Reconstruction from image correspondences

A single picture provides a largely incomplete representation of the scene one is looking at. Usually it reproduces only a limited spatial portion of the scene according to the standpoint and the viewing angle, besides it contains only instantaneous information. Thus very little can be understood on the geometrical structure of the scene, the position and orientation of the observer with respect to it remaining also hard to guess. When multiple views, taken from different positions in space and time, observe the same scene, then a much deeper knowledge is potentially achievable. Understanding inter-views relations enables construction of a collective representation by fusing the information contained in every single image. Visual reconstruction methods confront with the formidable, and still unanswered, challenge of delivering a comprehensive representation of structure, motion and appearance of a scene from visual information. Multi-view visual reconstruction deals with the inference of relations among multiple views and the exploitation of revealed connections to attain the best possible representation. This thesis investigates novel methods and applications in the field of visual reconstruction from multiple views. Three main threads of research have been pursued: dense geometric reconstruction, camera pose reconstruction, sparse geometric reconstruction of deformable surfaces. Dense geometric reconstruction aims at delivering the appearance of a scene at every single point. The construction of a large panoramic image from a set of traditional pictures has been extensively studied in the context of image mosaicing techniques. An original algorithm for sequential registration suitable for real-time applications has been conceived. The integration of the algorithm into a visual surveillance system has lead to robust and efficient motion detection with Pan-Tilt-Zoom cameras. Moreover, an evaluation methodology for quantitatively assessing and comparing image mosaicing algorithms has been devised and made available to the community. Camera pose reconstruction deals with the recovery of the camera trajectory across an image sequence. A novel mosaic-based pose reconstruction algorithm has been conceived that exploit image-mosaics and traditional pose estimation algorithms to deliver more accurate estimates. An innovative markerless vision-based human-machine interface has also been proposed, so as to allow a user to interact with a gaming applications by moving a hand held consumer grade camera in unstructured environments. Finally, sparse geometric reconstruction refers to the computation of the coarse geometry of an object at few preset points. In this thesis, an innovative shape reconstruction algorithm for deformable objects has been designed. A cooperation with the Solar Impulse project allowed to deploy the algorithm in a very challenging real-world scenario, i.e. the accurate measurements of airplane wings deformations.

Rafael Moneo: la complessità del vuoto. Dalle matrici formali dell'opera di Oteiza e Chillida

The experience of void, essential to the production of forms and to make use them, can be considered as the base of the activities that attend to the formative processes. If void and matter constitutes the basic substances of architecture. Their role in the definition of form, the symbolic value and the constructive methods of it defines the quality of the space. This job inquires the character of space in the architecture of Moneo interpreting the meaning of the void in the Basque culture through the reading of the form matrices in the work of Jorge Oteiza and Eduardo Chillida. In the tie with the Basque culture a reading key is characterized by concurring to put in relation some of the theoretical principles expressed by Moneo on the relationship between place and time, in an unique and specific vision of the space. In the analysis of the process that determines the genesis of the architecture of Moneo emerges a trajectory whose direction is constructed on two pivos: on the one hand architecture like instrument of appropriation of the place, gushed from an acquaintance process who leans itself to the reading of the relations that define the place and of the resonances through which measuring it, on the other hand the architecture whose character is able to represent and to extend the time in which he is conceived, through the autonomy that is conferred to them from values. Following the trace characterized from this hypothesis, that is supported on the theories elaborated from Moneo, surveying deepens the reading of the principles that construct the sculptural work of Oteiza and Chillida, features from a search around the topic of the void and to its expression through the form. It is instrumental to the definition of a specific area that concurs to interpret the character of the space subtended to a vision of the place and the time, affine to the sensibility of Moneo and in some way not stranger to its cultural formation. The years of the academic formation, during which Moneo enters in contact with the Basque artistic culture, seem to be an important period in the birth of that knowledge that will leads him to the formulation of theories tied to the relationship between time, place and architecture. The values expressed through the experimental work of Oteiza and Chillida during years '50 are valid bases to the understanding of such relationships. In tracing a profile of the figures of Oteiza and Chillida, without the pretension that it is exhaustive for the reading of the complex historical period in which they are placed, but with the needs to put the work in a context, I want to be evidenced the important role carried out from the two artists from the Basque cultural area within which Moneo moves its first steps. The tie that approaches Moneo to the Basque culture following the personal trajectory of the formative experience interlaces to that one of important figures of the art and the Spanish architecture. One of the more meaningful relationships is born just during the years of his academic formation, from 1958 to the 1961, when he works like student in the professional office of the architect Francisco Sáenz de Oiza, who was teaching architectural design at the ETSAM. In these years many figures of Basque artists alternated at the professional office of Oiza that enjoys the important support of the manufacturer and maecenas Juan Huarte Beaumont, introduced to he from Oteiza. The tie between Huarte and Oteiza is solid and continuous in the years and it realizes in a contribution to many of the initiatives that makes of Oteiza a forwarder of the Basque culture. In the four years of collaboration with Oiza, Moneo has the opportunity to keep in contact with an atmosphere permeated by a constant search in the field of the plastic art and with figures directly connected to such atmosphere. It’s of a period of great intensity as in the production like in the promotion of the Basque art. The collective “Blanco y Negro”, than is held in 1959 at the Galería Darro to Madrid, is only one of the many times of an exhibition of the work of Oteiza and Chillida. The end of the Fifties is a period of international acknowledgment for Chillida that for Oteiza. The decade of the Fifties consecrates the hypotheses of a mythical past of the Basque people through the spread of the studies carried out in the antecedent years. The archaeological discoveries that join to a context already rich of signs of the prehistoric era, consolidate the knowledge of a strong cultural identity. Oteiza, like Chillida and other contemporary artists, believe in a cosmogonist conception belonging to the Basques, connected to their matriarchal mythological past. The void in its meaning of absence, in the Basque culture, thus as in various archaic and oriental religions, is equivalent to the spiritual fullness as essential condition to the revealing of essence. Retracing the archaic origins of the Basque culture emerges the deep meaning that the void assumes as key element in the religious interpretation of the passage from the life to the death. The symbology becomes rich of meaningful characters who derive from the fact that it is a chthonic cult. A representation of earth like place in which divine manifest itself but also like connection between divine and human, and this manipulation of the matter of which the earth it is composed is the tangible projection of the continuous search of the man towards God. The search of equilibrium between empty and full, that characterizes also the development of the form in architecture, in the Basque culture assumes therefore a peculiar value that returns like constant in great part of the plastic expressions, than in this context seem to be privileged regarding the other expressive forms. Oteiza and Chillida develop two original points of view in the representation of the void through the form. Both use of rigorous systems of rules sensitive to the physics principles and the characters of the matter. The last aim of the Oteiza’s construction is the void like limit of the knowledge, like border between known and unknown. It doesn’t means to reduce the sculptural object to an only allusive dimension because the void as physical and spiritual power is an active void, that possesses that value able to reveal the being through the trace of un-being. The void in its transcendental manifestation acts at the same time from universal and from particular, like in the atomic structure of the matter, in which on one side it constitutes the inner structure of every atom and on the other one it is necessary condition to the interaction between all the atoms. The void can be seen therefore as the action field that concurs the relations between the forms but is also the necessary condition to the same existence of the form. In the construction of Chillida the void represents that counterpart structuring the matter, inborn in it, the element in absence of which wouldn’t be variations neither distinctive characters to define the phenomenal variety of the world. The physics laws become the subject of the sculptural representation, the void are the instrument that concurs to catch up the equilibrium. Chillida dedicate himself to experience the space through the senses, to perceive of the qualities, to tell the physics laws which forge the matter in the form and the form arranges the places. From the artistic experience of the two sculptors they can be transposed, to the architectonic work of Moneo, those matrices on which they have constructed their original lyric expressions, where the void is absolute protagonist. An ambit is defined thus within which the matrices form them drafts from the work of Oteiza and Chillida can be traced in the definition of the process of birth and construction of the architecture of Moneo, but also in the relation that the architecture establishes with the place and in the time. The void becomes instrument to read the space constructed in its relationships that determine the proportions, rhythms, and relations. In this way the void concurs to interpret the architectonic space and to read the value of it, the quality of the spaces constructing it. This because it’s like an instrument of the composition, whose role is to maintain to the separation between the elements putting in evidence the field of relations. The void is that instrument that serves to characterize the elements that are with in the composition, related between each other, but distinguished. The meaning of the void therefore pushes the interpretation of the architectonic composition on the game of the relations between the elements that, independent and distinguished, strengthen themselves in their identity. On the one hand if void, as measurable reality, concurs all the dimensional changes quantifying the relationships between the parts, on the other hand its dialectic connotation concurs to search the equilibrium that regulated such variations. Equilibrium that therefore does not represent an obtained state applying criteria setting up from arbitrary rules but that depends from the intimate nature of the matter and its embodiment in the form. The production of a form, or a formal system that can be finalized to the construction of a building, is indissolubly tied to the technique that is based on the acquaintance of the formal vocation of the matter, and what it also can representing, meaning, expresses itself in characterizing the site. For Moneo, in fact, the space defined from the architecture is above all a site, because the essence of the site is based on the construction. When Moneo speaks about “birth of the idea of plan” like essential moment in the construction process of the architecture, it refers to a process whose complexity cannot be born other than from a deepened acquaintance of the site that leads to the comprehension of its specificity. Specificity arise from the infinite sum of relations, than for Moneo is the story of the oneness of a site, of its history, of the cultural identity and of the dimensional characters that that they are tied to it beyond that to the physical characteristics of the site. This vision is leaned to a solid made physical structure of perceptions, of distances, guideline and references that then make that the process is first of all acquaintance, appropriation. Appropriation that however does not happen for directed consequence because does not exist a relationship of cause and effect between place and architecture, thus as an univocal and exclusive way does not exist to arrive to a representation of an idea. An approach that, through the construction of the place where the architecture acquires its being, searches an expression of its sense of the truth. The proposal of a distinction for areas like space, matter, spirit and time, answering to the issues that scan the topics of the planning search of Moneo, concurs a more immediate reading of the systems subtended to the composition principles, through which is related the recurrent architectonic elements in its planning dictionary. From the dialectic between the opposites that is expressed in the duality of the form, through the definition of a complex element that can mediate between inside and outside as a real system of exchange, Moneo experiences the form development of the building deepening the relations that the volume establishes in the site. From time to time the invention of a system used to answer to the needs of the program and to resolve the dual character of the construction in an only gesture, involves a deep acquaintance of the professional practice. The technical aspect is the essential support to which the construction of the system is indissolubly tied. What therefore arouses interest is the search of the criteria and the way to construct that can reveal essential aspects of the being of the things. The constructive process demands, in fact, the acquaintance of the formative properties of the matter. Property from which the reflections gush on the relations that can be born around the architecture through the resonance produced from the forms. The void, in fact, through the form is in a position to constructing the site establishing a reciprocity relation. A reciprocity that is determined in the game between empty and full and of the forms between each other, regarding around, but also with regard to the subjective experience. The construction of a background used to amplify what is arranged on it and to clearly show the relations between the parts and at the same time able to tie itself with around opening the space of the vision, is a system that in the architecture of Moneo has one of its more effective applications in the use of the platform used like architectonic element. The spiritual force of this architectonic gesture is in the ability to define a place whose projecting intention is perceived and shared with who experience and has lived like some instrument to contact the cosmic forces, in a delicate process that lead to the equilibrium with them, but in completely physical way. The principles subtended to the construction of the form taken from the study of the void and the relations that it concurs, lead to express human values in the construction of the site. The validity of these principles however is tested from the time. The time is what Moneo considers as filter that every architecture is subordinate to and the survival of architecture, or any of its formal characters, reveals them the validity of the principles that have determined it. It manifests thus, in the tie between the spatial and spiritual dimension, between the material and the worldly dimension, the state of necessity that leads, in the construction of the architecture, to establish a contact with the forces of the universe and the intimate world, through a process that translate that necessity in elaboration of a formal system.

Synthesis of Hand Exoskeletons for the Rehabilitation of Post-Stroke Patients

This dissertation presents the synthesis of a hand exoskeleton (HE) for the rehabilitation of post-stroke patients. Through the analysis of state-of-the-art, a topological classification was proposed. Based on the proposed classification principles, the rehabilitation HEs were systematically analyzed and classified. This classification is helpful to both understand the reason of proposing certain solutions for specific applications and provide some useful guidelines for the design of a new HE, that was actually the primary motivation of this study. Further to this classification, a novel rehabilitation HE was designed to support patients in cylindrical shape grasping tasks with the aim of recovering the basic functions of manipulation. The proposed device comprises five planar mechanisms, one per finger, globally actuated by two electric motors. Indeed, the thumb flexion/extension movement is controlled by one actuator whereas a second actuator is devoted to the control of the flexion/extension of the other four fingers. By focusing on the single finger mechanism, intended as the basic model of the targeted HE, the feasibility study of three different 1 DOF mechanisms are analyzed: a 6-link mechanism, that is connected to the human finger only at its tip, an 8-link and a 12-link mechanisms where phalanges and articulations are part of the kinematic chain. The advantages and drawbacks of each mechanism are deeply analyzed with respect to targeted requirements: the 12-link mechanism was selected as the most suitable solution. The dimensional synthesis based on the Burmester theory as well as kinematic and static analyses were separately done for all fingers in order to satisfy the desired specifications. The HE was finally designed and a prototype was built. The experimental results of the first tests are promising and demonstrate the potential for clinical applications of the proposed device in robot-assisted training of the human hand for grasping functions.

The twofold role of Cloud Computing in Digital Forensics: target of investigations and helping hand to evidence analysis

This PhD thesis discusses the impact of Cloud Computing infrastructures on Digital Forensics in the twofold role of target of investigations and as a helping hand to investigators. The Cloud offers a cheap and almost limitless computing power and storage space for data which can be leveraged to commit either new or old crimes and host related traces. Conversely, the Cloud can help forensic examiners to find clues better and earlier than traditional analysis applications, thanks to its dramatically improved evidence processing capabilities. In both cases, a new arsenal of software tools needs to be made available. The development of this novel weaponry and its technical and legal implications from the point of view of repeatability of technical assessments is discussed throughout the following pages and constitutes the unprecedented contribution of this work