Miniaturized embedded stereo vision system (MESVS)

Stereo vision is one of the fundamental problems of computer vision. It is also one of the oldest and heavily investigated areas of 3D vision. Recent advances of stereo matching methodologies and availability of high performance and efficient algorithms along with availability of fast and affordable hardware technology, have allowed researchers to develop several stereo vision systems capable of operating at real-time. Although a multitude of such systems exist in the literature, the majority of them concentrates only on raw performance and quality rather than factors such as dimension, and power requirement, which are of significant importance in the embedded settings. In this thesis a new miniaturized embedded stereo vision system (MESVS) is presented, which is miniaturized to fit within a package of 5x5cm, is power efficient, and cost-effective. Furthermore, through application of embedded programming techniques and careful optimization, MESVS achieves the real-time performance of 20 frames per second. This work discusses the various challenges involved regarding design and implementation of this system and the measures taken to tackle them

Design and implementation of a real-time miniaturized embedded stereo-vision system

The main motivation of the thesis is to develop a fully integrated, modular, small baseline (\u3c=3cm), low cost (\u3c=CAD$600), real-time miniaturized embedded stereo-vision system which fits within 5x5cm and consumes very low power ([email protected]). The system consists of two small profile cameras and a dualcore embedded media processor, running at 600MHz per core. The stereo-matching engine performs sub-sampling, rectification, pre-processing using census transform, correlation-based Sum of Hamming Distance matching using three levels of recursion, LRC check and post-processing. The novel post processing algorithm removes outliers due to low-texture regions and depth-discontinuities. A quantitative performance of the post processing algorithm is presented which shows that for all regions, it has an average percentage improvement of 13.61% (based on 2006 Middlebury dataset). To further enhance the performance of the system, optimization steps are employed to achieve a speed of around 10fps for disparity maps in MESVS-I and 20fps in MESVS-II system

Parametric Dense Stereovision Implementation on a System-on Chip (SoC)

This paper proposes a novel hardware implementation of a dense recovery of stereovision 3D measurements. Traditionally 3D stereo systems have imposed the maximum number of stereo correspondences, introducing a large restriction on artificial vision algorithms. The proposed system-on-chip (SoC) provides great performance and efficiency, with a scalable architecture available for many different situations, addressing real time processing of stereo image flow. Using double buffering techniques properly combined with pipelined processing, the use of reconfigurable hardware achieves a parametrisable SoC which gives the designer the opportunity to decide its right dimension and features. The proposed architecture does not need any external memory because the processing is done as image flow arrives. Our SoC provides 3D data directly without the storage of whole stereo images. Our goal is to obtain high processing speed while maintaining the accuracy of 3D data using minimum resources. Configurable parameters may be controlled by later/parallel stages of the vision algorithm executed on an embedded processor. Considering hardware FPGA clock of 100 MHz, image flows up to 50 frames per second (fps) of dense stereo maps of more than 30,000 depth points could be obtained considering 2 Mpix images, with a minimum initial latency. The implementation of computer vision algorithms on reconfigurable hardware, explicitly low level processing, opens up the prospect of its use in autonomous systems, and they can act as a coprocessor to reconstruct 3D images with high density information in real time

Stereoscopic hand-detection system based on FPGA

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Major de Telecomunicações). Faculdade de Engenharia. Universidade do Porto. 200

Implementação de rectificação de imagens estéreo num sistema embutido baseado em FPGA

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 200

A Miniature Stereo Vision Machine (MSVM-III) for Dense Disparity Mapping,”

Abstract We have developed a miniature stereovision machine (MSVM-III

Contributions pour les applications de réalité augmentée. Suivi visuel et recalage 2D. Suivi d'objets 3D représentés par des modèles par points

Cette thèse présente plusieurs méthodes de recalage pour les applications de réalité augmentée (R.A.). Nous décrivons d'abord des expériences de R.A. utilisant des recalages et suivis uniquement 2D. Nous nous intéressons ensuite au suivi visuel d'un objet naturel dont on connaît un modèle 3D et dont l'image peut ainsi être augmentée avec une cohérence spatiale et temporelle. Dans une première partie, nous proposons d'abord d'utiliser un recalage homographique en temps-réel pour augmenter des séquences filmées par une caméra en rotation autour de son centre optique. Dans une autre application, des transformations non rigides sont calculées hors ligne pour augmenter les images naturelles des parois gravées d'une grotte préhistorique. Le recalage géométrique des interprétations graphiques d'un préhistorien permet de créer un logiciel de découverte interactive des parois. Dans la seconde et majeure partie de ce travail, nous partons des méthodes de suivi 3D de l'état de l'art prises parmi les plus performantes. Ces méthodes consistent à suivre un objet naturel connaissant sa représentation par un maillage 3D. Nous proposons une approche de suivi visuel 3D utilisant quant à elle des modèles par points de l'objet. Ce type de modèle, caractérisé par l'absence de topologie, est encore peu utilisé en vision par ordinateur mais il présente une souplesse intéressante par rapport aux modèles constitués de facettes. La méthode de suivi que nous proposons consiste à interpréter des mises en correspondances 2D entre points d'intérêt en termes de variations de positions 3D. Le processus d'estimation sous-jacent utilise des champs de mouvements déduits des modèles 3D par points et des reconstructions par Moving Least Squares et splatting. Ces techniques développées par la communauté d'informatique graphique s'attachent à reconstruire localement (explicitement ou implicitement) la surface de l'objet à suivre et certains attributs dénis de manière éparse sur le nuage de points. Nous les adaptons à l'interpolation des champs de mouvements. L'avantage de notre approche est d'aboutir à un algorithme enchaînant quelques étapes d'estimation linéaires pour la détermination du mouvement 3D inter-images. Notre technique de résolution est intégrée à une adaptation originale d'un algorithme de suivi visuel de l'état de l'art qui repose sur un suivi hybride, combinant les informations issues de l'image précédente et celles apportées par des images clés acquises hors ligne. Une des particularités de notre implantation vient aussi de l'exploitation des capacités des unités de calcul graphiques (GPU) modernes pour les parties critiques de l'algorithme (extraction de points d'intérêt, appariement et calcul de champs de mouvements)

Single chip solution for stabilization control & monocular visual servoing of small-scale quadrotor helicopter

This thesis documents the research undertaken to develop a high-performing design of a small-scale quadrotor (four-rotor) helicopter capable of delivering the speed and robustness required for agile motion while also featuring an autonomous visual servoing capability within the size, weight, and power (SWaP) constraint package. The state of the art research was reviewed, and the areas in the existing design methodologies that can potentially be improved were identified, which included development of a comprehensive dynamics model of quadrotor, design and construction of a performance optimized prototype vehicle, high-performance actuator design, design of a robust attitude stabilization controller, and a single chip solution for autonomous vision based position control. The gaps in the current art of designing each component were addressed individually. The outcomes of the corresponding development activities include a high-fidelity dynamics and control model of the vehicle. The model was developed using multi-body bond graph modeling approach to incorporate the dynamic interactions between the frame body and propulsion system. Using an algorithmic size, payload capacity, and flight endurance optimization approach, a quadrotor prototype was designed and constructed. In order to conform to the optimized geometric and performance parameters, the frame of the prototype was constructed using printed circuit board (PCB) technology and processing power was integrated using a single chip field programmable gate array (FPGA) technology. Furthermore, to actuate the quadrotor at a high update rate while also improving the power efficiency of the actuation system, a ground up FPGA based brushless direct current (BLDC) motor driver was designed using a low-loss commutation scheme and hall effect sensors. A proportional-integral-derivative (PID) technology based closed loop motor speed controller was also implemented in the same FPGA hardware for precise speed control of the motors. In addition, a novel control law was formulated for robust attitude stabilization by adopting a cascaded architecture of active disturbance rejection control (ADRC) technology and PID control technology. Using the same single FPGA chip to drive an on-board downward looking camera, a monocular visual servoing solution was developed to integrate an autonomous position control feature with the quadrotor. Accordingly, a numerically simple relative position estimation technique was implemented in FPGA hardware that relies on a passive landmark/target for 3-D position estimation. The functionality and effectiveness of the synthesized design were evaluated by performance benchmarking experiments conducted on each individual component as well as on the complete system constructed from these components. It was observed that the proposed small-scale quadrotor, even though just 43 cm in diameter, can lift 434 gm of payload while operating for 18 min. Among the ground up designed components, the FPGA based motor driver demonstrated a maximum of 4% improvement in the power consumption and at the same time can handle a command update at a rate of 16 kHz. The cascaded attitude stabilization controller can asymptotically stabilize the vehicle within 426 ms of the command update. Robust control performance under stochastic wind gusts is also observed from the stabilization controller. Finally, the single chip FPGA based monocular visual servoing solution can estimate pose information at the camera rate of 37 fps and accordingly the quadrotor can autonomously climb/descend and/or hover over a passive target

Pilot study for subgroup classification for autism spectrum disorder based on dysmorphology and physical measurements in Chinese children

Poster Sessions: 157 - Comorbid Medical Conditions: abstract 157.058 58BACKGROUND: Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder affecting individuals along a continuum of severity in communication, social interaction and behaviour. The impact of ASD significantly varies amongst individuals, and the cause of ASD can originate broadly between genetic and environmental factors. Objectives: Previous ASD researches indicate that early identification combined with a targeted treatment plan involving behavioural interventions and multidisciplinary therapies can provide substantial improvement for ASD patients. Currently there is no cure for ASD, and the clinical variability and uncertainty of the disorder still remains. Hence, the search to unravel heterogeneity within ASD by subgroup classification may provide clinicians with a better understanding of ASD and to work towards a more definitive course of action. METHODS: In this study, a norm of physical measurements including height, weight, head circumference, ear length, outer and inner canthi, interpupillary distance, philtrum, hand and foot length was collected from 658 Typical Developing (TD) Chinese children aged 1 to 7 years (mean age of 4.19 years). The norm collected was compared against 80 ASD Chinese children aged 1 to 12 years (mean age of 4.36 years). We then further attempted to find subgroups within ASD based on identifying physical abnormalities; individuals were classified as (non) dysmorphic with the Autism Dysmorphology Measure (ADM) from physical examinations of 12 body regions. RESULTS: Our results show that there were significant differences between ASD and TD children for measurements in: head circumference (p=0.009), outer (p=0.021) and inner (p=0.021) canthus, philtrum length (p=0.003), right (p=0.023) and left (p=0.20) foot length. Within the 80 ASD patients, 37(46%) were classified as dysmorphic (p=0.00). CONCLUSIONS: This study attempts to identify subgroups within ASD based on physical measurements and dysmorphology examinations. The information from this study seeks to benefit ASD community by identifying possible subtypes of ASD in Chinese population; in seek for a more definitive diagnosis, referral and treatment plan.published_or_final_versio