During the creation of any concrete floor the concrete needs to be grinded down from it's very rough newly poured form to a more usable floor surface. Concrete floor grinding is very special in that the work area is often immensely large while the height difference on the surface is incredibly small, in-fact the the largest local difference of the surface from a peek to a valley during the grinding process is submillimeter and goes down to micrometer scale. Today's methods for measuring concrete surfaces are very few and all output one dimensional profiles of the surface in very time consuming processes which makes them unsuitable for real-time analysis of the surfaces during the grinding process. Because of this, the effectiveness of the work is dependent on the experience and intuition of the operator of the grinding machine as they have to make the decision of when to move on to the next step in the grinding process. Therefore it is desirable to create a better method for concrete surface measurement that can measure big areas in a short period of time. In this project a structured light method using sinusoidal phase shifting is implemented and evaluated with an easily movable setup that can measure the height of a concrete surface over an area. The method works by encoding the surface with a phase using a projector and analysing how the phase encoding warps when imaging it from an angle. By triangulation this can be made into a height map of the measured area. The end results show that the method is promising for this application and can detect the submillimeter differences. However, more suitable hardware and a more reliable calibration procedure are required to move this prototype towards a more practical measuring device.

No description available.

No description available.

Au cours des dernières années, la capacité de la technologie LiDAR à capturer des informations détaillées sur la structure des forêts a attiré une attention croissante de la part de la communauté des écologues et des forestiers. Le LiDAR terrestre, notamment, apparaît comme un outil prometteur pour recueillir les caractéristiques géométriques des arbres à une précision millimétrique.Cette thèse étudie la reconstruction de surface à partir de nuages de points épars et non structurés, capturés en environnement forestier par un LiDAR terrestre. Nous proposons une suite d’algorithmes dédiés à la reconstruction de modèles d’attributs de placettes forestières : le sol etla structure ligneuse des arbres (i.e. troncs et branches principales). En pratique, nos approches modélisent le problème par des surfaces implicites construites à partir de fonctions à base radiale pour faire face à la forte hétérogénéité spatiale du nuage de points Lidar terrestre. / In recent years, the capacity of LiDAR technology to capture detailed information about forests structure has attracted increasing attention in the field of forest science. In particular, the terrestrial LiDAR arises as a promising tool to retrieve geometrical characteristics of trees at a millimeter level.This thesis studies the surface reconstruction problem from scattered and unorganized point clouds, captured in forested environment by a terrestrial LiDAR. We propose a sequence of algorithms dedicated to the reconstruction of forests plot attributes model: the ground and the woody structure of trees (i.e. the trunk and the main branches). In practice, our approaches model the surface with implicit function build with radial basis functions to manage the homogeneity and handle the noise of the sample data points.

Abstract In this thesis oxidation of a pure and alloyed Cu surface was studied using density functional theory based calculations. The mechanism and energetics behind experimentally observed missing row reconstruction on a pure Cu(100) surface were studied. Examination of the formation of the missing row was approached by studying the profitableness of vacancy formation to the surface at oxygen coverages below and equal to 0.5 ML. However, an ideal surface was in all cases more favourable in energy than vacancy included structures. Therefore an additional Cu atom was added to the simulation cell to promote vacancy formation. A consequence of this on-surface Cu addition was the identifying of a new energetically favoured Cu-O-Cu chain formation. This newly identified structure is a possible transition state in the path from an ideal surface to a reconstructed one. Copper(I)oxide formation through sub-surface adsorption was examined on a reconstructed Cu(100) surface. At low O coverage on-surface adsorption was found to be much more favoured than adsorption on sub-surface sites. However, when coverage increased to 0.75 ML structures with both on-surface and sub-surface adsorbates possessed the lowest energy. Furthermore, the diffusion barriers to the sub-surface adsorption sites were low. Both these facts support the conclusion that the transition from the reconstructed missing row structure to the copper(I)oxide takes place without any large energy effort. The adsorption induced segregation of copper on a Ag/Cu(100) surface was studied by calculating the surface energies of slabs where the silver layer was positioned at different depths with varying O coverage. In addition, the segregation energies were also calculated with two Ag compositions. It was discovered that without oxygen adsorbates silver atoms lying on top of the surface were favoured but the surface segregation probability of Cu increases with increasing O coverage. The same calculation procedure was expanded to study the segregation probability of five additional alloy metals with a Cu surface. Without oxygen present Mg, Al and Zn possess a weak tendency to segregate to the surface, however, V and Cr prefer to stay in the bulk. The addition of oxygen adsorbates on the surface causes the segregation of all the dopants to the top of the surface. With the Al dopant the effect of the surface orientation and the oxygen coverage were also studied. The bonds between adsorbates and the surface were strongest with the densest surface, (111), and weakest with the most opened surface, (110). Furthermore, the enrichment probability was largest in the case of the (111) surface and lowest with the (110) surface. Probability increased with increasing oxygen coverage. / Tiivistelmä Tässä väitöstyössä on tutkittu puhtaan ja seostetun kuparipinnan hapettumista tiheysfunktionaaliteoriaan perustuvilla laskuilla. Kokeellisesti Cu(100) pinnan on havaittu rekonstruoituvan hapen vaikutuksesta. Rekonstruoitumisen aikana ideaalisesta pinnasta irtoaa joka neljäs pintakuparirivi ja muodostuu niin kutsuttu missing row- rakenne. Tämän rakenteen muodostumismekanismia ja muodostumiseen kuluvaa energiaa tutkittiin vertaamalla pintavakansillisten rakenteiden pintaenergioita vastaaviin ideaalipinnan arvoihin vaihtelevalla happipeitolla. Koska ideaalipinta oli kaikilla peittoasteilla energeettisesti suotuisampi kuin vakanssirakenne, yksittäisiä kupariatomeja lisättiin pinnalle stabiloimaan vakanssirakenteita. Kuparilisäyksen seurauksena löydettiin uusi energeettisesti edullinen Cu-O-Cu ketjurakenne. Tämä rakenne on mahdollinen ideaalisen ja rekonstruoituneen pinnan välinen siirtymätila. Kupari(I)oksidin muodostumista pinnanalaisen happiadsorption kautta tutkittiin rekonstruoituneella Cu(100) pinnalla. Pienillä happi-peittoasteilla pinnanpäällisen adsorption havaittiin olevan huomattavasti suotuisampaa kuin pinnanalaisen adsorption. Kuitenkin happi peiton kasvaessa 0,75 ML:iin rakenteet, joissa oli adsorbaatteja sekä pinnan alla että päällä, tulivat muita suotuisimmiksi. Myös lasketut energiavallit hapen diffuusiolle pinnalta pinnan alle olivat hyvin pieniä. Kaikki tulokset viittaavat siihen, että rekonstruoitunut Cu(100) pinta hapettuu helposti kupari(I)oksidiksi. Happiadsorption aikaansaamaa kuparin rikastumista (segregaatio) hopeakupariseosmetallin pinnalle tutkittiin laskemalla vaihtelevilla happipeitoilla pintaenergiat kuparipinnoille, joissa ensimmäinen, toinen ja kolmas kuparikerros oli korvattu hopealla. Myös segregaatioenergiat laskettiin kahdella eri seoskoostumuksella. Saatujen tulosten mukaan ilman happiadsoptiota hopea segregoituu pinnalle, kun taas hapen peittoasteen kasvaessa kupari rikastuu pinnalle. Samaa tutkimustapaa käytettiin myös tarkasteltaessa viiden muun seosmetallin segregaatiotodennäköisyyttä kuparipinnalla. Ilman pintahappea magnesiumilla, alumiinilla ja sinkillä oli heikko taipumus rikastua pinnalle, kun taas vanadium ja kromi pysyivät syvemmällä metallissa. Sen sijaan happea lisättäessä kaikki tutkitut seosmetallit pyrkivät siirtymään kohti pintaa. Myös hapen peiton sekä pintaorientaation vaikutusta segregaatioon tutkittiin hopeakuparipinnalla. Sekä happiadsorbaattien ja pinnan välinen sidos että segregaatiotodennäköisyys oli sitä voimakkaampaa, mitä tiheämmästä pinnasta oli kyse. Segregaatiotodennäköisyys kasvoi pinta-adsorption lisääntyessä.

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No description available.

The main aim of the thesis is the reconstruction of three-dimensional surface from a~set of two-dimensional images. For the implementation of this application the programming language Java and its extension, that allows work with three-dimensional models, were chosen. First, viewing of three-dimensional models of two different file formats was necessary to allow. To create the three-dimensional models, the Marching Cubes algorithm was used. This algorithm is decribed theoretically in the text, description of the implementation and correction of deficiencies follows. Finally, the implementation of the inversion procedure of reconstruction of the three-dimensional surface, which is the extraction of two-dimensional images from the three-dimensional model, is described.

The advancements in robotic perception in the recent years have empowered robots to better execute tasks in various environments. The perception of objects in the robot work space significantly relies on how sensory data is represented. In this context, 3D models of object’s surfaces have been studied as a means to provide useful insights on shape of objects and ultimately enhance robotic perception. This involves several challenges, because sensory data generally presents artifacts, such as noise and incompleteness. To tackle this problem, we employ Gaussian Process Implicit Surface (GPIS), a non-parametric probabilistic reconstruction of object’s surfaces from 3D data points. This thesis investigates different configurations for GPIS, as a means to tackle the extraction of shape information. In our approach we interpret an object’s surface as the level-set of an underlying sparse Gaussian Process (GP) with variational formulation. Results show that the variational formulation for sparse GP enables a reliable approximation to the full GP solution. Experiments are performed on a synthetic and a real sensory data set. We evaluate results by assessing how close the reconstructed surfaces are to the ground-truth correspondences, and how well objects from different categories are clustered based on the obtained representation. Finally we conclude that the proposed solution derives adequate surface representations to reason about object shape and to discriminate objects based on shape information. / Framsteg inom robotperception de senaste åren har resulterat i robotar som är bättre på attutföra uppgifter i olika miljöer. Perception av objekt i robotens arbetsmiljö är beroende avhur sensorisk data representeras. I det här sammanhanget har 3D-modeller av objektytorstuderats för att ge användbar insikt om objektens form och i slutändan bättre robotperception. Detta innebär flera utmaningar, eftersom sensoriska data ofta innehåller artefakter, såsom brus och brist på data. För att hantera detta problem använder vi oss av Gaussian Process Implicit Surface (GPIS), som är en icke-parametrisk probabilistisk rekonstruktion av ett objekts yta utifrån 3D-punkter. Detta examensarbete undersöker olika konfigurationer av GPIS för att på detta sätt kunna extrahera forminformation. I vår metod tolkar vi ett objekts yta som nivåkurvor hos en underliggande gles variational Gaussian Process (GP) modell. Resultat visar att en gles variational GP möjliggör en tillförlitlig approximation av en komplett GP-lösningen. Experiment utförs på ett syntetisk och ett reellt sensorisk dataset. Vi utvärderar resultat genom att bedöma hur nära de rekonstruerade ytorna är till grundtruth- korrespondenser, och hur väl objektkategorier klustras utifrån den erhållna representationen. Slutligen konstaterar vi att den föreslagna lösningen leder till tillräckligt goda representationer av ytor för tolkning av objektens form och för att diskriminera objekt utifrån forminformation.

地面光達系統可以快速獲取大量且高精度之點雲資料，這些點雲資料不但記錄了被掃描物體之三維資訊，還包含其色彩訊息。但因光達點雲資料量過於龐大，若要直接於電腦上展示其三維模型，必須配合有效的資料處理技術，才能迅速且即時地將資料顯示於螢幕上。 我們針對地面光達系統獲取之建物點雲，提出一套處理方法，期盼透過少數關鍵點雲，就足以表示整個建物的模型。研究流程主要分為三階段，首先採用三維網格資料結構，從地面光達系統獲取之建物點雲中，萃取出關鍵點雲，並利用三維不規則三角網建模方式，進行模型建構工作，產生建物大略模型。其次再逐點判斷是否將剩餘之點加入此模型中，持續更新模型細微之部分。最後將點雲中的色彩資訊轉成影像，敷貼在模型表面上，讓整個模型更為逼真。 我們以政大綜合大樓進行實驗，成功地減少大量冗餘的點雲資料，只需要約原始點雲的1％，就足以將綜合大樓模型建構完成。為了達到可以從不同視角即時瀏覽建物模型，我們採用虛擬實境語言(VRML)來描述處理後的三維模型，遠端使用者只需透過一般網頁瀏覽器，即可即時顯示處理過的三維建物模型。 / Ground-based LIDAR system can be used to detect the surface of the buildings on the earth. In general, it produces large amount of high-precision point cloud data. These data include not only the three-dimensional space information, but also the color information. However, the number of point cloud data is huge and is difficult to be displayed efficiently. It’s necessary to use efficient data processing techniques in order to display these point cloud data in real-time. In this research, we construct the three-dimensional building model using the key points selected from a given set of point cloud data. The major works of our scheme consists of three parts. In the first part, we extract the key points from the given point cloud data through the help of a three-dimensional grid. These key points are used to construct a primitive model of the building. Then, we checked all the remaining points and decided whether these points are essential to the final building model. Finally, we transformed the color information into images and then used the transformed images to represent generic surface material of the three-dimensional model of the building. The goal of the final step is to make the model more realistic. In the experiments, we used the twin-tower of our university as our target. We successfully reduced the required data in displaying the building model and only about one percent of the original point cloud data are used in the final model. Hence, one can see the twin-tower from various view points in real-time. In addition, we use VRML to describe our model and the users can browse the results in real-time on internet.