Space-time ocean wave measurement using variational stereo vision systems

Remote sensing imaging systems for the measurement of oceanic sea states have recently attracted renovated attention. Imaging technology is economical, non-invasive and enables a better understanding of the space-time dynamics of ocean waves over an area rather than at selected point locations of previous monitoring methods (buoys, wave gauges, etc.). We present recent progress in space-time measurement of ocean waves using stereo vision systems on offshore platforms. Both traditional disparity-based systems and modern elevation-based ones are presented in a variational optimization framework: the main idea is to pose the stereoscopic reconstruction problem of the surface of the ocean in a variational setting and design an energy functional whose minimizer is the desired temporal sequence of wave heights. The functional combines photometric observations as well as spatial and temporal smoothness priors. Disparity methods estimate the disparity between images as an intermediate step toward retrieving the depth of the waves with respect to the cameras, whereas elevation methods estimate the ocean surface displacements directly in 3-D space. Both techniques are used to measure ocean waves from real data collected at offshore platforms in the Black Sea (Crimean Peninsula, Ukraine) and the Northern Adriatic Sea (Venice coast, Italy). Then, the statistical and spectral properties of the resulting observed waves are analyzed. We show the advantages and disadvantages of the presented stereo vision systems and discuss the improvement of their performance in critical issues such as the robustness of the camera calibration in spite of undesired variations of the camera parameters.

Offshore remote sensing of the ocean by stereo vision systems

In recent years, remote sensing imaging systems for the measurement of oceanic sea states have attracted renovated attention. Imaging technology is economical, non-invasive and enables a better understanding of the space-time dynamics of ocean waves over an area rather than at selected point locations of previous monitoring methods (buoys, wave gauges, etc.). We present recent progress in space-time measurement of ocean waves using stereo vision systems on offshore platforms, which focus on sea states with wavelengths in the range of 0.01 m to 1 m. Both traditional disparity-based systems and modern elevation-based ones are presented in a variational optimization framework: the main idea is to pose the stereoscopic reconstruction problem of the surface of the ocean in a variational setting and design an energy functional whose minimizer is the desired temporal sequence of wave heights. The functional combines photometric observations as well as spatial and temporal smoothness priors. Disparity methods estimate the disparity between images as an intermediate step toward retrieving the depth of the waves with respect to the cameras, whereas elevation methods estimate the ocean surface displacements directly in 3-D space. Both techniques are used to measure ocean waves from real data collected at offshore platforms in the Black Sea (Crimean Peninsula, Ukraine) and the Northern Adriatic Sea (Venice coast, Italy). Then, the statistical and spectral properties of the resulting observed waves are analyzed. We show the advantages and disadvantages of the presented stereo vision systems and discuss future lines of research to improve their performance in critical issues such as the robustness of the camera calibration in spite of undesired variations of the camera parameters or the processing time that it takes to retrieve ocean wave measurements from the stereo videos, which are very large datasets that need to be processed efficiently to be of practical usage. Multiresolution and short-time approaches would improve efficiency and scalability of the techniques so that wave displacements are obtained in feasible times.

Space-time Reconstruction of Oceanic Sea States via Variational Stereo Methods

We present a remote sensing observational method for the measurement of the spatio-temporal dynamics of ocean waves. Variational techniques are used to recover a coherent space-time reconstruction of oceanic sea states given stereo video imagery. The stereoscopic reconstruction problem is expressed in a variational optimization framework. There, we design an energy functional whose minimizer is the desired temporal sequence of wave heights. The functional combines photometric observations as well as spatial and temporal regularizers. A nested iterative scheme is devised to numerically solve, via 3-D multigrid methods, the system of partial differential equations resulting from the optimality condition of the energy functional. The output of our method is the coherent, simultaneous estimation of the wave surface height and radiance at multiple snapshots. We demonstrate our algorithm on real data collected off-shore. Statistical and spectral analysis are performed. Comparison with respect to an existing sequential method is analyzed.

On the monitoring of surface displacement in connection with volcano reactivation in Tenerife, Canary Islands, using space techniques

Geodetic volcano monitoring in Tenerife has mainly focused on the Las Cañadas Caldera, where a geodetic micronetwork and a levelling profile are located. A sensitivity test of this geodetic network showed that it should be extended to cover the whole island for volcano monitoring purposes. Furthermore, InSAR allowed detecting two unexpected movements that were beyond the scope of the traditional geodetic network. These two facts prompted us to design and observe a GPS network covering the whole of Tenerife that was monitored in August 2000. The results obtained were accurate to one centimetre, and confirm one of the deformations, although they were not definitive enough to confirm the second one. Furthermore, new cases of possible subsidence have been detected in areas where InSAR could not be used to measure deformation due to low coherence. A first modelling attempt has been made using a very simple model and its results seem to indicate that the deformation observed and the groundwater level variation in the island may be related. Future observations will be necessary for further validation and to study the time evolution of the displacements, carry out interpretation work using different types of data (gravity, gases, etc) and develop models that represent the island more closely. The results obtained are important because they might affect the geodetic volcano monitoring on the island, which will only be really useful if it is capable of distinguishing between displacements that might be linked to volcanic activity and those produced by other causes. One important result in this work is that a new geodetic monitoring system based on two complementary techniques, InSAR and GPS, has been set up on Tenerife island. This the first time that the whole surface of any of the volcanic Canary Islands has been covered with a single network for this purpose. This research has displayed the need for further similar studies in the Canary Islands, at least on the islands which pose a greater risk of volcanic reactivation, such as Lanzarote and La Palma, where InSAR techniques have been used already.

Kinematic analysis of a novel 2-d.o.f. orientation device

This paper presents the development of a new parallel robot designed for helping with bone milling surgeries. The robot is a small modular wrist with 2 active degrees of freedom, and it is proposed to be used as an orientation device located at the end of a robotic arm designed for bone milling processes. A generic kinematic geometry is proposed for this device. This first article shows the developments on the workspace optimization and the analysis of the force field required to complete a reconstruction of the inferior jawbone. The singularities of the mechanism are analyzed, and the actuator selection is justified with the torque requirements and the study of the force space. The results obtained by the simulations allow building a first prototype using linear motors. Bone milling experiment video is shown as additional material.

Plasma kinetics issues in an ESA study for a plasma laboratory in space

A study supported by the European Space Agency (ESA), in the context of its General Studies Programme, performed an investigation of the possible use of space for studies in pure and applied plasma physics, in areas not traditionally covered by ‘space plasma physics’. A set of experiments have been identified that can potentially provide access to new phenomena and to allow advances in several fields of plasma science. These experiments concern phenomena on a spatial scale (101–104 m) intermediate between what is achievable on the ground and the usual solar system plasma observations. Detailed feasibility studies have been performed for three experiments: active magnetic experiments, largescale discharges and long tether–plasma interactions. The perspectives opened by these experiments are discussed for magnetic reconnection, instabilities, MHD turbulence, atomic excited states kinetics, weakly ionized plasmas,plasma diagnostics, artificial auroras and atmospheric studies. The discussion is also supported by results of numerical simulations and estimates.

Time and space partitioning the EagleEye reference mission

We discuss experiences gained by porting a Software Validation Facility (SVF) and a satellite Central Software (CSW) to a platform with support for Time and Space Partitioning (TSP). The SVF and CSW are part of the EagleEye Reference mission of the European Space Agency (ESA). As a reference mission, EagleEye is a perfect candidate to evaluate practical aspects of developing satellite CSW for and on TSP platforms. The specific TSP platform we used consists of a simulate D LEON3 CPU controlled by the XtratuM separation micro-kernel. On top of this, we run five separate partitions. Each partition ru n s its own real-time operating system or Ada run-time kernel, which in turn are running the application software of the CSW. We describe issues related to partitioning; inter-partition communication; scheduling; I/O; and fault-detection, isolation, and recovery (FDIR)

The ESA "Plasma Laboratory in Space" study

The European Space Agency has initiated, in the context of its General Studies Programme, a study of the possible use of space for studies in pure and applied plasma physics, in areas not traditionally covered by “space plasma physics”. A team of experts has been set-up to review a broad range of area including industrial plasma physics and pure plasma physics, astrophysical and solar-terrestrial areas. A set of experiments have been identified that can potentially provide access to new phenomena and to allow advances in several fields of plasma science. These experiments concern phenomena on spatial scale (102 to104 m) intermediate between what is achievable on ground experiment and usual solar system plasma observations.

Propellantless de orbiting of space debris by bare electrodynamic tethers

A 3-year Project started on November 1 2010, financed by the European Commision within the FP-7 Space Program, and aimed at developing an efficient de-orbit system that could be carried on board by future spacecraft launched into LEO, will be presented. The operational system will deploy a thin uninsulated tape-tether to collect electrons as a giant Langmuir probe, using no propellant/no power supply, and generating power on board. This project will involve free-fall tests, and laboratory hypervelocity-impact and tether-current tests, and design/Manufacturing of subsystems: interface elements, electric control and driving module, electron-ejecting plasma contactor, tether-deployment mechanism/end-mass, and tape samples. Preliminary results to be presented involve: i) devising criteria for sizing the three disparate tape dimensions, affecting mass, resistance, current-collection, magnetic self-field, and survivability against debris itself; ii) assessing the dynamical relevance of tether parameters in implementing control laws to limit oscillations in /off the orbital plane, where passive stability may be marginal; iii) deriving a law for bare-tape current from numerical simulations and chamber tests, taking into account ambient magnetic field, ion ram motion, and adiabatic electron trapping; iv) determining requirements on a year-dormant hollow cathode under long times/broad emission-range operation, and trading-off against use of electron thermal emission; v) determining requirements on magnetic components and power semiconductors for a control module that faces high voltage/power operation under mass/volume limitations; vi) assessing strategies to passively deploy a wide conductive tape that needs no retrieval, while avoiding jamming and ending at minimum libration; vii) evaluating the tape structure as regards conductive and dielectric materials, both lengthwise and in its cross-section, in particular to prevent arcing in triple-point junctions.

BETs: Propellant less de orbiting of space debris by bare electrodynamic tethers

As a fundamental contribution to limiting the increase of debris in the Space environment, a three-year project started on 1 November 2010 financed by the European Commission under the FP-7 Space Programme. It aims at developing a universal system to be carried on board future satellites launched into low Earth orbit (LEO), to allow de-orbiting at end of life. The operational system involves a conductive tape-tether left bare of insulation to establish anodic contact with the ambient plasma as a giant Langmuir probe. The project will size the three disparate dimensions of a tape for a selected de-orbit mission and determine scaling laws to allow system design for a general mission. It will implement control laws to restrain tether dynamics in/off the orbital plane; and will carry out plasma chamber measurements and numerical simulations of tether-plasma interaction. The project also involves the design and manufacturing of subsystems: electron-ejecting plasma contactors, an electric control and power module, interface elements, tether and deployment mechanisms, tether tape/end-mass as well as current collection plus free-fall, and hypervelocity impact tests.

Joint 4-D variational stereo reconstruction and camera calibration refinement for oceanic sea state measurements

Validating modern oceanographic theories using models produced through stereo computer vision principles has recently emerged. Space-time (4-D) models of the ocean surface may be generated by stacking a series of 3-D reconstructions independently generated for each time instant or, in a more robust manner, by simultaneously processing several snapshots coherently in a true ?4-D reconstruction.? However, the accuracy of these computer-vision-generated models is subject to the estimations of camera parameters, which may be corrupted under the influence of natural factors such as wind and vibrations. Therefore, removing the unpredictable errors of the camera parameters is necessary for an accurate reconstruction. In this paper, we propose a novel algorithm that can jointly perform a 4-D reconstruction as well as correct the camera parameter errors introduced by external factors. The technique is founded upon variational optimization methods to benefit from their numerous advantages: continuity of the estimated surface in space and time, robustness, and accuracy. The performance of the proposed algorithm is tested using synthetic data produced through computer graphics techniques, based on which the errors of the camera parameters arising from natural factors can be simulated.

J.A.D.E. jardín y arquitectura doméstica del este: (la casa contemporánea japonesa, el refugio y el jardín, Tokio: 1991-2011)

El capítulo 1 de esta tesis doctoral describe conceptos relativos a la ontología y a la arquitectura como, por ejemplo, la cuestión de “El lugar” o “Basho” o el espacio visto desde un punto de vista filosófico. En este capítulo se examinan las diferencias y similitudes entre la ideología oriental y la filosofía de occidente a lo largo de la historia y se esbozan los puntos comunes entre ambas en cuestiones que atañen al habitar. En el capítulo 2, estos conceptos se enumeran y ordenan y se extraen diferentes conclusiones en cuanto a la percepción de valores como el espacio o el vacío, fundamentales para entender la arquitectura y el paisaje en las culturas de Oriente y Occidente. El capítulo 3 describe el paisaje oriental y el jardín chino a modo de prólogo del de Japón. Este capítulo introduce al lector en la historia del jardín y explica las transformaciones que éste ha sufrido a lo largo de la historia de China. El capítulo 4 es una asimilación de los conceptos examinados en los capítulos 1,2 y 3 y en él se analizan los aspectos compositivos fundamentales del jardín chino y sus elementos como, por ejemplo, el centro, el límite, el agua o la montaña. El capítulo 5 consiste en una introducción al paisaje japonés que comienza con el estudio de su geografía, su lengua, su literatura y sus períodos históricos más importantes previos a la era moderna: la era primitiva “Jomon”, la era “Yayoi”, los tres Shogunatos y la Revolución Meiji. La segunda parte del capítulo 5 describe los jardines japoneses a lo largo de la historia tales como el jardín Karesansui, los jardines de Kioto o el arte del jardín Tatebana, entre otros. El capítulo 6 comienza con una copia del texto medieval japonés, “HOJOKI”. Al igual que en los capítulos 2 y 4, en el capítulo 6 se extraen los valores del capítulo anterior, esta vez, mediante un comentario de texto. En esencia, este libro demuestra la importancia de la “cabaña en la naturaleza” para la cultura japonesa, así como la relación del espacio doméstico y el jardín a lo largo de su historia. El capítulo 7 describe la evolución del paisaje de la ciudad china en paralelo a la evolución del paisaje urbano japonés que se desarrolla en el capítulo 9. El capítulo 8 es un nexo de unión entre los capítulos 7 y 9 puesto que explica las influencias paisajísticas y urbanas mutuas entre las culturas china y japonesa a lo largo de la historia como es el caso del trazado de las antiguas ciudades capitales chinas y japonesas o el de los paisajes y urbes proyectados sobre la topografía de Manchuria durante la ocupación japonesa de China. El capítulo 9 describe el paisaje japonés moderno, sus ciudades y sus paisajes interurbanos como, por ejemplo, el Tokai-do. A continuación describe la evolución de la arquitectura y el jardín japonés a lo largo del siglo XX, los principales movimientos de vanguardia, las circunstancias económicas que llevaron al país a la crisis de los 90 y la lenta recuperación económica posterior. Por último, este capítulo explica la destrucción del paisaje del norte tras El Gran Terremoto del Este del 2011 y su recuperación a corto plazo. El capítulo 10 se compone de tres entrevistas a tres figuras relevantes del mundo académico y de la arquitectura japonesa. Algunos de los temas que exponen son la arquitectura doméstica japonesa, el jardín y la naturaleza de esta cultura, la situación de la ciudad de Tokio o el rol del arquitecto en la sociedad contemporánea, entre otros. Además de estas cuestiones, se debate acerca de los recursos y la recuperación del país tras El Gran Terremoto del Este de Japón. Finalmente, el capítulo 11 consiste en un estudio en profundidad acerca del paisaje de la ciudad de Tokio y el espacio doméstico y el jardín en base a los conceptos estudiados en los capítulos 1 y 2 y en relación a los valores paisajísticos vistos en los capítulos 3,4,5 y 6, además de los temas urbanos y topográficos estudiados en los capítulos 7,8,9 y 10. En este capítulo se estudia la figura del sujeto individual y colectivo, el refugio, el jardín, las acciones urbanas del Machizukuri, el parque y la morfología y evolución de los barrios centrales de Tokio y sus espacios domésticos y parques y jardines vistos a través de los datos estadísticos proporcionados por el gobierno. Además, el texto estudia un total de 21 casos seleccionados y analizados a través de la comparación de cerca de 800 viviendas domésticas publicadas entre 1991 y 2011 en las revistas de gran prestigio nacional e internacional, Shinkenchiku Jutakutokushu y GA Houses. Tras el análisis de los casos de estudio, se extraen una serie de conclusiones y clasificaciones del jardín en el espacio doméstico del centro de Tokio en dicho periodo. Los últimos tres capítulos de la tesis doctoral se dividen en: una traducción al inglés del resumen y las conclusiones más importantes del capítulo 11 (capítulo 12) una conclusión y resumen homólogos en japonés (capítulo 13) y un cuaderno de dibujos a mano realizado por la autora sobre especies botánicas naturalizadas domésticas de la ciudad de Tokio (capítulo 14) ABSTRACT Chapter 1 of this Ph.D. thesis describes concepts related to ontology and architecture like the issue of “The place” in Japan, or “The space” as seen from a philosophic point of view. In this chapter, the differences between the essential ancient Asian ideology and the philosophical contemporary thought of the East are discussed, and at the same time the transcendental thought coming from the West is analysed and compared to both of them. In Chapter 2 these concepts are analysed specifically in the field of “inhabiting the domestic space” and the text fathoms the common points between Eastern and Western thought relating to the house and the garden. Chapter 3 describes the oriental landscape and garden of China as a prologue to that of Japan. This chapter starts with a brief description of the history of the garden in the East and the West and introduces the reader into the geography and changes that have taken place in China since the birth of its culture. Chapter 4 entails a brief assimilation of what has been deduced from chapters 1, 2 and 3. In this chapter the compositive and design aspects of the Chinese garden are described, aspects such as centre, limit, the element of the mountain, emptiness, water, and vision or the theatre. Chapter 5 is an introduction to the history of landscape and architecture in Japan that starts with a geographical insight into the country and with a short summary about the language, the primitive “Jomon” culture, the “Yayoi” era , the three Shogunates.and the Meiji Revolution. In the second part of chapter 5, the text describes Japanese gardens throughout history, for example the Karesansui garden, the history of Kyoto and its gardens, the garden in relationship with art and with Japanese literature or the art of Tatebana. Chapter 6 starts with a copy of the medieval text “HOJOKI” and discusses issues such as the meaning of “the hut in the nature” for Japanese culture and its relationship with the domestic space and the garden. Chapter 7 discusses the development of cities in the landscape in Chinese culture in parallel with an observation of the evolution of cities in Japanese culture and landscape. Chapter 8 is the crux of the Ph.D. research as it explains the mutual influences of landscape, urban planning, construction and architecture between Japan in China. Chapter 9 describes the Japanese urban planning since the very first urban developments and develops a study on the evolution of the Japanese cities and roads (like the Tokai-do) in the landscape. Also, it describes the reconstruction of the cities of Japan after the Second World War, the cultural vanguard movements, the economical circumstances that led to the Japan´ s economic crisis of the 90´s and the slow recovery of its economy. Also, at the end of this chapter, the text analyses the event of the Great East Japan Earthquake of 211. Chapter 10 of this Ph.D. research is composed of a number of interviews with architects and professors about architecture, nature in the domestic space, the role of the architect nowadays in addition to facts about energy and about the Great East Japan Earthquake . Finally, chapter 11 consists of a deep study concerning the current situation in the city of Tokyo and the relationship between its domestic spaces (dwellings) and gardens based on the philosophical values studied in chapters 1 and 2, aswell as the landscape values of the garden studied in chapters 3,4,5, and 6 plus the information about the cities in the landscape studied in chapters 7,8, 9 and 10. In this chapter the main goal is to study the human being, the refuge, the garden, the urban planning actions of Machizukuri, the park and the morphology and evolution of the central quarters of Tokyo and of its domestic spaces and parks seen through the statistical data provided by the Japanese government in the last decades. Also, the text provides a study on 21 cases selected and analysed through the comparison of around 800 domestic spaces designed in between 1991 and 2011 and published in “Shinkenchiku Jutakutokushu” and “GA Houses” magazines. After these study cases, a number of conclusions are developed and also a classification of the domestic garden in the center of Tokyo. The last three chapters of this Ph.D. work are divided in: the translation to English of the summary and main conclusions of chapter 11 of the research in Chapter 12, the translation to Japanese of the summary and main conclusions of chapter 11 of the research in Chapter 13, and a collection of hand-drawings done by the author about the botanical species found in the gardens of the domestic realms of Tokyo in Chapter 14.