3D mapping and path planning from range data

This thesis reports research on mapping, terrain classification and path planning. These are classical problems in robotics, typically studied independently, and here we link such problems by framing them within a common proprioceptive modality, that of three-dimensional laser range scanning. The ultimate goal is to deliver navigation paths for challenging mobile robotics scenarios. For this reason we also deliver safe traversable regions from a previously computed globally consistent map. We first examine the problem of registering dense point clouds acquired at different instances in time. We contribute with a novel range registration mechanism for pairs of 3D range scans using point-to-point and point-to-line correspondences in a hierarchical correspondence search strategy. For the minimization we adopt a metric that takes into account not only the distance between corresponding points, but also the orientation of their relative reference frames. We also propose FaMSA, a fast technique for multi-scan point cloud alignment that takes advantage of the asserted point correspondences during sequential scan matching, using the point match history to speed up the computation of new scan matches. To properly propagate the model of the sensor noise and the scan matching, we employ first order error propagation, and to correct the error accumulation from local data alignment, we consider the probabilistic alignment of 3D point clouds using a delayed-state Extended Information Filter (EIF). In this thesis we adapt the Pose SLAM algorithm to the case of 3D range mapping, Pose SLAM is the variant of SLAM where only the robot trajectory is estimated and where sensor data is solely used to produce relative constraints between robot poses. These dense mapping techniques are tested in several scenarios acquired with our 3D sensors, producing impressively rich 3D environment models. The computed maps are then processed to identify traversable regions and to plan navigation sequences. In this thesis we present a pair of methods to attain high-level off-line classification of traversable areas, in which training data is acquired automatically from navigation sequences. Traversable features came from the robot footprint samples during manual robot motion, allowing us to capture terrain constrains not easy to model. Using only some of the traversed areas as positive training samples, our algorithms are tested in real scenarios to find the rest of the traversable terrain, and are compared with a naive parametric and some variants of the Support Vector Machine. Later, we contribute with a path planner that guarantees reachability at a desired robot pose with significantly lower computation time than competing alternatives. To search for the best path, our planner incrementally builds a tree using the A* algorithm, it includes a hybrid cost policy to efficiently expand the search tree, combining random sampling from the continuous space of kinematically feasible motion commands with a cost to goal metric that also takes into account the vehicle nonholonomic constraints. The planer also allows for node rewiring, and to speed up node search, our method includes heuristics that penalize node expansion near obstacles, and that limit the number of explored nodes. The method book-keeps visited cells in the configuration space, and disallows node expansion at those configurations in the first full iteration of the algorithm. We validate the proposed methods with experiments in extensive real scenarios from different very complex 3D outdoors environments, and compare it with other techniques such as the A*, RRT and RRT* algorithms.Esta tesis reporta investigación sobre el mapeo, clasificación de terreno y planificación de trayectorias. Estos son problemas clásicos en robótica los cuales generalmente se estudian de forma independiente, aquí se vinculan enmarcandolos con una modalidad propioceptiva común: un láser de rango 3D. El objetivo final es ofrecer trayectorias de navegación para escenarios complejos en el marco de la robótica móvil. Por esta razón también entregamos regiones transitables en un mapa global consistente calculado previamente. Primero examinamos el problema de registro de nubes de puntos adquiridas en diferentes instancias de tiempo. Contribuimos con un novedoso mecanismo de registro de pares de imagenes de rango 3D usando correspondencias punto a punto y punto a línea, en una estrategia de búsqueda de correspondencias jerárquica. Para la minimización optamos por una metrica que considera no sólo la distancia entre puntos, sino también la orientación de los marcos de referencia relativos. También proponemos FAMSA, una técnica para el registro rápido simultaneo de multiples nubes de puntos, la cual aprovecha las correspondencias de puntos obtenidas durante el registro secuencial, usando inicialmente la historia de correspondencias para acelerar el cálculo de las correspondecias en los nuevos registros de imagenes. Para propagar adecuadamente el modelo del ruido del sensor y del registro de imagenes, empleamos la propagación de error de primer orden, y para corregir el error acumulado del registro local, consideramos la alineación probabilística de nubes de puntos 3D utilizando un Filtro Extendido de Información de estados retrasados. En esta tesis adaptamos el algóritmo Pose SLAM para el caso de mapas con imagenes de rango 3D, Pose SLAM es la variante de SLAM donde solamente se estima la trayectoria del robot, usando los datos del sensor como restricciones relativas entre las poses robot. Estas técnicas de mapeo se prueban en varios escenarios adquiridos con nuestros sensores 3D produciendo modelos 3D impresionantes. Los mapas obtenidos se procesan para identificar regiones navegables y para planificar secuencias de navegación. Presentamos un par de métodos para lograr la clasificación de zonas transitables fuera de línea. Los datos de entrenamiento se adquieren de forma automática usando secuencias de navegación obtenidas manualmente. Las características transitables se captan de las huella de la trayectoria del robot, lo cual permite capturar restricciones del terreno difíciles de modelar. Con sólo algunas de las zonas transitables como muestras de entrenamiento positivo, nuestros algoritmos se prueban en escenarios reales para encontrar el resto del terreno transitable. Los algoritmos se comparan con algunas variantes de la máquina de soporte de vectores (SVM) y una parametrizacion ingenua. También, contribuimos con un planificador de trayectorias que garantiza llegar a una posicion deseada del robot en significante menor tiempo de cálculo a otras alternativas. Para buscar el mejor camino, nuestro planificador emplea un arbol de busqueda incremental basado en el algoritmo A*. Incluimos una póliza de coste híbrido para crecer de manera eficiente el árbol, combinando el muestro aleatorio del espacio continuo de comandos cinemáticos del robot con una métrica de coste al objetivo que también concidera las cinemática del robot. El planificador además permite reconectado de nodos, y, para acelerar la búsqueda de nodos, se incluye una heurística que penaliza la expansión de nodos cerca de los obstáculos, que limita el número de nodos explorados. El método conoce las céldas que ha visitado del espacio de configuraciones, evitando la expansión de nodos en configuraciones que han sido vistadas en la primera iteración completa del algoritmo. Los métodos propuestos se validán con amplios experimentos con escenarios reales en diferentes entornos exteriores, asi como su comparación con otras técnicas como los algoritmos A*, RRT y RRT*.Postprint (published version

Stereo-Based Environment Scanning for Immersive Telepresence

The processing power and network bandwidth required for true immersive telepresence applications are only now beginning to be available. We draw from our experience developing stereo based tele-immersion prototypes to present the main issues arising when building these systems. Tele-immersion is a new medium that enables a user to share a virtual space with remote participants. The user is immersed in a rendered three-dimensional (3-D) world that is transmitted from a remote site. To acquire this 3-D description, we apply binocular and trinocular stereo techniques which provide a view-independent scene description. Slow processing cycles or long network latencies interfere with the users\u27 ability to communicate, so the dense stereo range data must be computed and transmitted at high frame rates. Moreover, reconstructed 3-D views of the remote scene must be as accurate as possible to achieve a sense of presence. We address both issues of speed and accuracy using a variety of techniques including the power of supercomputing clusters and a method for combining motion and stereo in order to increase speed and robustness. We present the latest prototype acquiring a room-size environment in real time using a supercomputing cluster, and we discuss its strengths and current weaknesses

Tool for spatial and dynamic representation of artistic performances

This proposal aims to explore the use of available technologies for video representation of sets and performers in order to serve as support for composition processes and artistic performer rehearsals, while focusing in representing the performer’s body and its movements, and its relation with objects belonging to the three-dimensional space of their performances. This project’s main goal is to design and develop a system that can spatially represent the performer and its movements, by means of capturing processes and reconstruction using a camera device, as well as enhance the three-dimensional space where the performance occurs by allowing interaction with virtual objects and by adding a video component, either for documentary purposes, or for live performances effects (for example, using video mapping video techniques in captured video or projection during a performance)

Website Architecture, Information Flows and Cognitive Models

This paper explores the relation between new digital genres configuration and their users’ previous knowledge patterns from an interlinguistic perspective. More precisely, first we analyse two models that underlie the formal architecture of websites. For that purpose we introduce diverse pieces of software that allow for visualization of website organization in terms of nodes and links. Then, we show the most entrenched metaphoric models that provide cognitive tools for users to understand website configuration and usage, in an English speaking culture. Finally, we discuss to what extent these models can be transferred and learned by users from other cultures, particularly in Spanish speaking communitie

Human Factors Considerations in System Design

Human factors considerations in systems design was examined. Human factors in automated command and control, in the efficiency of the human computer interface and system effectiveness are outlined. The following topics are discussed: human factors aspects of control room design; design of interactive systems; human computer dialogue, interaction tasks and techniques; guidelines on ergonomic aspects of control rooms and highly automated environments; system engineering for control by humans; conceptual models of information processing; information display and interaction in real time environments

3D data fusion from multiple sensors and its applications

The introduction of depth cameras in the mass market contributed to make computer vision applicable to many real world applications, such as human interaction in virtual environments, autonomous driving, robotics and 3D reconstruction. All these problems were originally tackled by means of standard cameras, but the intrinsic ambiguity in the bidimensional images led to the development of depth cameras technologies. Stereo vision was first introduced to provide an estimate of the 3D geometry of the scene. Structured light depth cameras were developed to use the same concepts of stereo vision but overcome some of the problems of passive technologies. Finally, Time-of-Flight (ToF) depth cameras solve the same depth estimation problem by using a different technology. This thesis focuses on the acquisition of depth data from multiple sensors and presents techniques to efficiently combine the information of different acquisition systems. The three main technologies developed to provide depth estimation are first reviewed, presenting operating principles and practical issues of each family of sensors. The use of multiple sensors then is investigated, providing practical solutions to the problem of 3D reconstruction and gesture recognition. Data from stereo vision systems and ToF depth cameras are combined together to provide a higher quality depth map. A confidence measure of depth data from the two systems is used to guide the depth data fusion. The lack of datasets with data from multiple sensors is addressed by proposing a system for the collection of data and ground truth depth, and a tool to generate synthetic data from standard cameras and ToF depth cameras. For gesture recognition, a depth camera is paired with a Leap Motion device to boost the performance of the recognition task. A set of features from the two devices is used in a classification framework based on Support Vector Machines and Random Forests

Reconstruction active par projection de lumière non structurée

Cette thèse porte sur la reconstruction active de modèles 3D à l’aide d’une caméra et d’un projecteur. Les méthodes de reconstruction standards utilisent des motifs de lumière codée qui ont leurs forces et leurs faiblesses. Nous introduisons de nouveaux motifs basés sur la lumière non structurée afin de pallier aux manques des méthodes existantes. Les travaux présentés s’articulent autour de trois axes : la robustesse, la précision et finalement la comparaison des patrons de lumière non structurée aux autres méthodes. Les patrons de lumière non structurée se différencient en premier lieu par leur robustesse aux interréflexions et aux discontinuités de profondeur. Ils sont conçus de sorte à homogénéiser la quantité d’illumination indirecte causée par la projection sur des surfaces difficiles. En contrepartie, la mise en correspondance des images projetées et capturées est plus complexe qu’avec les méthodes dites structurées. Une méthode d’appariement probabiliste et efficace est proposée afin de résoudre ce problème. Un autre aspect important des reconstructions basées sur la lumière non structurée est la capacité de retrouver des correspondances sous-pixels, c’est-à-dire à un niveau de précision plus fin que le pixel. Nous présentons une méthode de génération de code de très grande longueur à partir des motifs de lumière non structurée. Ces codes ont l’avantage double de permettre l’extraction de correspondances plus précises tout en requérant l’utilisation de moins d’images. Cette contribution place notre méthode parmi les meilleures au niveau de la précision tout en garantissant une très bonne robustesse. Finalement, la dernière partie de cette thèse s’intéresse à la comparaison des méthodes existantes, en particulier sur la relation entre la quantité d’images projetées et la qualité de la reconstruction. Bien que certaines méthodes nécessitent un nombre constant d’images, d’autres, comme la nôtre, peuvent se contenter d’en utiliser moins aux dépens d’une qualité moindre. Nous proposons une méthode simple pour établir une correspondance optimale pouvant servir de référence à des fins de comparaison. Enfin, nous présentons des méthodes hybrides qui donnent de très bons résultats avec peu d’images.This thesis deals with active 3D reconstruction from camera-projector systems. Standard reconstruction methods use coded light patterns that come with their strengths and weaknesses. We introduce unstructured light patterns that feature several improvements compared to the current state of the art. The research presented revolves around three main axes : robustness, precision and comparison of existing unstructured light patterns to existing methods. Unstructured light patterns stand out first and foremost by their robustness to interreflections and depth discontinuities. They are specifically designed to homogenize the indirect lighting generated by their projection on hard to scan surfaces. The downside of these patterns is that matching projected and captured images is not straightforward anymore. A probabilistic correspondence method is formulated to solve this problem efficiently. Another important aspect of reconstruction obtained with unstructured light pat- terns is their ability to recover subpixel correspondences, that is with a precision finer than the pixel level. We present a method to produce long codes using unstructured light. These codes enable us to extract more precise correspondences while requiring less patterns. This contribution makes our method one of the most accurate - yet robust to standard challenges - method of active reconstruction in the domain. Finally, the last part of this thesis adresses the comparison of existing reconstruction methods on several aspects, but mainly on the impact of using less and less patterns on the quality of the reconstruction. While some methods need a fixed number of images, some, like ours, can accommodate fewer patterns in exchange for some quality loss. We devise a simple method to capture an optimal correspondence map that can be used as a groundtruth for comparison purposes. Last, we present several hybrid methods that perform quite well even with few images

Study of the interaction with a virtual 3D environment displayed on a smartphone

Les environnements virtuels à 3D (EV 3D) sont de plus en plus utilisés dans différentes applications telles que la CAO, les jeux ou la téléopération. L'évolution des performances matérielles des Smartphones a conduit à l'introduction des applications 3D sur les appareils mobiles. En outre, les Smartphones offrent de nouvelles capacités bien au-delà de la communication vocale traditionnelle qui sont consentis par l'intégrité d'une grande variété de capteurs et par la connectivité via Internet. En conséquence, plusieurs intéressantes applications 3D peuvent être conçues en permettant aux capacités de l'appareil d'interagir dans un EV 3D. Sachant que les Smartphones ont de petits et aplatis écrans et que EV 3D est large, dense et contenant un grand nombre de cibles de tailles différentes, les appareils mobiles présentent certaines contraintes d'interaction dans l'EV 3D comme : la densité de l'environnement, la profondeur de cibles et l'occlusion. La tâche de sélection fait face à ces trois problèmes pour sélectionner une cible. De plus, la tâche de sélection peut être décomposée en trois sous-tâches : la Navigation, le Pointage et la Validation. En conséquence, les chercheurs dans un environnement virtuel 3D ont développé de nouvelles techniques et métaphores pour l'interaction en 3D afin d'améliorer l'utilisation des applications 3D sur les appareils mobiles, de maintenir la tâche de sélection et de faire face aux problèmes ou facteurs affectant la performance de sélection. En tenant compte de ces considérations, cette thèse expose un état de l'art des techniques de sélection existantes dans un EV 3D et des techniques de sélection sur Smartphone. Il expose les techniques de sélection dans un EV 3D structurées autour des trois sous-tâches de sélection: navigation, pointage et validation. En outre, il décrit les techniques de désambiguïsation permettant de sélectionner une cible parmi un ensemble d'objets présélectionnés. Ultérieurement, il expose certaines techniques d'interaction décrites dans la littérature et conçues pour être implémenter sur un Smartphone. Ces techniques sont divisées en deux groupes : techniques effectuant des tâches de sélection bidimensionnelle sur un Smartphone et techniques exécutant des tâches de sélection tridimensionnelle sur un Smartphone. Enfin, nous exposons les techniques qui utilisaient le Smartphone comme un périphérique de saisie. Ensuite, nous discuterons la problématique de sélection dans un EV 3D affichée sur un Smartphone. Il expose les trois problèmes identifiés de sélection : la densité de l'environnement, la profondeur des cibles et l'occlusion. Ensuite, il établit l'amélioration offerte par chaque technique existante pour la résolution des problèmes de sélection. Il analyse les atouts proposés par les différentes techniques, la manière dont ils éliminent les problèmes, leurs avantages et leurs inconvénients. En outre, il illustre la classification des techniques de sélection pour un EV 3D en fonction des trois problèmes discutés (densité, profondeur et occlusion) affectant les performances de sélection dans un environnement dense à 3D. Hormis pour les jeux vidéo, l'utilisation d'environnement virtuel 3D sur Smartphone n'est pas encore démocratisée. Ceci est dû au manque de techniques d'interaction proposées pour interagir avec un dense EV 3D composé de nombreux objets proches les uns des autres et affichés sur un petit écran aplati et les problèmes de sélection pour afficher l' EV 3D sur un petit écran plutôt sur un grand écran. En conséquence, cette thèse se concentre sur la proposition et la description du fruit de cette étude : la technique d'interaction DichotoZoom. Elle compare et évalue la technique proposée à la technique de circulation suggérée par la littérature. L'analyse comparative montre l'efficacité de la technique DichotoZoom par rapport à sa contrepartie. Ensuite, DichotoZoom a été évalué selon les différentes modalités d'interaction disponibles sur les Smartphones. Cette évaluation montre la performance de la technique de sélection proposée basée sur les quatre modalités d'interaction suivantes : utilisation de boutons physiques ou sous forme de composants graphiques, utilisation d'interactions gestuelles via l'écran tactile ou le déplacement de l'appareil lui-même. Enfin, cette thèse énumère nos contributions dans le domaine des techniques d'interaction 3D utilisées dans un environnement virtuel 3D dense affiché sur de petits écrans et propose des travaux futurs.3D Virtual Environments (3D VE) are more and more used in different applications such as CAD, games, or teleoperation. Due to the improvement of smartphones hardware performance, 3D applications were also introduced to mobile devices. In addition, smartphones provide new computing capabilities far beyond the traditional voice communication. They are permitted by the variety of built-in sensors and the internet connectivity. In consequence, interesting 3D applications can be designed by enabling the device capabilities to interact in a 3D VE. Due to the fact that smartphones have small and flat screens and that a 3D VE is wide and dense with a large number of targets of various sizes, mobile devices present some constraints in interacting on the 3D VE like: the environment density, the depth of targets and the occlusion. The selection task faces these three problems to select a target. In addition, the selection task can be decomposed into three subtasks: Navigation, Pointing and Validation. In consequence, researchers in 3D virtual environment have developed new techniques and metaphors for 3D interaction to improve 3D application usability on mobile devices, to support the selection task and to face the problems or factors affecting selection performance. In light of these considerations, this thesis exposes a state of the art of the existing selection techniques in 3D VE and the selection techniques on smartphones. It exposes the selection techniques in 3D VE structured around the selection subtasks: navigation, pointing and validation. Moreover, it describes disambiguation techniques providing the selection of a target from a set of pre-selected objects. Afterward, it exposes some interaction techniques described in literature and designed for implementation on Smartphone. These techniques are divided into two groups: techniques performing two-dimensional selection tasks on smartphones, and techniques performing three-dimensional selection tasks on smartphones. Finally, we expose techniques that used the smartphone as an input device. Then, we will discuss the problematic of selecting in 3D VE displayed on a Smartphone. It exposes the three identified selection problems: the environment density, the depth of targets and the occlusion. Afterward, it establishes the enhancement offered by each existing technique in solving the selection problems. It analysis the assets proposed by different techniques, the way they eliminates the problems, their advantages and their inconvenient. Furthermore, it illustrates the classification of the selection techniques for 3D VE according to the three discussed problems (density, depth and occlusion) affecting the selection performance in a dense 3D VE. Except for video games, the use of 3D virtual environment (3D VE) on Smartphone has not yet been popularized. This is due to the lack of interaction techniques to interact with a dense 3D VE composed of many objects close to each other and displayed on a small and flat screen and the selection problems to display the 3D VE on a small screen rather on a large screen. Accordingly, this thesis focuses on defining and describing the fruit of this study: DichotoZoom interaction technique. It compares and evaluates the proposed technique to the Circulation technique, suggested by the literature. The comparative analysis shows the effectiveness of DichotoZoom technique compared to its counterpart. Then, DichotoZoom was evaluated in different modalities of interaction available on Smartphones. It reports on the performance of the proposed selection technique based on the following four interaction modalities: using physical buttons, using graphical buttons, using gestural interactions via touchscreen or moving the device itself. Finally, this thesis lists our contributions to the field of 3D interaction techniques used in a dense 3D virtual environment displayed on small screens and proposes some future works