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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

Improvement of Structured Light Systems Using Computer Vision Techniques

Yaan Zhang (8781872) 02 May 2020 (has links)
<div> <div> <div> <p>In this thesis work, we propose computer vision techniques for 3D reconstruction and object height measurement using a single camera and multi-laser emitters, which have an intersection on the projected image plane. Time-division and color division methods are first investigated for our structured light system. Although the color division method offers better accuracy for object height measurement, it requires the laser emitters equipped with different color lights. Furthermore, the color division method is sensitive to light exposure in the measurement environment. Next, a new multi-level random sample consensus (MLRANSAC) algorithm has been developed. The proposed MLRANSAC method not only offers high accuracy for object height measurement but also eliminates the requirement for the laser emitters with different colors. Our experiment results have validated the effectiveness of the MLRANSAC algorithm. </p> </div> </div> </div>
2

Single view metrology applied for dynamic control of sink height for children

LIU, HUI January 2011 (has links)
ABSTRACT In our modern society, the design and implementation of intelligent equipments for autonomous physical services become more and more important. In line with this, the proposed Intelligent Vision Agent System, IVAS, is able to automatically detect and identify a target for a specific task by surveying human activities space. One of IVAS’ applications can be the adjustment of sink height for different height of people. Usually, the sink is fixed in one place, however, the height of sink could be too high to use for children. It becomes a real problem and may bring much of inconvenience and insecurity for the little boys and girls. The equipment for dynamical adjustment of sink height is rare in today’s society. The most common sink height adjustments are of two types. The first way is to place two sinks, one for adult and one for a kid individually. The second way is to use a spring device to adjust the height of sink. But, the both solutions have some limitations. The disadvantage of first method is that it takes too much space, and not all bathrooms can accommodate two sinks at the same time. The weakness of second way is a need to manually adjust the height of sink. In order to achieve an optimal design of adjustable sink high, the author uses a camera fixed on wall connected to an intelligent agent controlling suitable actuators. The camera captures a photo of the person who comes to the sink. The height of person can be estimated from the image. Furthermore, one makes use of this height value to find the suitable sink height for the user. Finally, the sink is descending or ascending by the lifting columns to adjust it to the different height of people. In this thesis, the author has implemented a method, which estimates the height of person from a single image. This technique is based on the single view metrology. Keywords: Sink, Height Measurement, Vision, Single View Metrology
3

Mätosäkerheter vid trigonometrisk höjdmätning : En jämförelse mellan ett avvägningsinstrument och en multistation

Nilsson, Mimmi January 2016 (has links)
Avvägning är den traditionella metoden för höjdmätning, medan trigonometrisk höjdmätningunderlättar vid höjdmätning på längre avstånd och vid kuperad terräng. Syftet med studien varatt undersöka mätosäkerheten vid trigonometrisk höjdmätning. Detta genom en jämförelsemed traditionell höjdmätning som utförts med ett finavvägningsinstrument samt hur mångahelsatser som krävs för att erhålla resultat med låg mätosäkerhet för trigonometriskhöjdmätning. Kravet som ställdes var 2 mm√L, där L är avvägningstågets längd i km.Mätningarna har genomförts i två tunnlar varav i den ena var markytan plan och i den andralutade marken 1 m på 10 m (1/10). Höjdfixarna monterades i bergväggen ungefär var tiondemeter och höjdbestämdes med avvägningsinstrument, DNA03, för att erhålla sanna höjder förhöjdfixarna. Därefter mättes höjdfixarna in genom trigonometrisk höjdmätning i helsatsermed multistationen MS50. Höjder erhållna med trigonometrisk höjdmätning beräknades ochnätutjämnades i Svensk byggnadsgeodesi (SBG) Geo 15 för att sedan kunna jämföra medhöjd som erhållits med avvägningsinstrument. Signifikanstest beräknades för varje mätningför att avgöra om mätningarna var av samma population.Slutningsfelet för samtliga avvägningståg ligger inom toleransen och tillförlitligheten förhöjdbestämningen är hög. Vid höjdbestämning med trigonometrisk höjdmätning kan intesamma låga mätosäkerhet som med avvägningsinstrument förväntas, men inte långt ifrån.Med trigonometrisk höjdmätning, utfört med MS50, för distanser mellan 10-100 m kan enmätosäkerhet runt 0,5-1,5 mm förväntas vid mätning i två helsatser. Signifikanstestet visadeatt fler mätningar var inom konfidensintervallet 95 % när två kända höjder användes iberäkningarna i stället för en känd höjd. Vid mätning med totalstation kan lägremätosäkerheter för trigonometrisk höjdmätning förväntas än 0,5-1,5 mm på 10-100 m. / The aim of the thesis was to determine the uncertainty of trigonometric height measurementin comparison by traditional height measurement performed with a digital level. Levelling isthe traditional method of height measurement while the trigonometric height measurementfacilitates height measurement at longer distances and in terrain. The uncertainty of thetrigonometric height measurement has been investigated as well as how many rounds ofmeasurements are sufficient for measurements between 10-100 m.The measurements were carried out in two tunnels where in one the ground was plane and inthe other it is grade was 1/10. Height fixes were mounted about every 10 meters in the rockwall and height determined with a levelling instrument, DNA03, to obtain true elevations onheight fixes. Thereafter, the height of the fixes were measured through trigonometric heightmeasurement in one, two, three and four rounds of measurements with a multi station, MS50.Elevation data was calculated and levelling net adjusted in Svensk byggnadsgeodesi (SBG)Geo to then compare the height data from the trigonometric height measurement with thelevelled height obtained by levelling instruments. Significance tests were calculated for themeasurement to determine if the measurements are of the same population.Connection error of all leveling was within tolerance which shows that the reliability of theheight determination is high. The height determination by trigonometric height measurementcan not be of the same low uncertainty that is expected with levelling, but not far from it.With trigonometric height measurement, carried out with MS50, for distances between 10-100m can an uncertainty of 0.5-1.5 mm be expected when two rounds of measurements are used.Significance test shows that more measurements are within the confidence interval 95% whentwo known heights are used in the calculations, instead of one known height.
4

Zvýšení bezpečnosti přistávacího manévru / Increasing landing maneuver safety

Zedníček, Václav January 2016 (has links)
Diploma thesis concerns methodology, safety and common pilot’s mistakes in phase of landing. It concludes statistics and landing accident reports of airplanes with maximum take-off weight of 5700 kg. It also concerns method of height estimating above ground. It describes usable systems for landing aid and suggests its own technical solutions for safety improvements based on poll.

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