Mesh Addition Based on the Depth Image (MABDI)

Many robotic applications utilize a detailed map of the world and the algorithm used to produce such a map must take into consideration real-world constraints such as computational and memory costs. Traditional mesh-based environmental mapping algorithms receive data from the sensor, create a mesh surface from the data, and then append the surface to a growing global mesh. These algorithms do not provide a computationally efficient mechanism for reducing redundancies in the global mesh. MABDI is able to leverage the knowledge contained in the global mesh to find the difference between what we expect our sensor to see and what the sensor is actually seeing. This difference between expected and actual allows MABDI to classify the data from the sensor as either data from a novel part of the environment or data from a part of the environment we have already seen before. Using only the novel data, a surface is created and appended to the global mesh. MABDI\u27s algorithmic design identifies redundant information and removes it before it is added to the global mesh. This reduces the amount of memory needed to represent the mesh and also lessens the computational needs to generate mesh elements from the data

Ricostruzione Di Oggetti Tridimensionali Basata su Sistemi Fuzzy a Partire da Punti Acquisiti Mediante Scanner

In questo lavoro di tesi di laurea specialistica viene affrontato il problema della ricostruzione di oggetti tridimensionali utilizzando sistemi a regole Fuzzy a partire da nuvole di punti disorganizzati acquisite mediante scanner. Per poter trattare scansioni composte da milioni di punti è stato necessario introdurre il concetto di inferenza fuzzy con troncamento, che riduce considerevolmente sia l'occupazione di memoria che il tempo di calcolo

Voxel octree intersection based 3D scanning

Recent developments in the field of three dimensional (3D) printing have resulted in widely available low-cost 3D printers. These printers require 3D models, which are traditionally created in 3D modeling software or are created from 3D scans of existing objects. To be printable, these models must exhibit the property of being watertight. In this thesis, a technique is developed, which, in combination with a custom built low-cost 3D scanner, produces watertight 3D models. Models produced by this technique - the voxel octree intersection technique - do not require any additional processing prior to 3D printing. Results from using this technique with the custom built scanner are examined, and along with the effects of changing various parameters to the technique

Processing of laser scanning data in Geomagic software on example of Mislej portal

The main topic of this graduation thesis is the processing of data, acquired with the terrestrial laser scanning technology, aimed at constructing a geometrically and topologically consistent 3D model. Terrestrial laser scanning and the complete modeling procedure from a point cloud to the final photo- realistic 3D model is described in the thesis. Some examples of mathematic algorithms applied during data processing are presented. Operation of the software processing package Geomagic is explained in detail, as well as the software’s individual functions and its advantages in comparison with other competing software packages. Within this thesis, a practical project of 3D data processing in Geomagic software has been carried out on the example of the Mislej portal. This portal with the belonging building is recorded in the Register of Cultural Heritage

Vision numérique et modèles 3D pour imagerie moléculaire sur petits animaux par tomographie optique

Typiquement, en tomographie optique diffuse (TOD), les mesures optiques sont prises en amenant des fibres optiques en contact avec le sujet ou en faisant baigner le sujet dans un fluide adaptateur d'indice. Ces deux approches simplifient grandement le problème inverse pour la reconstruction tomographique, car seule la propagation de la lumière dans les tissus biologiques doit être considérée. Dans le cas de l'imagerie sur petits animaux, il est très difficile d'amener des fibres optiques en contact avec le sujet de façon automatisée sans l'écraser et sans changer sa géométrie. L'utilisation de fluides adaptateurs d'indice simplifie la géométrie du problème à celle du contenant, généralement de forme cylindrique, où se trouve l'animal. Par contre, il n'est pas pratique d'avoir à entretenir un tel système et il est difficile de mettre l'animal dans un fluide sans le noyer. L'utilisation de fluides adaptateurs d'indice atténue le signal optique menant à des mesures plus bruitées. Les sytèmes sans contact permettent d'éviter tous les problèmes mentionnés précédemment, mais nécessitent la mesure de la forme extérieure du sujet. Dans le cadre des présents travaux de recherche, un système de vision numérique utilisant une paire de caméras et un laser pour mesurer la forme extérieure 3D de sujets est présenté. La conception du système de vision numérique 3D vise à faciliter son intégration au système de TOD qui est présentement développé au sein du groupe TomOptUS. Le principal avantage du système de vision numérique est de minimiser la complexité du système de TOD en utlisant le même laser pour les mesures tomographiques optiques et pour les mesures 3D, permettant simultanément l'acquisition de modèles 3D et de données optiques. Cette approche permet de mesurer la position exacte à laquelle la lumière du laser est injectée dans le sujet, alors que cette postion est habituellement déduite et non mesurée par les autres systèmes. Cette information est extrêmement importante pour la reconstruction tomographique. Des mesures 3D précises (<1mm) sont obtenues à l'aide d'algorithmes pour l'étalonnage de l'axe de rotation et de translation. Des mesures 3D d'une forme de référence et d'une souris sont présentées démontrant la précision et l'efficacité du système

Point Cloud Technology for Analysis of Existing Structures

For this thesis, a study was completed on two different structures on the UCF Orlando campus through the use of both structural plans and point cloud technology. The results sought to understand the viability of point cloud technology as an accurate tool for the static and dynamic modal analysis of existing structures. For static analysis, a portion of the framing of Spectrum Stadium was rendered, modeled, analyzed and compared to a previous case study. The results emphasized how different users can render dissimilar member sizes and lengths due to human judgment on point cloud visuals. The study also found that structural plans cannot always be relied upon as the most accurate source for analysis as the new point cloud produced more accurate results than the structural plans when compared to the control model. For the pedestrian bridge, the structure was scanned, rendered and modeled for both static and dynamic modal analysis. The point cloud produced from scanning the bridge was modified twice in order to have three distinct point clouds with varying densities: fine, medium and coarse. These three cases were compared to structural plans in a static analysis. The fine point cloud produced the most accurate displacement results with an accuracy above 96%. The data sources were also compared to experimental data under dynamic modal analysis to discover how lessening the density of point clouds affect the accuracy of results. The analysis showed that point cloud technology can give you an accuracy of 88% and above for frequency while also producing MAC values exceeding 0.9 consistently. Also, changes in density were found to change the accuracy of results but the numeric values stayed within close proximity by not differing more than 10%. This thesis shines a light on the accuracy point cloud technology can ascertain and the potential it has within engineering

Diseño de un esquema de muestreo de datos para la carga y almacenamiento progresivo de nubes de puntos

En este documento se presenta una técnica para simplificar nubes de puntos, la cual se basa en la información espacial contenida en una nube de puntos no estructurada. Para lograr esto, se pretende reorganizar el conjunto de datos de manera tal que al inicio del archivo se ubiquen los puntos más significativos para el modelo 3D, esto permite que el conjunto de datos pueda ser cargado, visualizado o almacenado de forma progresiva. Para clasificar los puntos de acuerdo a su importancia dentro del conjunto de datos, el modelo 3D es dividido en segmentos relativamente planos usando un algoritmo de crecimiento de regiones, luego cada región es analizada para clasificar los datos dentro de ella como puntos pertenecientes a algún borde o puntos pertenecientes a zonas intermedias de la superficie. Finalmente se realiza un muestreo de los datos clasificados y se ordenan en el archivo. De esta forma el usuario puede tener el control de la cantidad de puntos que desea cargar del archivo y así se obtiene un modelo de diferentes resolucionesAbstract : In this document a technique to simplify point clouds is presented, which is based in the spatial information contained in a unstructured point cloud. To achieve this, the intention is to reorganize the data set in such a way that the most significant dots for the 3D model are located at the beginning of the file, which allows that the data set can be uploaded, viewed or stored in a progressive way. To classify the dots according to their importance within the data set, and in this way re arrange the file, the 3D model is split into segments relativity plane using a region growing algorithm, next each region is analyzed to classify the data inside it as dots belonging to any border or dots belonging to intermediate zones of the surface. Finally, a sampling of the classified data is made and they are arranged in the file. In this way the user can control the amount of dots that he wants to upload from the file and so he gets a model of different resolutionsMaestrí