Learning Paradigms Exemplified by Virtual Experiments with Honey Bees

Learning is based on rules that can be elucidated by behavioural experiments. This article focuses on virtual experiments, in which non-associative learning (habituation, sensitization) and principles of associative learning (contiguity, inhibitory learning, generalization, overshadowing, positive and negative patterning) can be examined using 'virtual' honey bees in PER (Proboscis Reaction Extension) conditioning experiments. Users can develop experimental designs, simulate and document the experiments and find explanations and suggestions for the analysis of the learning experiments. The virtual experiments are based on video sequences and data from actual learning experiments. The bees' responses are determined by probability-based learning profiles.

Registration of Sub-Sequence and Multi-Camera Reconstructions for Camera Motion Estimation

This paper presents different application scenarios for which the registration of sub-sequence reconstructions or multi-camera reconstructions is essential for successful camera motion estimation and 3D reconstruction from video. The registration is achieved by merging unconnected feature point tracks between the reconstructions. One application is drift removal for sequential camera motion estimation of long sequences. The state-of-the-art in drift removal is to apply a RANSAC approach to find unconnected feature point tracks. In this paper an alternative spectral algorithm for pairwise matching of unconnected feature point tracks is used. It is then shown that the algorithms can be combined and applied to novel scenarios where independent camera motion estimations must be registered into a common global coordinate system. In the first scenario multiple moving cameras, which capture the same scene simultaneously, are registered. A second new scenario occurs in situations where the tracking of feature points during sequential camera motion estimation fails completely, e.g., due to large occluding objects in the foreground, and the unconnected tracks of the independent reconstructions must be merged. In the third scenario image sequences of the same scene, which are captured under different illuminations, are registered. Several experiments with challenging real video sequences demonstrate that the presented techniques work in practice.

Reflectance Transfer for Material Editing and Relighting

We present a new approach to diffuse reflectance estimation for dynamic scenes. Non-parametric image statistics are used to transfer reflectance properties from a static example set to a dynamic image sequence. The approach allows diffuse reflectance estimation for surface materials with inhomogeneous appearance, such as those which commonly occur with patterned or textured clothing. Material editing is also possible by transferring edited reflectance properties. Material reflectance properties are initially estimated from static images of the subject under multiple directional illuminations using photometric stereo. The estimated reflectance together with the corresponding image under uniform ambient illumination form a prior set of reference material observations. Material reflectance properties are then estimated for video sequences of a moving person captured under uniform ambient illumination by matching the observed local image statistics to the reference observations. Results demonstrate that the transfer of reflectance properties enables estimation of the dynamic surface normals and subsequent relighting combined with material editing. This approach overcomes limitations of previous work on material transfer and relighting of dynamic scenes which was limited to surfaces with regions of homogeneous reflectance. We evaluate our approach for relighting 3D model sequences reconstructed from multiple view video. Comparison to previous model relighting demonstrates improved reproduction of detailed texture and shape dynamics.

Synchronization of two independently moving cameras without feature correspondences

In this work, a method that synchronizes two video sequences is proposed. Unlike previous methods, which require the existence of correspondences between features tracked in the two sequences, and/or that the cameras are static or jointly moving, the proposed approach does not impose any of these constraints. It works when the cameras move independently, even if different features are tracked in the two sequences. The assumptions underlying the proposed strategy are that the intrinsic parameters of the cameras are known and that two rigid objects, with independent motions on the scene, are visible in both sequences. The relative motion between these objects is used as clue for the synchronization. The extrinsic parameters of the cameras are assumed to be unknown. A new synchronization algorithm for static or jointly moving cameras that see (possibly) different parts of a common rigidly moving object is also proposed. Proof-of-concept experiments that illustrate the performance of these methods are presented, as well as a comparison with a state-of-the-art approach.

Analysis of frame-compatible subsampling structures for efficient 3DTV broadcast

The evolution of the television market is led by 3DTV technology, and this tendency can accelerate during the next years according to expert forecasts. However, 3DTV delivery by broadcast networks is not currently developed enough, and acts as a bottleneck for the complete deployment of the technology. Thus, increasing interest is dedicated to ste-reo 3DTV formats compatible with current HDTV video equipment and infrastructure, as they may greatly encourage 3D acceptance. In this paper, different subsampling schemes for HDTV compatible transmission of both progressive and interlaced stereo 3DTV are studied and compared. The frequency characteristics and preserved frequency content of each scheme are analyzed, and a simple interpolation filter is specially designed. Finally, the advantages and disadvantages of the different schemes and filters are evaluated through quality testing on several progressive and interlaced video sequences.

Kernel bandwidth estimation for moving object detection in non-stabilized cameras

The evolution of the television market is led by 3DTV technology, and this tendency can accelerate during the next years according to expert forecasts. However, 3DTV delivery by broadcast networks is not currently developed enough, and acts as a bottleneck for the complete deployment of the technology. Thus, increasing interest is dedicated to ste-reo 3DTV formats compatible with current HDTV video equipment and infrastructure, as they may greatly encourage 3D acceptance. In this paper, different subsampling schemes for HDTV compatible transmission of both progressive and interlaced stereo 3DTV are studied and compared. The frequency characteristics and preserved frequency content of each scheme are analyzed, and a simple interpolation filter is specially designed. Finally, the advantages and disadvantages of the different schemes and filters are evaluated through quality testing on several progressive and interlaced video sequences.

In-loop Feature Tracking for Structure and Motion with Out-of-core Optimization

In this paper, a novel and approach for obtaining 3D models from video sequences captured with hand-held cameras is addressed. We define a pipeline that robustly deals with different types of sequences and acquiring devices. Our system follows a divide and conquer approach: after a frame decimation that pre-conditions the input sequence, the video is split into short-length clips. This allows to parallelize the reconstruction step which translates into a reduction in the amount of computational resources required. The short length of the clips allows an intensive search for the best solution at each step of reconstruction which robustifies the system. The process of feature tracking is embedded within the reconstruction loop for each clip as opposed to other approaches. A final registration step, merges all the processed clips to the same coordinate frame

Exploration of RVC applications using an ARM multicore processor = Exploración de aplicaciones RVC empleando un procesador ARM multinúcleo

Single core capabilities have reached their maximum clock speed; new multicore architectures provide an alternative way to tackle this issue instead. The design of decoding applications running on top of these multicore platforms and their optimization to exploit all system computational power is crucial to obtain best results. Since the development at the integration level of printed circuit boards are increasingly difficult to optimize due to physical constraints and the inherent increase in power consumption, development of multiprocessor architectures is becoming the new Holy Grail. In this sense, it is crucial to develop applications that can run on the new multi-core architectures and find out distributions to maximize the potential use of the system. Today most of commercial electronic devices, available in the market, are composed of embedded systems. These devices incorporate recently multi-core processors. Task management onto multiple core/processors is not a trivial issue, and a good task/actor scheduling can yield to significant improvements in terms of efficiency gains and also processor power consumption. Scheduling of data flows between the actors that implement the applications aims to harness multi-core architectures to more types of applications, with an explicit expression of parallelism into the application. On the other hand, the recent development of the MPEG Reconfigurable Video Coding (RVC) standard allows the reconfiguration of the video decoders. RVC is a flexible standard compatible with MPEG developed codecs, making it the ideal tool to integrate into the new multimedia terminals to decode video sequences. With the new versions of the Open RVC-CAL Compiler (Orcc), a static mapping of the actors that implement the functionality of the application can be done once the application executable has been generated. This static mapping must be done for each of the different cores available on the working platform. It has been chosen an embedded system with a processor with two ARMv7 cores. This platform allows us to obtain the desired tests, get as much improvement results from the execution on a single core, and contrast both with a PC-based multiprocessor system. Las posibilidades ofrecidas por el aumento de la velocidad de la frecuencia de reloj de sistemas de un solo procesador están siendo agotadas. Las nuevas arquitecturas multiprocesador proporcionan una vía de desarrollo alternativa en este sentido. El diseño y optimización de aplicaciones de descodificación de video que se ejecuten sobre las nuevas arquitecturas permiten un mejor aprovechamiento y favorecen la obtención de mayores rendimientos. Hoy en día muchos de los dispositivos comerciales que se están lanzando al mercado están integrados por sistemas embebidos, que recientemente están basados en arquitecturas multinúcleo. El manejo de las tareas de ejecución sobre este tipo de arquitecturas no es una tarea trivial, y una buena planificación de los actores que implementan las funcionalidades puede proporcionar importantes mejoras en términos de eficiencia en el uso de la capacidad de los procesadores y, por ende, del consumo de energía. Por otro lado, el reciente desarrollo del estándar de Codificación de Video Reconfigurable (RVC), permite la reconfiguración de los descodificadores de video. RVC es un estándar flexible y compatible con anteriores codecs desarrollados por MPEG. Esto hace de RVC el estándar ideal para ser incorporado en los nuevos terminales multimedia que se están comercializando. Con el desarrollo de las nuevas versiones del compilador específico para el desarrollo de lenguaje RVC-CAL (Orcc), en el que se basa MPEG RVC, el mapeo estático, para entornos basados en multiprocesador, de los actores que integran un descodificador es posible. Se ha elegido un sistema embebido con un procesador con dos núcleos ARMv7. Esta plataforma nos permitirá llevar a cabo las pruebas de verificación y contraste de los conceptos estudiados en este trabajo, en el sentido del desarrollo de descodificadores de video basados en MPEG RVC y del estudio de la planificación y mapeo estático de los mismos.

New generation of human machine interfaces for controlling UAV through depth based gesture recognition

New forms of natural interactions between human operators and UAVs (Unmanned Aerial Vehicle) are demanded by the military industry to achieve a better balance of the UAV control and the burden of the human operator. In this work, a human machine interface (HMI) based on a novel gesture recognition system using depth imagery is proposed for the control of UAVs. Hand gesture recognition based on depth imagery is a promising approach for HMIs because it is more intuitive, natural, and non-intrusive than other alternatives using complex controllers. The proposed system is based on a Support Vector Machine (SVM) classifier that uses spatio-temporal depth descriptors as input features. The designed descriptor is based on a variation of the Local Binary Pattern (LBP) technique to efficiently work with depth video sequences. Other major consideration is the especial hand sign language used for the UAV control. A tradeoff between the use of natural hand signs and the minimization of the inter-sign interference has been established. Promising results have been achieved in a depth based database of hand gestures especially developed for the validation of the proposed system.

Subjective QoE Analysis of HTTP Adaptive Streaming Applications

Actualmente la optimization de la calidad de experiencia (Quality of Experience- QoE) de HTTP Adaptive Streaming (HAS) de video recibe una atención creciente. Este incremento de interés proviene fundamentalmente de las carencias de las soluciones actuales HAS, que, al no ser QoE-driven, no incluyen la percepción de la calidad de los usuarios finales como una parte integral de la lógica de adaptación. Por lo tanto, la obtención de información de referencia fiable en QoE en HAS presenta retos importantes, ya que las metodologías de evaluación subjetiva de la calidad de vídeo propuestas en las normas actuales no son adecuadas para tratar con la variación temporal de la calidad que es consustancial de HAS. Esta tesis investiga la influencia de la adaptación dinámica en la calidad de la transmisión de vídeo considerando métodos de evaluación subjetiva. Tras un estudio exhaustivo del estado del arte en la evaluación subjetiva de QoE en HAS, se han resaltado los retos asociados y las líneas de investigación abiertas. Como resultado, se han seleccionado dos líneas principales de investigación: el análisis del impacto en la QoE de los parámetros de las técnicas de adaptación y la investigación de las metodologías de prueba subjetiva adecuada para evaluación de QoE en HAS. Se han llevado a cabo un conjunto de experimentos de laboratorio para investigar las cuestiones planteadas mediante la utilización de diferentes metodologáas para pruebas subjetivas. El análisis estadístico muestra que no son robustas todas las suposiciones y reivindicaciones de las referencias analizadas, en particular en lo que respecta al impacto en la QoE de la frecuencia de las variaciones de calidad, de las adaptaciones suaves o abruptas y de las oscilaciones de calidad. Por otra parte, nuestros resultados confirman la influencia de otros parámetros, como la longitud de los segmentos de vídeo y la amplitud de las oscilaciones de calidad. Los resultados también muestran que tomar en consideración las características objetivas de los contenidos puede ser beneficioso para la mejora de la QoE en HAS. Además, todos los resultados han sido validados mediante extensos análisis experimentales que han incluido estudio tanto en otros laboratorios como en crowdsourcing Por último, sobre los aspectos metodológicos de las pruebas subjetivas de QoE, se ha realizado la comparación entre los resultados experimentales obtenidos a partir de un método estandarizado basado en estímulos cortos (ACR) y un método semi continuo (desarrollado para la evaluación de secuencias prolongadas de vídeo). A pesar de algunas diferencias, el resultado de los análisis estadísticos no muestra ningún efecto significativo de la metodología de prueba. Asimismo, aunque se percibe la influencia de la presencia de audio en la evaluación de degradaciones del vídeo, no se han encontrado efectos estadísticamente significativos de dicha presencia. A partir de la ausencia de influencia del método de prueba y de la presencia de audio, se ha realizado un análisis adicional sobre el impacto de realizar comparaciones estadísticas múltiples en niveles estadísticos de importancia que aumentan la probabilidad de los errores de tipo-I (falsos positivos). Nuestros resultados muestran que, para obtener un efectos sólido en el análisis estadístico de los resultados subjetivos, es necesario aumentar el número de sujetos de las pruebas claramente por encima de los tamaños de muestras propuestos por las normas y recomendaciones actuales. ABSTRACT Optimizing the Quality of Experience (QoE) of HTTP adaptive video streaming (HAS) is receiving increasing attention nowadays. The growth of interest is mainly caused by the fact that current HAS solutions are not QoE-driven, i.e. end-user quality perception is not integral part of the adaptation logic. However, obtaining the necessary reliable ground truths on HAS QoE faces substantial challenges, since the subjective video quality assessment methodologies as proposed by current standards are not well-suited for dealing with the time-varying quality properties that are characteristic for HAS. This thesis investigates the influence of dynamic quality adaptation on the QoE of streaming video by means of subjective evaluation approaches. Based on a comprehensive survey of related work on subjective HAS QoE assessment, the related challenges and open research questions are highlighted and discussed. As a result, two main research directions are selected for further investigation: analysis of the QoE impact of different technical adaptation parameters, and investigation of testing methodologies suitable for HAS QoE evaluation. In order to investigate related research issues and questions, a set of laboratory experiments have been conducted using different subjective testing methodologies. Our statistical analysis demonstrates that not all assumptions and claims reported in the literature are robust, particularly as regards the QoE impact of switching frequency, smooth vs. abrupt switching, and quality oscillation. On the other hand, our results confirm the influence of some other parameters such as chunk length and switching amplitude on perceived quality. We also show that taking the objective characteristics of the content into account can be beneficial to improve the adaptation viewing experience. In addition, all aforementioned findings are validated by means of an extensive cross-experimental analysis that involves external laboratory and crowdsourcing studies. Finally, to address the methodological aspects of subjective QoE testing, a comparison between the experimental results obtained from a (short stimuli-based) ACR standardized method and a semi-continuous method (developed for assessment of long video sequences) has been performed. In spite of observation of some differences, the result of statistical analysis does not show any significant effect of testing methodology. Similarly, although the influence of audio presence on evaluation of video-related degradations is perceived, no statistically significant effect of audio presence could be found. Motivating by this finding (no effect of testing method and audio presence), a subsequent analysis has been performed investigating the impact of performing multiple statistical comparisons on statistical levels of significance which increase the likelihood of Type-I errors (false positives). Our results show that in order to obtain a strong effect from the statistical analysis of the subjective results, it is necessary to increase the number of test subjects well beyond the sample sizes proposed by current quality assessment standards and recommendations.

Estimación del consumo de potencia en un terminal portátil multimedia basada en la PMU del procesador

Este proyecto se incluye en una línea de trabajo que tiene como objetivo final la optimización de la energía consumida por un dispositivo portátil multimedia mediante la aplicación de técnicas de control realimentado, a partir de una modificación dinámica de la frecuencia de trabajo del procesador y de su tensión de alimentación. La modificación de frecuencia y tensión se realiza a partir de la información de realimentación acerca de la potencia consumida por el dispositivo, lo que supone un problema ya que no suele ser posible la monitorización del consumo de potencia en dispositivos de estas características. Este es el motivo por el que se recurre a la estimación del consumo de potencia, utilizando para ello un modelo de predicción. A partir del número de veces que se producen ciertos eventos en el procesador del dispositivo, el modelo de predicción es capaz de obtener una estimación de la potencia consumida por dicho dispositivo. El trabajo llevado a cabo en este proyecto se centra en la implementación de un modelo de estimación de potencia en el kernel de Linux. La razón por la que la estimación se implementa en el sistema operativo es, en primer lugar para lograr un acceso directo a los contadores del procesador. En segundo lugar, para facilitar la modificación de frecuencia y tensión, una vez obtenida la estimación de potencia, ya que esta también se realiza desde el sistema operativo. Otro motivo para implementar la estimación en el sistema operativo, es que la estimación debe ser independiente de las aplicaciones de usuario. Además, el proceso de estimación se realiza de forma periódica, lo que sería difícil de lograr si no se trabajase desde el sistema operativo. Es imprescindible que la estimación se haga de forma periódica ya que al ser dinámica la modificación de frecuencia y tensión que se pretende implementar, se necesita conocer el consumo de potencia del dispositivo en todo momento. Cabe destacar también, que los algoritmos de control se tienen que diseñar sobre un patrón periódico de actuación. El modelo de estimación de potencia funciona de manera específica para el perfil de consumo generado por una única aplicación determinada, que en este caso es un decodificador de vídeo. Sin embargo, es necesario que funcione de la forma más precisa posible para cada una de las frecuencias de trabajo del procesador, y para el mayor número posible de secuencias de vídeo. Esto es debido a que las sucesivas estimaciones de potencia se pretenden utilizar para llevar a cabo la modificación dinámica de frecuencia, por lo que el modelo debe ser capaz de continuar realizando las estimaciones independientemente de la frecuencia con la que esté trabajando el dispositivo. Para valorar la precisión del modelo de estimación se toman medidas de la potencia consumida por el dispositivo a las distintas frecuencias de trabajo durante la ejecución del decodificador de vídeo. Estas medidas se comparan con las estimaciones de potencia obtenidas durante esas mismas ejecuciones, obteniendo de esta forma el error de predicción cometido por el modelo y realizando las modificaciones y ajustes oportunos en el mismo. ABSTRACT. This project is included in a work line which tries to optimize consumption of handheld multimedia devices by the application of feedback control techniques, from a dynamic modification of the processor work frequency and its voltage. The frequency and voltage modification is performed depending on the feedback information about the device power consumption. This is a problem because normally it is not possible to monitor the power consumption on this kind of devices. This is the reason why a power consumption estimation is used instead, which is obtained from a prediction model. Using the number of times some events occur on the device processor, the prediction model is able to obtain a power consumption estimation of this device. The work done in this project focuses on the implementation of a power estimation model in the Linux kernel. The main reason to implement the estimation in the operating system is to achieve a direct access to the processor counters. The second reason is to facilitate the frequency and voltage modification, because this modification is also done from the operating system. Another reason to implement the estimation in the operating system is because the estimation must be done apart of the user applications. Moreover, the estimation process is done periodically, what is difficult to obtain outside the operating system. It is necessary to make the estimation in a periodic way because the frequency and voltage modification is going to be dynamic, so it needs to know the device power consumption at every time. Also, it is important to say that the control algorithms have to be designed over a periodic pattern of action. The power estimation model works specifically for the consumption profile generated by a single application, which in this case is a video decoder. Nevertheless, it is necessary that the model works as accurate as possible for each frequency available on the processor, and for the greatest number of video sequences. This is because the power estimations are going to be used to modify dynamically the frequency, so the model must be able to work independently of the device frequency. To value the estimation model precision, some measurements of the device power consumption are taken at different frequencies during the video decoder execution. These measurements are compared with the power estimations obtained during that execution, getting the prediction error committed by the model, and if it is necessary, making modifications and settings on this model.

Development of a hand-gesture recognition system for human-computer interaction

The aim of this Master Thesis is the analysis, design and development of a robust and reliable Human-Computer Interaction interface, based on visual hand-gesture recognition. The implementation of the required functions is oriented to the simulation of a classical hardware interaction device: the mouse, by recognizing a specific hand-gesture vocabulary in color video sequences. For this purpose, a prototype of a hand-gesture recognition system has been designed and implemented, which is composed of three stages: detection, tracking and recognition. This system is based on machine learning methods and pattern recognition techniques, which have been integrated together with other image processing approaches to get a high recognition accuracy and a low computational cost. Regarding pattern recongition techniques, several algorithms and strategies have been designed and implemented, which are applicable to color images and video sequences. The design of these algorithms has the purpose of extracting spatial and spatio-temporal features from static and dynamic hand gestures, in order to identify them in a robust and reliable way. Finally, a visual database containing the necessary vocabulary of gestures for interacting with the computer has been created.

Female preference for swords in Xiphophorus helleri reflects a bias for large apparent size

Swordtail fish (Poeciliidae: genus Xiphophorus) are a paradigmatic case of sexual selection by sensory exploitation. Female preference for males with a conspicuous “sword” ornament is ancestral, suggesting that male morphology has evolved in response to a preexisting bias. The perceptual mechanisms underlying female mate choice have not been identified, complicating efforts to understand the selection pressures acting on ornament design. We consider two alternative models of receiver behavior, each consistent with previous results. Females could respond either to specific characteristics of the sword or to more general cues, such as the apparent size of potential mates. We showed female swordtails a series of computer-altered video sequences depicting a courting male. Footage of an intact male was preferred strongly to otherwise identical sequences in which portions of the sword had been deleted selectively, but a disembodied courting sword was less attractive than an intact male. There was no difference between responses to an isolated sword and to a swordless male of comparable length, or between an isolated sword and a homogenous background. Female preference for a sworded male was abolished by enlarging the image of a swordless male to compensate for the reduction in length caused by removing the ornament. This pattern of results is consistent with mate choice being mediated by a general preference for large males rather than by specific characters. Similar processes may account for the evolution of exaggerated traits in other systems.

Use of subpixel techniques in pocket cameras to measure vibrations and displacements

Presentación oral SPIE Photonics Europe, Brussels, 16-19 April 2012.

Fetal endoscopic telesurgery using an Internet protocol connection: clinical and technical challenges

Until recently, fetoscopic laser surgery to seal the placental anastomoses that cause severe twin-to-twin transfusion syndrome has been available in only a few centres worldwide. The technique typically takes a long time to learn. We have used a dedicated Internet Protocol (IP) connection for tele-education to assist the introduction of fetoscopic laser surgery to Australia. During the implementation of the international telemedicine link, there were multiple clinical and technical problems, which were eventually overcome. The quality of images and of video-sequences was comparable to that supported by an ISDN connection. Pictures of live surgery performed by an expert in Florida, USA, were transmitted and viewed by a novice team in Brisbane, Australia. The Australian team has performed 19 fetoscopic laser operations to date. Preliminary results are comparable to those from centres that have performed over 100 procedures.