkning av järnhalt (WOLIS)använder sig av har utrymme för förbättringar. Efter att de föreslagna ändringarna genomförts,kvarstår dock en överskattning på 14 % av järnutbytet för WOLIS jämfört med volymmätning. Vidjämförelse av järnhalterna vs. utlastningsgrad, så visar WOLIS och volymmätningar liknande trendermed vissa skillnader, och dessa bedöms inte vara stora nog för att påverka lastningsbeslut.Den första hypotesen inför fragmenteringsanalysen var att det skulle finnas ett samband mellanblandad fragmentering och skrymdensitet för skopor som bedömts innehålla endast malm; detta pågrund av att mindre fragment teoretiskt fyller ut hålrummen mellan större fragment. Något sådantsamband kunde inte styrkas utifrån analysen. Den andra hypotesen var att det finns ett sambandmellan grövre fragmentering och lägre skrymdensitet för de analyserade skoporna (både malm- ochgråbergsskopor), och bekräftades av analysen. Detta stämmer väl överens med erfarenheten avbrytningsmetoden, där grövre fragmenterat material ofta inte kommer från malmkroppen, ochdärmed inte är uppsprängt som material i sprängkransarna.Volym- eller fragmenteringsmätning i produktionen rekommenderas inte av detta arbete. Iställetföreslås förändringar av beräkningsmodellen i WOLIS. En systematisk överskattning av malmutbytetkvarstår dock. Överskattningen utreds inte i detta arbete utan föreslås som fortsatt arbete,tillsammans med att se över produktionens rutiner för att motverka förekomsten av överlastning ochutebliven eller felaktig skopvågskalibrering vid service. / In the LKAB-mine in Kiirunavaara in the ore fields of Norrbotten, the mining method Sublevel Cavingis used. Drifts are developed transverse through the orebody from which blast rings are drilledupwards. The ore is blasted while the hangingwall progressively fails and fills the void. By means ofgravity flow both materials may be transported to the drawpoint from which mucking is carried out.One objective of the thesis is to examine the potential effect of volume measurement on the datawhich serves as basis for decision-making in the mucking operation. Another objective is toinvestigate the effect of fragmentation on bulk density. The analysis is based on data acquired from agravity flow study executed in the Kiirunavaara Mine in 2013/2014.In order to verify the reliability of the measured data, which is the basis of the analysis, the methodsfor measurement of bucket mass and bucket volume were tested. A known amount of crushed stoneof a certain size fraction was weighted in an LHD bucket and photographed in the same manner asduring the marker trials. The volume results showed an over-estimation of less than 5 % for bucketswith volumes larger than 4 m3.The error decreased with increasing volume. The weight, however,was consistently off by over 20 %, which could be attributed to improper or overlooked calibration ofthat particular LHD.The volume analysis showed that there is room for improvement in the calculation methods appliedin the software used by LKAB to calculate iron content (WOLIS). With the proposed changeshowever, a 14 %-over-estimation of iron recovery remains for WOLIS compared to the volumemeasureddata. When comparing iron content and extraction rate, the WOLIS-based curves showsimilar trends with some differences. They are not, however, expected to be enough to have bearingon mucking decisions.The first hypothesis for the fragmentation analysis is that a correlation exists betweeninhomogeneous fragmentation and bulk density for buckets containing exclusively ore. Theoretically,smaller fragments should fill the void between larger fragments. Such a correlation could not befound though. The second hypothesis is that coarser fragmentation is correlated to lower bulkdensity (for both ore- and waste rock buckets), which was also confirmed by the analysis. This is inaccordance with the experiences of the mining method, as coarsely fragmented material oftenderives from the hangingwall, and thereby isn’t as finely blasted as the actual blasted ore.A consequent volume measurement is not recommended in the thesis. Instead, changes in thecalculation model of the present measurement system are proposed. A systematic over-estimationof the ore production remains, however. It is suggested to investigate this in a further study. Inaddition it should be paid attention to the current procedures in mucking in particular, the observedoverloading and possible calibration errors.
5

Vyhledávání korespondence ve stereosnímcích tváří / Stereoscopic Face Images Matching

Klaudíny, Martin Unknown Date (has links)
This thesis is dedicated to the problem of 3D face capture. A majority of current face capture systems exploits a pattern projection. The goal of thesis was to develop the 3D face capture system based on the passive stereo photogrammetry. The high-resolution images of a face are captured by one pair of the calibrated digital still cameras. The image pre-processing consists of the removal of lens distortion, rectification of image pair and face extraction. The stereo image matching is accentuated. Three different approaches to the stereo correspondence search are presented - the local technique, the global technique using a graph cut and the hybrid technique merging previous two. At last, the 3D model is reconstructed according to the found correspondence. The results show that the high-quality 3D face models can be obtained despite traditional difficulties with matching pattern-free face images. Also it is possible to keep the computational demands on the acceptable level, although the high-resolution images are processed.
6

Constru??o de mosaicos georreferenciados usando imagens a?reas de pequeno formato

Cordeiro, Natal Henrique 04 August 2008 (has links)
Made available in DSpace on 2014-12-17T15:47:49Z (GMT). No. of bitstreams: 1 NatalHC.pdf: 2764921 bytes, checksum: 846252ab05f6de9b65d1cf7bbe1aba09 (MD5) Previous issue date: 2008-08-04 / In this work we propose a technique that uses uncontrolled small format aerial images, or SFAI, and stereohotogrammetry techniques to construct georeferenced mosaics. Images are obtained using a simple digital camera coupled with a radio controlled (RC) helicopter. Techniques for removing common distortions are applied and the relative orientation of the models are recovered using projective geometry. Ground truth points are used to get absolute orientation, plus a de&#64257;nition of scale and a coordinate system which relates image measures to the ground. The mosaic is read into a GIS system, providing useful information to different types of users, such as researchers, governmental agencies, employees, &#64257;shermen and tourism enterprises. Results are reported, illustrating the applicability of the system. The main contribution is the generation of georeferenced mosaics using SFAIs, which have not yet broadly explored in cartography projects. The proposed architecture presents a viable and much less expensive solution, when compared to systems using controlled pictures / No presente trabalho, descrevemos uma metodologia para a constru??o de mosaicos georreferenciados a partir de imagens a?reas de pequeno formato, ou SFAI, consideradas n?o controladas. T?cnicas de Est?reo-Fotogrametria e de Vis?o Computacional s?o aplicadas para auxiliarem em resultados de qualidade e con&#64257;abilidade. As imagens s?o obtidas atrav?s de uma c?mera digital comum acoplada a um helic?ptero aeromodelo. T?cnicas para eliminar distor??es comuns s?o aplicadas e a orienta??o relativa dos modelos ? realizada baseada na geometria projetiva. Pontos reais do terreno s?o usados para executar a orienta??o absoluta, al?m de uma de&#64257;ni??o de escala e de um sistema de coordenadas que relaciona a imagem medida no terreno. O mosaico ser? manipulado em um SIG, fornecendo informa??o ?til a diferentes tipos de usu?rios, tais como pesquisadores, institui??es governamentais, pescadores e empresas de turismo. Resultados s?o gerados, ilustrando a aplicabilidade do sistema. A principal contribui??o ? a gera??o de mosaicos georreferenciados usando imagens a?reas de pequeno formato, o que tem sido pouqu?ssimo explorado em projetos de cartogra&#64257;a. A arquitetura proposta apresenta uma solu??o vi?vel e bem barata quando comparada com sistemas que utilizam imagens controladas

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