Shape analysis of railway ballast stones : curvature-based calculation of particle angularity

Particle shape analysis is conducted, to compare two types of railway ballast: Calcite and Kieselkalk. Focus lies on the characterisation of particle angularity using 3D scanner data. In the literature, angularity is often characterised using 2D data, as these types of data are easier to collect. 3D scanner data contain a vast amount of information (e.g. curvatures) which can be used for shape analysis and angularity characterisation. Literature approaches that use 3D data are often not thoroughly tested, due to a lack of test cases. In this work, two new curvature-based angularity indices are introduced and compared to one from the literature. Analytical test bodies with shapes ranging from spherical towards cubic are used for a first plausibility test. Then, 3D scans of ballast stones are compared to artificially rounded meshes. Only one out of three evaluated angularity indices seem to be suited to characterise angularity correctly in all of the above tests: the newly introduced scaled Willmore energy. A complete shape analysis of the scanned ballast stones is conducted and no difference between the two types of ballast can be seen regarding form, angularity, roughness, sphericity or convexity index. These findings of shape analysis are set in the context of previous works, where experimental results and DEM simulations of uniaxial compression tests and direct shear tests were presented for the same ballast types

Hihnan päällä toimivan optisen 3D-granulometriajärjestelmän mekaanisten oheislaitteiden kehitys

This thesis presents the process of designing the mechanical structure for a commercial particle size analyzer of granular material based on on-line 3D optical granulometry technology. The analyzer can be used to monitor and increase the performance of various processes within the mining, mineral, and metal industry (MMMI), particularly grinding processes that utilize autogenous and semi-autogenous grinding mills. The analysis system contributes to the evolution of the MMMI in a more energy efficient direction, resulting in a decreased ecological footprint of the industry as well as financial benefits for the operators. The design work done for this thesis contributes to a product development project by Outotec, a technology company specializing in the MMMI. Prior work within the project included a detailed business analysis and software development. A systematic methodology to carry out the design work was derived from the field of engineering design literature. The methodology is based on decomposition of the design problem into smaller subproblems. By finding solutions for each subproblem individually, an overall conceptual solution is produced. This methodology was used to create explicit engineering parameters and a conceptual solution for the mechanical structure of the product, based on the prior work done on the product development project. The conceptual solution was then defined further into a complete mechanical design and a functional prototype. The prototype was tested and evaluated based on the engineering parameters. Based on the results, a second iteration of the design was created, improving on the initial design. Based on objective evaluation of the second design iteration, the design meets all the criteria set for the product development project and can be taken to market. However, the evaluation and further iteration of the design will continue after product launch based on customer feedback and product performance.Tämä diplomityö esittelee optiseen 3D granulometriateknologiaan perustuvan kaupallisen partikkelikokoanalysaattorin mekaanisen suunnitteluprosessin. Analysaattorin pääasiallinen käyttötarkoitus liittyy kaivosteollisuuden erinäisten prosessien monitorointiin ja ohjaukseen. Ensisijainen käyttökohde on autogeenisiä ja semiautogeenisiä myllyjä hyödyntävien jauhatusprosessien syöttömateriaalin monitorointi. Suunniteltu laitteisto edistää kaivosteollisuuden kehittymistä energiatehokkaampaan suuntaan ja siten toimialan aiheuttaman ekologisen jalanjäljen pienentämistä. Laitteen tarkoitus on myös tuottaa taloudellista hyötyä sekä kaivosteollisuuden operaattoreille että laitteen toimittajalle. Tämän diplomityö on tehty kaivosalalla toimivan teknologiayhtiön, Outotecin, toimeksiannosta ja edesauttaa erästä yhtiön tuotekehitysprojektia. Suunnittelutyö toteutettiin tuotekehitykseen liittyvästä kirjallisuudesta löydettyjä systemaattisia menetelmiä hyödyntäen. Käytetty suunnittelumetodiikka perustuu suunnitteluongelman jakamiseen pienempiin osatekijöihin. Suunnitteluongelma ratkaistaan löytämällä kullekin osatekijälle toimiva ratkaisu. Kyseiseen metodiikkaan sekä tuotekehitysprojektin aiempiin työpanoksiin perustuen tuotteelle luotiin yksikäsitteiset suunnitteluparametrit sekä mekaaninen konsepti. Konseptin pohjalta suunniteltiin tuotteen mekaaninen rakenne ja rakennettiin toimiva prototyyppi, joka testattiin aiemmin luotujen suunnitteluparametrien perusteella. Tulosten perusteella tuotteesta suunniteltiin toinen versio, jossa korjattiin testauksessa havaittuja puutteita. Toisen tuoteversion objektiivisen arvioinnin perusteella suunnittelutyön tavoitteisiin on päästy. Tämän arvion perusteella tuote täyttää kaikki sille asetetut kriteerit ja se voidaan viedä markkinoille. Tuotteen suorituskyvyn arviointi ja rakenteen iterointi jatkuu kuitenkin vielä markkinoille viennin jälkeen

2D and 3D computer vision analysis of gaze, gender and age

Human-Computer Interaction (HCI) has been an active research area for over four decades. Research studies and commercial designs in this area have been largely facilitated by the visual modality which brings diversified functionality and improved usability to HCI interfaces by employing various computer vision techniques. This thesis explores a number of facial cues, such as gender, age and gaze, by performing 2D and 3D based computer vision analysis. The ultimate aim is to create a natural HCI strategy that can fulfil user expectations, augment user satisfaction and enrich user experience by understanding user characteristics and behaviours. To this end, salient features have been extracted and analysed from 2D and 3D face representations; 3D reconstruction algorithms and their compatible real-world imaging systems have been investigated; case study HCI systems have been designed to demonstrate the reliability, robustness, and applicability of the proposed method.More specifically, an unsupervised approach has been proposed to localise eye centres in images and videos accurately and efficiently. This is achieved by utilisation of two types of geometric features and eye models, complemented by an iris radius constraint and a selective oriented gradient filter specifically tailored to this modular scheme. This approach resolves challenges such as interfering facial edges, undesirable illumination conditions, head poses, and the presence of facial accessories and makeup. Tested on 3 publicly available databases (the BioID database, the GI4E database and the extended Yale Face Database b), and a self-collected database, this method outperforms all the methods in comparison and thus proves to be highly accurate and robust. Based on this approach, a gaze gesture recognition algorithm has been designed to increase the interactivity of HCI systems by encoding eye saccades into a communication channel similar to the role of hand gestures. As well as analysing eye/gaze data that represent user behaviours and reveal user intentions, this thesis also investigates the automatic recognition of user demographics such as gender and age. The Fisher Vector encoding algorithm is employed to construct visual vocabularies as salient features for gender and age classification. Algorithm evaluations on three publicly available databases (the FERET database, the LFW database and the FRCVv2 database) demonstrate the superior performance of the proposed method in both laboratory and unconstrained environments. In order to achieve enhanced robustness, a two-source photometric stereo method has been introduced to recover surface normals such that more invariant 3D facia features become available that can further boost classification accuracy and robustness. A 2D+3D imaging system has been designed for construction of a self-collected dataset including 2D and 3D facial data. Experiments show that utilisation of 3D facial features can increase gender classification rate by up to 6% (based on the self-collected dataset), and can increase age classification rate by up to 12% (based on the Photoface database). Finally, two case study HCI systems, a gaze gesture based map browser and a directed advertising billboard, have been designed by adopting all the proposed algorithms as well as the fully compatible imaging system. Benefits from the proposed algorithms naturally ensure that the case study systems can possess high robustness to head pose variation and illumination variation; and can achieve excellent real-time performance. Overall, the proposed HCI strategy enabled by reliably recognised facial cues can serve to spawn a wide array of innovative systems and to bring HCI to a more natural and intelligent state

Machine vision in measurement and control of mineral concentration process

This thesis considers machine vision in the context of the mining, mineral and metal industry (MMMI). Even though MMMI might be seen as a rather conservative industry branch, in many cases it is not. One motivation for constant research and development is the large amount of ore processed on a yearly basis, which means that even a slight improvement in performance can lead to substantial economical benefits. Another point, related more closely to the thesis, is that the development in camera and information technology has enabled the integration of machine vision based applications into many different industry branches, MMMI being one of them. Machine vision and its utilization in measurement and control of a modern flotation plant is studied in detail. The research was started in the late 90's with the development of an image analysis platform for flotation froths, which was later extended to cover multiple flotation cells. The resulting image analysis based variables were studied and new results regarding their usefulness both in single and multi-camera settings were obtained. The most important variables are shown to the plant operators and used in closed loop control. Furthermore, an image history database and a tool for its utilization were created, as well as a new type of froth level measurement technique introduced. The research done with the image analysis of flotation froths provided strong evidence of the importance of the froth colour as an indicator of grade. This motivated further studies carried out with a spectrophotometer, which is a more accurate instrument for colour measurements. As a result, a new type of on-line measurement technique was created to be used as a supplement to existing X-Ray fluorescence (XRF) analyzers to reduce their typical sampling interval of 10-20 minutes to a virtually continuous measurement. Another field of research presented is the particle size distribution analysis of crushed ore from a moving conveyor belt in a contact-free manner, for which two new measurement techniques are presented. This information, when measured already in the mine, can be used in the flotation plant to gain better grinding results, and geologists can use it in mine planning

A mathematical morphology approach to image based 3D particle shape analysis

Angularity is a critically important property in terms of the performance of natural particulate materials. It is also one of the most difficult to measure objectively using traditional methods. Here we present an innovative and efficient approach to the determination of particle angularity using image analysis. The direct use of three-dimensional data offers a more robust solution than the two-dimensional methods proposed previously. The algorithm is based on the application of mathematical morphological techniques to range imagery, and effectively simulates the natural wear processes by which rock particles become rounded. The analysis of simulated volume loss is used to provide a valuable measure of angularity that is geometrically commensurate with the traditional definitions. Experimental data obtained using real particle samples are presented and results correlated with existing methods in order to demonstrate the validity of the new approach. The implementation of technologies such as these has the potential to offer significant process optimisation and environmental benefits to the producers of aggregates and their composites. The technique is theoretically extendable to the quantification of surface texture

Forum Bildverarbeitung

Bildverarbeitung spielt in vielen Bereichen der Technik zur schnellen und berührungslosen Datenerfassung eine Schlüsselrolle und hat sich in unterschiedlichen Anwendungen einen unverzichtbaren Platz erobert. Von besonderer Bedeutung ist dabei eine zielführende Verarbeitung der erfassten Bildsignale. Das "Forum Bildverarbeitung" greift diese hochaktuelle Entwicklung sowohl hinsichtlich der theoretischen Grundlagen, Beschreibungsansätze und Werkzeuge als auch relevanter Anwendungen auf