Comparison of NDVI fields obtained from different remote sensors

Satellite image data have become an important source of information for monitoring vegetation and mapping land cover at several scales. Beside this, the distribution and phenology of vegetation is largely associated with climate, terrain characteristics and human activity. Various vegetation indices have been developed for qualitative and quantitative assessment of vegetation using remote spectral measurements. In particular, sensors with spectral bands in the red (RED) and near-infrared (NIR) lend themselves well to vegetation monitoring and based on them [(NIR - RED) / (NIR + RED)] Normalized Difference Vegetation Index (NDVI) has been widespread used. Given that the characteristics of spectral bands in RED and NIR vary distinctly from sensor to sensor, NDVI values based on data from different instruments will not be directly comparable. The spatial resolution also varies significantly between sensors, as well as within a given scene in the case of wide-angle and oblique sensors. As a result, NDVI values will vary according to combinations of the heterogeneity and scale of terrestrial surfaces and pixel footprint sizes. Therefore, the question arises as to the impact of differences in spectral and spatial resolutions on vegetation indices like the NDVI and their interpretation as a drought index. During 2012 three locations (at Salamanca, Granada and Córdoba) were selected and a periodic pasture monitoring and botanic composition were achieved. Daily precipitation, temperature and monthly soil water content were measurement as well as fresh and dry pasture weight. At the same time, remote sensing images were capture by DEIMOS-1 and MODIS of the chosen places. DEIMOS-1 is based on the concept Microsat-100 from Surrey. It is conceived for obtaining Earth images with a good enough resolution to study the terrestrial vegetation cover (20x20 m), although with a great range of visual field (600 km) in order to obtain those images with high temporal resolution and at a reduced cost. By contranst, MODIS images present a much lower spatial resolution (500x500 m). The aim of this study is to establish a comparison between two different sensors in their NDVI values at different spatial resolutions. Acknowledgements. This work was partially supported by ENESA under project P10 0220C-823. Funding provided by Spanish Ministerio de Ciencia e Innovación (MICINN) through project no. MTM2009-14621 and i-MATH No. CSD2006-00032 is greatly appreciated.

Managing Industrial Simulator Visual Databases Using Geographic Information Systems

Geographic Information Systems are developed to handle enormous volumes of data and are equipped with numerous functionalities intended to capture, store, edit, organise, process and analyse or represent the geographically referenced information. On the other hand, industrial simulators for driver training are real-time applications that require a virtual environment, either geospecific, geogeneric or a combination of the two, over which the simulation programs will be run. In the final instance, this environment constitutes a geographic location with its specific characteristics of geometry, appearance, functionality, topography, etc. The set of elements that enables the virtual simulation environment to be created and in which the simulator user can move, is usually called the Visual Database (VDB). The main idea behind the work being developed approaches a topic that is of major interest in the field of industrial training simulators, which is the problem of analysing, structuring and describing the virtual environments to be used in large driving simulators. This paper sets out a methodology that uses the capabilities and benefits of Geographic Information Systems for organising, optimising and managing the visual Database of the simulator and for generally enhancing the quality and performance of the simulator.

Generación y Gestión Optimizadas de la Base de Datos de un Visual para su Implementación en un Simulador de Formación

Los Sistemas de Información Geográfica están desarrollados para gestionar grandes volúmenes de datos, y disponen de numerosas funcionalidades orientadas a la captura, almacenamiento, edición, organización, procesado, análisis, o a la representación de información geográficamente referenciada. Por otro lado, los simuladores industriales para entrenamiento en tareas de conducción son aplicaciones en tiempo real que necesitan de un entorno virtual, ya sea geoespecífico, geogenérico, o combinación de ambos tipos, sobre el cual se ejecutarán los programas propios de la simulación. Este entorno, en última instancia, constituye un lugar geográfico, con sus características específicas geométricas, de aspecto, funcionales, topológicas, etc. Al conjunto de elementos que permiten la creación del entorno virtual de simulación dentro del cual se puede mover el usuario del simulador se denomina habitualmente Base de Datos del Visual (BDV). La idea principal del trabajo que se desarrolla aborda un tema del máximo interés en el campo de los simuladores industriales de formación, como es el problema que presenta el análisis, la estructuración, y la descripción de los entornos virtuales a emplear en los grandes simuladores de conducción. En este artículo se propone una metodología de trabajo en la que se aprovechan las capacidades y ventajas de los Sistemas de Información Geográfica para organizar, optimizar y gestionar la base de datos visual del simulador, y para mejorar la calidad y el rendimiento del simulador en general. ABSTRACT Geographic Information Systems are developed to handle enormous volumes of data and are equipped with numerous functionalities intended to capture, store, edit, organise, process and analyse or represent the geographically referenced information. On the other hand, industrial simulators for driver training are real-time applications that require a virtual environment, either geospecific, geogeneric or a combination of the two, over which the simulation programs will be run. In the final instance, this environment constitutes a geographic location with its specific characteristics of geometry, appearance, functionality, topography, etc. The set of elements that enables the virtual simulation environment to be created and in which the simulator user can move, is usually called the Visual Database (VDB). The main idea behind the work being developed approaches a topic that is of major interest in the field of industrial training simulators, which is the problem of analysing, structuring and describing the virtual environments to be used in large driving simulators. This paper sets out a methodology that uses the capabilities and benefits of Geographic Information Systems for organising, optimising and managing the visual Database of the simulator and for generally enhancing the quality and performance of the simulator.

Aesthetic appreciation: event-related field and time-frequency analyses

Improvements in neuroimaging methods have afforded significant advances in our knowledge of the cognitive and neural foundations of aesthetic appreciation. We used magnetoencephalography (MEG) to register brain activity while participants decided about the beauty of visual stimuli. The data were analyzed with event-related field (ERF) and Time-Frequency (TF) procedures. ERFs revealed no significant differences between brain activity related with stimuli rated as “beautiful” and “not beautiful.” TF analysis showed clear differences between both conditions 400 ms after stimulus onset. Oscillatory power was greater for stimuli rated as “beautiful” than those regarded as “not beautiful” in the four frequency bands (theta, alpha, beta, and gamma). These results are interpreted in the frame of synchronization studies.

On subjective impressions or how to put numbers to visual illusions

This paper presents a simple theory to analyze some of the more common visual illusions. The reported mathematical model is able to give some numerical results concerning well known phenomena as the Zollner, Muller-Lyer or Wundt illusions. We present two different approaches, the first one related with the symmetrical operations present in each image and the second one concerning a proposed vector field related with the lines present at the image

A visual framework to accelerate knowledge discovery based on dimensionality reduction minimizing degradation of quality

Tradicionalmente, el uso de técnicas de análisis de datos ha sido una de las principales vías para el descubrimiento de conocimiento oculto en grandes cantidades de datos, recopilados por expertos en diferentes dominios. Por otra parte, las técnicas de visualización también se han usado para mejorar y facilitar este proceso. Sin embargo, existen limitaciones serias en la obtención de conocimiento, ya que suele ser un proceso lento, tedioso y en muchas ocasiones infructífero, debido a la dificultad de las personas para comprender conjuntos de datos de grandes dimensiones. Otro gran inconveniente, pocas veces tenido en cuenta por los expertos que analizan grandes conjuntos de datos, es la degradación involuntaria a la que someten a los datos durante las tareas de análisis, previas a la obtención final de conclusiones. Por degradación quiere decirse que los datos pueden perder sus propiedades originales, y suele producirse por una reducción inapropiada de los datos, alterando así su naturaleza original y llevando en muchos casos a interpretaciones y conclusiones erróneas que podrían tener serias implicaciones. Además, este hecho adquiere una importancia trascendental cuando los datos pertenecen al dominio médico o biológico, y la vida de diferentes personas depende de esta toma final de decisiones, en algunas ocasiones llevada a cabo de forma inapropiada. Ésta es la motivación de la presente tesis, la cual propone un nuevo framework visual, llamado MedVir, que combina la potencia de técnicas avanzadas de visualización y minería de datos para tratar de dar solución a estos grandes inconvenientes existentes en el proceso de descubrimiento de información válida. El objetivo principal es hacer más fácil, comprensible, intuitivo y rápido el proceso de adquisición de conocimiento al que se enfrentan los expertos cuando trabajan con grandes conjuntos de datos en diferentes dominios. Para ello, en primer lugar, se lleva a cabo una fuerte disminución en el tamaño de los datos con el objetivo de facilitar al experto su manejo, y a la vez preservando intactas, en la medida de lo posible, sus propiedades originales. Después, se hace uso de efectivas técnicas de visualización para representar los datos obtenidos, permitiendo al experto interactuar de forma sencilla e intuitiva con los datos, llevar a cabo diferentes tareas de análisis de datos y así estimular visualmente su capacidad de comprensión. De este modo, el objetivo subyacente se basa en abstraer al experto, en la medida de lo posible, de la complejidad de sus datos originales para presentarle una versión más comprensible, que facilite y acelere la tarea final de descubrimiento de conocimiento. MedVir se ha aplicado satisfactoriamente, entre otros, al campo de la magnetoencefalografía (MEG), que consiste en la predicción en la rehabilitación de lesiones cerebrales traumáticas (Traumatic Brain Injury (TBI) rehabilitation prediction). Los resultados obtenidos demuestran la efectividad del framework a la hora de acelerar y facilitar el proceso de descubrimiento de conocimiento sobre conjuntos de datos reales. ABSTRACT Traditionally, the use of data analysis techniques has been one of the main ways of discovering knowledge hidden in large amounts of data, collected by experts in different domains. Moreover, visualization techniques have also been used to enhance and facilitate this process. However, there are serious limitations in the process of knowledge acquisition, as it is often a slow, tedious and many times fruitless process, due to the difficulty for human beings to understand large datasets. Another major drawback, rarely considered by experts that analyze large datasets, is the involuntary degradation to which they subject the data during analysis tasks, prior to obtaining the final conclusions. Degradation means that data can lose part of their original properties, and it is usually caused by improper data reduction, thereby altering their original nature and often leading to erroneous interpretations and conclusions that could have serious implications. Furthermore, this fact gains a trascendental importance when the data belong to medical or biological domain, and the lives of people depends on the final decision-making, which is sometimes conducted improperly. This is the motivation of this thesis, which proposes a new visual framework, called MedVir, which combines the power of advanced visualization techniques and data mining to try to solve these major problems existing in the process of discovery of valid information. Thus, the main objective is to facilitate and to make more understandable, intuitive and fast the process of knowledge acquisition that experts face when working with large datasets in different domains. To achieve this, first, a strong reduction in the size of the data is carried out in order to make the management of the data easier to the expert, while preserving intact, as far as possible, the original properties of the data. Then, effective visualization techniques are used to represent the obtained data, allowing the expert to interact easily and intuitively with the data, to carry out different data analysis tasks, and so visually stimulating their comprehension capacity. Therefore, the underlying objective is based on abstracting the expert, as far as possible, from the complexity of the original data to present him a more understandable version, thus facilitating and accelerating the task of knowledge discovery. MedVir has been succesfully applied to, among others, the field of magnetoencephalography (MEG), which consists in predicting the rehabilitation of Traumatic Brain Injury (TBI). The results obtained successfully demonstrate the effectiveness of the framework to accelerate and facilitate the process of knowledge discovery on real world datasets.

Merit function for the evaluation of color uniformity in the far field of LED spot lights

The scope of the present paper is the derivation of a merit function which predicts the visual perception of LED spot lights. The color uniformity level Usl is described by a linear regression function of the spatial color distribution in the far field. Hereby, the function is derived from four basic functions. They describe the color uniformity of spot lights through different features. The result is a reliable prediction for the perceived color uniformity in spot lights. A human factor experiment was performed to evaluate the visual preferences for colors and patterns. A perceived rank order was derived from the subjects’ answers and compared with the four basic functions. The correlation between the perceived rank order and the basic functions was calculated resulting in the definition of the merit function Usl. The application of this function is shown by a comparison of visual evaluations and measurements of LED retrofit spot lamps. The results enable a prediction of color uniformity levels of simulations and measurements concerning the visual perception. The function provides a possibility to evaluate the far field of spot lights without individual subjective judgment. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Color uniformity in spotligths - visual perception and system design

La iluminación con diodos emisores de luz (LED) está reemplazando cada vez en mayor medida a las fuentes de luz tradicionales. La iluminación LED ofrece ventajas en eficiencia, consumo de energía, diseño, tamaño y calidad de la luz. Durante más de 50 años, los investigadores han estado trabajando en mejoras LED. Su principal relevancia para la iluminación está aumentando rápidamente. Esta tesis se centra en un campo de aplicación importante, como son los focos. Se utilizan para enfocar la luz en áreas definidas, en objetos sobresalientes en condiciones profesionales. Esta iluminación de alto rendimiento requiere una calidad de luz definida, que incluya temperaturas ajustables de color correlacionadas (CCT), de alto índice de reproducción cromática (CRI), altas eficiencias, y colores vivos y brillantes. En el paquete LED varios chips de diferentes colores (rojo, azul, fósforo convertido) se combinan para cumplir con la distribución de energía espectral con alto CRI. Para colimar la luz en los puntos concretos deseados con un ángulo de emisión determinado, se utilizan blancos sintonizables y diversos colores de luz y ópticas secundarias. La combinación de una fuente LED de varios colores con elementos ópticos puede causar falta de homogeneidad cromática en la distribución espacial y angular de la luz, que debe resolverse en el diseño óptico. Sin embargo, no hay necesidad de uniformidad perfecta en el punto de luz debido al umbral en la percepción visual del ojo humano. Por lo tanto, se requiere una descripción matemática del nivel de uniformidad del color con respecto a la percepción visual. Esta tesis está organizada en siete capítulos. Después de un capítulo inicial que presenta la motivación que ha guiado la investigación de esta tesis, en el capítulo 2 se presentan los fundamentos científicos de la uniformidad del color en luces concentradas, como son: el espacio de color aplicado CIELAB, la percepción visual del color, los fundamentos de diseño de focos respecto a los motores de luz y ópticas no formadoras de imágenes, y los últimos avances en la evaluación de la uniformidad del color en el campo de los focos. El capítulo 3 desarrolla diferentes métodos para la descripción matemática de la distribución espacial del color en un área definida, como son la diferencia de color máxima, la desviación media del color, el gradiente de la distribución espacial de color, así como la suavidad radial y axial. Cada función se refiere a los diferentes factores que influyen en la visión, los cuales necesitan un tratamiento distinto que el de los datos que se tendrán en cuenta, además de funciones de ponderación que pre- y post-procesan los datos simulados o medidos para la reducción del ruido, la luminancia de corte, la aplicación de la ponderación de luminancia, la función de sensibilidad de contraste, y la función de distribución acumulativa. En el capítulo 4, se obtiene la función de mérito Usl para la estimación de la uniformidad del color percibida en focos. Se basó en los resultados de dos conjuntos de experimentos con factor humano realizados para evaluar la percepción visual de los sujetos de los patrones de focos típicos. El primer experimento con factor humano dio lugar al orden de importancia percibida de los focos. El orden de rango percibido se utilizó para correlacionar las descripciones matemáticas de las funciones básicas y la función ponderada sobre la distribución espacial del color, que condujo a la función Usl. El segundo experimento con factor humano probó la percepción de los focos bajo condiciones ambientales diversas, con el objetivo de proporcionar una escala absoluta para Usl, para poder así sustituir la opinión subjetiva personal de los individuos por una función de mérito estandarizada. La validación de la función Usl se presenta en relación con el alcance de la aplicación y condiciones, así como las limitaciones y restricciones que se realizan en el capítulo 5. Se compararon los datos medidos y simulados de varios sistemas ópticos. Se discuten los campos de aplicación , así como validaciones y restricciones de la función. El capítulo 6 presenta el diseño del sistema de focos y su optimización. Una evaluación muestra el análisis de sistemas basados en el reflector y la lente TIR. Los sistemas ópticos simulados se comparan en la uniformidad del color Usl, sensibilidad a las sombras coloreadas, eficiencia e intensidad luminosa máxima. Se ha comprobado que no hay un sistema único que obtenga los mejores resultados en todas las categorías, y que una excelente uniformidad de color se pudo alcanzar por la conjunción de dos sistemas diferentes. Finalmente, el capítulo 7 presenta el resumen de esta tesis y la perspectiva para investigar otros aspectos. ABSTRACT Illumination with light-emitting diodes (LED) is more and more replacing traditional light sources. They provide advantages in efficiency, energy consumption, design, size and light quality. For more than 50 years, researchers have been working on LED improvements. Their main relevance for illumination is rapidly increasing. This thesis is focused on one important field of application which are spotlights. They are used to focus light on defined areas, outstanding objects in professional conditions. This high performance illumination required a defined light quality including tunable correlated color temperatures (CCT), high color rendering index (CRI), high efficiencies and bright, vivid colors. Several differently colored chips (red, blue, phosphor converted) in the LED package are combined to meet spectral power distribution with high CRI, tunable white and several light colors and secondary optics are used to collimate the light into the desired narrow spots with defined angle of emission. The combination of multi-color LED source and optical elements may cause chromatic inhomogeneities in spatial and angular light distribution which needs to solved at the optical design. However, there is no need for perfect uniformity in the spot light due to threshold in visual perception of human eye. Therefore, a mathematical description of color uniformity level with regard to visual perception is required. This thesis is organized seven seven chapters. After an initial one presenting the motivation that has guided the research of this thesis, Chapter 2 introduces the scientific basics of color uniformity in spot lights including: the applied color space CIELAB, the visual color perception, the spotlight design fundamentals with regards to light engines and nonimaging optics, and the state of the art for the evaluation of color uniformity in the far field of spotlights. Chapter 3 develops different methods for mathematical description of spatial color distribution in a defined area, which are the maximum color difference, the average color deviation, the gradient of spatial color distribution as well as the radial and axial smoothness. Each function refers to different visual influencing factors, and they need different handling of data be taken into account, along with weighting functions which pre- and post-process the simulated or measured data for noise reduction, luminance cutoff, the implementation of luminance weighting, contrast sensitivity function, and cumulative distribution function. In chapter 4, the merit function Usl for the estimation of the perceived color uniformity in spotlights is derived. It was based on the results of two sets of human factor experiments performed to evaluate the visual perception of typical spotlight patterns by subjects. The first human factor experiment resulted in the perceived rank order of the spotlights. The perceived rank order was used to correlate the mathematical descriptions of basic functions and weighted function concerning the spatial color distribution, which lead to the Usl function. The second human factor experiment tested the perception of spotlights under varied environmental conditions, with to objective to provide an absolute scale for Usl, so the subjective personal opinion of individuals could be replaced by a standardized merit function. The validation of the Usl function is presented concerning the application range and conditions as well as limitations and restrictions in carried out in chapter 5. Measured and simulated data of various optical several systems were compared. Fields of applications are discussed as well as validations and restrictions of the function. Chapter 6 presents spotlight system design and their optimization. An evaluation shows the analysis of reflector-based and TIR lens systems. The simulated optical systems are compared in color uniformity Usl , sensitivity to colored shadows, efficiency, and peak luminous intensity. It has been found that no single system which performed best in all categories, and that excellent color uniformity could be reached by two different system assemblies. Finally, chapter 7 summarizes the conclusions of the present thesis and an outlook for further investigation topics.

Online Learning-based Robust Visual Tracking for Autonomous Landing of Unmanned Aerial Vehicles

Autonomous landing is a challenging and important technology for both military and civilian applications of Unmanned Aerial Vehicles (UAVs). In this paper, we present a novel online adaptive visual tracking algorithm for UAVs to land on an arbitrary field (that can be used as the helipad) autonomously at real-time frame rates of more than twenty frames per second. The integration of low-dimensional subspace representation method, online incremental learning approach and hierarchical tracking strategy allows the autolanding task to overcome the problems generated by the challenging situations such as significant appearance change, variant surrounding illumination, partial helipad occlusion, rapid pose variation, onboard mechanical vibration (no video stabilization), low computational capacity and delayed information communication between UAV and Ground Control Station (GCS). The tracking performance of this presented algorithm is evaluated with aerial images from real autolanding flights using manually- labelled ground truth database. The evaluation results show that this new algorithm is highly robust to track the helipad and accurate enough for closing the vision-based control loop.

Online Learning-based Robust Visual Tracking for Autonomous Landing of Unmanned Aerial Vehicles

Autonomous landing is a challenging and important technology for both military and civilian applications of Unmanned Aerial Vehicles (UAVs). In this paper, we present a novel online adaptive visual tracking algorithm for UAVs to land on an arbitrary field (that can be used as the helipad) autonomously at real-time frame rates of more than twenty frames per second. The integration of low-dimensional subspace representation method, online incremental learning approach and hierarchical tracking strategy allows the autolanding task to overcome the problems generated by the challenging situations such as significant appearance change, variant surrounding illumination, partial helipad occlusion, rapid pose variation, onboard mechanical vibration (no video stabilization), low computational capacity and delayed information communication between UAV and Ground Control Station (GCS). The tracking performance of this presented algorithm is evaluated with aerial images from real autolanding flights using manually- labelled ground truth database. The evaluation results show that this new algorithm is highly robust to track the helipad and accurate enough for closing the vision-based control loop.

Luz industrial e imagen tecnificada: de Moholy Nagy al C.A.V.S. (Center for Advanced Visual Studies)

El desarrollo de la tecnología de la luz implicará la transformación de la vida social, cultural y económica. Tanto las consideraciones espaciales del Movimiento Moderno, como los efectos producidos por la segunda Guerra Mundial, tendrán efectos visibles en las nuevas configuraciones espaciales y en la relación simbiótica y recíproca que se dará entre ideología y tecnología. La transformación en la comprensión de la articulación espacial, asociada al desarrollo tecnológico, afectará al modo en que este espacio es experimentado y percibido. El espacio expositivo y el espacio escénico se convertirán en laboratorio práctico donde desarrollar y hacer comprensible todo el potencial ilusorio de la luz, la proyección y la imagen, como parámetros modificadores y dinamizadores del espacio arquitectónico. Esta experimentación espacial estará precedida por la investigación y creación conceptual en el mundo plástico, donde los nuevos medios mecánicos serán responsables de la construcción de una nueva mirada moderna mediatizada por los elementos técnicos. La experimentación óptica, a través de la fotografía, el cine, o el movimiento de la luz y su percepción, vinculada a nuevos modos de representación y comunicación, se convertirá en elemento fundamental en la configuración espacial. Este ámbito de experimentación se hará patente en la Escuela de la Bauhaus, de la mano de Gropius, Schlemmer o Moholy Nagy entre otros; tanto en reflexiones teóricas como en el desarrollo de proyectos expositivos, arquitectónicos o teatrales, que evolucionarán en base a la tecnología y la modificación de la relación con el espectador. El espacio expositivo y el espacio escénico se tomarán como oportunidad de investigación espacial y de análisis de los modos de percepción, convirtiéndose en lugares de experimentación básicos para el aprendizaje. El teatro se postula como punto de encuentro entre el arte y la técnica, cobrando especial importancia la intersección con otras disciplinas en la definición espacial. Las múltiples innovaciones técnicas ligadas a los nuevos fundamentos teatrales en la modificación de la relación con la escena, que se producen a principios del siglo XX, tendrán como consecuencia la transformación del espacio en un espacio dinámico, tanto física como perceptivamente, que dará lugar a nuevas concepciones espaciales, muchas de ellas utópicas. La luz, la proyección y la creación de ilusión en base a estímulos visuales y sonoros, aparecen como elementos proyectuales efímeros e inmateriales, que tendrán una gran incidencia en el espacio y su modo de ser experimentado. La implicación de la tecnología en el arte conllevará modificaciones en la visualización, así como en la configuración espacial de los espacios destinados a esta. Destacaremos como propuesta el Teatro Total de Walter Gropius, en cuyo desarrollo se recogen de algún modo las experiencias espaciales y las investigaciones desarrolladas sobre la estructura formal de la percepción realizadas por Moholy Nagy, además de los conceptos acerca del espacio escénico desarrollados en el taller de Teatro de la Bauhaus por Oskar Schlemmer. En el Teatro Total, Gropius incorporará su propia visión de cuestiones que pertenecen a la tradición de la arquitectura teatral y las innovaciones conceptuales que estaban teniendo lugar desde finales del s.XIX, tales como la participación activa del público o la superación entre escena y auditorio, estableciendo en el proyecto una nueva relación perceptual entre sala, espectáculo y espectador; aumentando la sensación de inmersión, a través del uso de la física, la óptica, y la acústica, creando una energía concéntrica capaz de extenderse en todas direcciones. El Teatro Total será uno de los primeros ejemplos en los que desde el punto de partida del proyecto, se conjuga la imagen como elemento comunicativo con la configuración espacial. Las nuevas configuraciones escénicas tendrán como premisa de desarrollo la capacidad de transformación tanto perceptiva, como física. En la segunda mitad del s.XX, la creación de centros de investigación como el CAVS (The Center for Advanced Visual Studies,1967), o el EAT (Experiments in Art and Technology, 1966), favorecerán la colaboración interdisciplinar entre arte y ciencia, implicando a empresas de carácter tecnológico, como Siemens, HP, IBM o Philips, facilitando soporte técnico y económico para el desarrollo de nuevos sistemas. Esta colaboración interdisciplinar dará lugar a una serie de intervenciones espaciales que tendrán su mayor visibilidad en algunas Exposiciones Universales. El resultado será, en la mayoría de los casos, la creación de espacios de carácter inmersivo, donde se establecerá una relación simbiótica entre espacio, imagen, sonido, y espectador. La colocación del espectador en el centro de la escena y la disposición dinámica de imagen y sonido, crearán una particular narrativa espacial no lineal, concebida para la experiencia. Desde las primeras proyecciones de cine a la pantalla múltiple de los Eames, las técnicas espaciales de difusión del sonido en Stockhausen, o los experimentos con el movimiento físico interactivo, la imagen, la luz en movimiento y el sonido, quedan inevitablemente convertidos en material arquitectónico. ABSTRACT. Light technology development would lead to a social, cultural and economic transformation. Both spatial consideration of “Modern Movement” and Second World War effects on technology, would have a visible aftereffect on spatial configuration and on the symbiotic and mutual relationship between ideology & technology. Comprehension adjustment on the articulation of space together with technology development, would impact on how space is perceived and felt. Exhibition space and scenic space would turn into a laboratory where developing and making comprehensive all illusory potential of light, projection and image. These new parameters would modify and revitalize the architectonic space. as modifying and revitalizing parameters of architectonic space. Spatial experimentation would be preceded by conceptual creation and investigation on the sculptural field, where new mechanic media would be responsible for a fresh and modern look influenced by technical elements. Optical experimentation, through photography, cinema or light movement and its perception, would turn into essential components for spatial arrangement linked to new ways of performance and communication. This experimentation sphere would be clear at The Bauhaus School, by the hand of Gropius, Schlemmer or Moholy Nag among others; in theoretical, theatrical or architectural performance’s projects, that would evolve based on technology and also based on the transformation of the relationship with the observer. Exhibition and perfor-mance areas would be taken as opportunities of spatial investigation and for the analysis of the different ways of perception, thus becoming key places for learning. Theater is postulated as a meeting point between art and technique, taking on a new significance at its intersection with other disciplines working with spatial definition too. The multiple innovation techniques linked to the new foundations for the theater regarding stage relation, would have as a consequence the regeneration of the space. Space would turn dynamic, both physically and perceptibly, bringing innovative spatial conceptions, many of them unrealistic. Light, projection and illusory creation based on sound and visual stimulus would appear as intangible and momentary design components, which would have a great impact on the space and on the way it is experienced. Implication of technology in art would bring changes on the observer as well as on the spatial configuration of the art spaces2. It would stand out as a proposal Walter Groupis Total Theater, whose development would include somehow the spatial experiments and studies about formal structure of perception accomplished by Moholy Nagy besides the concepts regarding stage space enhanced at the Bauhaus Theater Studio by Oskar Schlemmer. Within Total Theater, Groupis would incorporate his own view about traditional theatric architecture and conceptual innovations that were taking place since the end of the nineteenth century, such as active audience participation or the diffusing limits between scene and audience, establishing a new perception relationship between auditorium, performance and audience, improving the feeling of immersion through the use of physics, optics and acoustics, creating a concentric energy capable of spreading in all directions. Total Theater would be one of the first example in which, from the beginning of the Project, image is combined as a communicating element with the spatial configuration. As a premise of development, new stage arrangement would have the capacity of transformation, both perceptive and physically. During the second half or the twentieth century, the creation of investigation centers such as CAVS (Center for Advanced Visual Studies, 1967) or EAT (Experiments in Art and Technology, 1966), would help to the interdisciplinary collaboration between art and science, involving technology companies like Siemens, HP, IBM or Philips, providing technical and economic support to the development of new systems. This interdisciplinary collaboration would give room to a series of spatial interventions which would have visibility in some Universal Exhibitions. The result would be, in most cases, the creation of immersive character spaces, where a symbiotic relationship would be stablished between space, image, sound and audience. The new location of the audience in the middle of the display, together with the dynamic arrangement of sound and image would create a particular, no lineal narrative conceived to be experienced. Since the first cinema projections, the multiple screen of Eames, the spatial techniques for sound dissemination at Stockhausen or the interactive physical movement experimentation, image, motion light and sound would turn inevitably into architectural material.

Multiple feature points representation in target localization of wireless visual sensor networks

This paper discusses the target localization problem in wireless visual sensor networks. Additive noises and measurement errors will affect the accuracy of target localization when the visual nodes are equipped with low-resolution cameras. In the goal of improving the accuracy of target localization without prior knowledge of the target, each node extracts multiple feature points from images to represent the target at the sensor node level. A statistical method is presented to match the most correlated feature point pair for merging the position information of different sensor nodes at the base station. Besides, in the case that more than one target exists in the field of interest, a scheme for locating multiple targets is provided. Simulation results show that, our proposed method has desirable performance in improving the accuracy of locating single target or multiple targets. Results also show that the proposed method has a better trade-off between camera node usage and localization accuracy.