Simulação da profundidade de campo

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Informática

XCSurf: Riprogettazione dell'Interfaccia Utente

Il Progetto XCModel, che da dieci anni si sviluppa e si perfeziona col contributo di varie persone, consente la progettazione di scene 3D e la resa fotorealistica. Esso si appoggia sulle funzionalita' grafiche di X-Window in Linux: si tratta di un ambiente in costante evoluzione, dovuta sia alle continue innovazioni hardware che ai cambiamenti degli standard. XCModel e' composto da vari pacchetti, ognuno dei quali specializzato nel trattare un particolare aspetto della modellazione o della resa (curve, superfici, textures, luci, ...) e che si presentano come applicazioni dotate di una sofisticata interfaccia grafica. Tutte attingono alle funzioni della Libreria XTools, che fornisce numerose primitive grafiche facenti uso delle potenzialita' di X-Window. I recenti cambiamenti nelle specifiche di X-Org, ed in particolare la de- standardizzazione del backing-store, ha obbligato il team di XCModel ad una consistente riprogettazione di XTools e di tutti i pacchetti che su di esso s'appoggiano. S'e' colta l'occasione per un massiccio debugging e per modificare i pacchetti in base alle impressioni emerse nel corso degli anni da parte degli utilizzatori, primi tra tutti gli studenti del corso di Grafica tenuto dal Prof. Giulio Casciola, project-manager di XCModel: questa e' un'ulteriore testimonianza del continuo adattamento e dell'aggiornabilita' del Progetto! Nella fattispecie, ci si occupera' delle modifiche effettuate in particolare al pacchetto XCSurf, finalizzato alla creazione ed alla modifica di curve e superfici 3D da utilizzarsi successivamente per la creazione delle scene: tale pacchetto e' di fatto risultato il pie' avulso dalle specifiche di XTools, il che ha costretto ad un massiccio intervento al codice del programma, ma d'altro canto ha consentito una standardizzazione del pacchetto in linea con gli altri, in particolare ridisegnandone l'interfaccia. Nel primo capitolo si effettuera' una veloce panoramica dell'ambiente XCModel e delle problematiche emerse dai cambiamenti degli standard di X-Window. Il secondo capitolo affrontera' un'ampia analisi dell'hardware, del software e dei paradigmi che caratterizzano la grafica interattiva, e gli ambienti necessari per interagire con essa ed esaminando i vari obiettivi raggiungibili. Infine, il terzo capitolo analizzera' nel dettaglio le modifiche effettuate ai pacchetti di XCModel ed in particolare ad XCSurf per l'adattamento ai nuovi standard, nel rispetto delle politiche e delle linee guida dettate dalla grafica interattiva.

Analysis and treatment of a nineteenth century portrait, study of Artsorb® and a proposal for a microclimate frame

The present work is divided in two parts: Part 1 is focused on the analysis and treatment of a 19th century portrait of Domingos Affonso, which belongs to the Ecomuseu Municipal do Seixal; and Part 2, which is entitled “The Microclimate Frame Project” is focused on the study of Artsorb® and on the planning of a microclimate frame for the painting. In Part 1, a study of the painting’s materials was performed using complementary analytical techniques and the painting’s condition was carefully evaluated. The painting exhibited signs of mould growth, and a more detailed investigation was made of this topic to understand if the fungal community was active and if it represented a real danger to the painting. A treatment was proposed, appropriate to the painting’s condition. A description of the treatment carried out, comprising the treatment options, is also present in this section. Within the study of the microclimate frame, in Part 2, the study of the potential corrosiveness of Artsorb® was a central subject. Artsorb® sheets are one of the most widely used materials for buffering relative humidity fluctuations in microclimate frames and its reported excellent performance is enhanced by its availability in lightweight sheets that can be easily placed inside microclimate frames. However, concerns have arisen regarding the presence of the corrosive salt lithium chloride in the composition of this buffer. Consequently, the present work also aimed to understand the potential risks of using Artsorb® and the possibility of avoiding exposure of lithium chloride to the artworks through the use of Tyvek®. Results from the preliminary tests seem to indicate that Artsorb® releases lithium chloride into air. This study also showed that a Tyvek® cover over Artsorb® reduces but does not eliminate evidence of chlorine contamination, and it significantly reduces the effectiveness of the buffering material. Considering that Artsorb® appears to be unsuitable due to the release of the corrosive salt, that Tyvek® was not efficient as a barrier for lithium chloride or as a permeable material to enable the proper functioning of Artsorb®, the buffering material proposed for the use in the microclimate frames is silica gel without indicator. Based on the choice of buffering material, as a result of this study, a microclimate frame is proposed.

A Homogeneous Set-Theoretical Frame for Clustering Fuzzy Relational Data

Our purpose is to provide a set-theoretical frame to clustering fuzzy relational data basically based on cardinality of the fuzzy subsets that represent objects and their complementaries, without applying any crisp property. From this perspective we define a family of fuzzy similarity indexes which includes a set of fuzzy indexes introduced by Tolias et al, and we analyze under which conditions it is defined a fuzzy proximity relation. Following an original idea due to S. Miyamoto we evaluate the similarity between objects and features by means the same mathematical procedure. Joining these concepts and methods we establish an algorithm to clustering fuzzy relational data. Finally, we present an example to make clear all the process

A Homogeneous Set-Theoretical Frame for Clustering Fuzzy Relational Data

Our purpose is to provide a set-theoretical frame to clustering fuzzy relational data basically based on cardinality of the fuzzy subsets that represent objects and their complementaries, without applying any crisp property. From this perspective we define a family of fuzzy similarity indexes which includes a set of fuzzy indexes introduced by Tolias et al, and we analyze under which conditions it is defined a fuzzy proximity relation. Following an original idea due to S. Miyamoto we evaluate the similarity between objects and features by means the same mathematical procedure. Joining these concepts and methods we establish an algorithm to clustering fuzzy relational data. Finally, we present an example to make clear all the process

Coding of visual space during motor preparation: approaching objects rapidly modulate corticospinal excitability in hand-centered coordinates

Defensive behaviors, such as withdrawing your hand to avoid potentially harmful approaching objects, rely on rapid sensorimotor transformations between visual and motor coordinates. We examined the reference frame for coding visual information about objects approaching the hand during motor preparation. Subjects performed a simple visuomanual task while a task-irrelevant distractor ball rapidly approached a location either near to or far from their hand. After the distractor ball appearance, single pulses of transcranial magnetic stimulation were delivered over the subject's primary motor cortex, eliciting motor evoked potentials (MEPs) in their responding hand. MEP amplitude was reduced when the ball approached near the responding hand, both when the hand was on the left and the right of the midline. Strikingly, this suppression occurred very early, at 70-80ms after ball appearance, and was not modified by visual fixation location. Furthermore, it was selective for approaching balls, since static visual distractors did not modulate MEP amplitude. Together with additional behavioral measurements, we provide converging evidence for automatic hand-centered coding of visual space in the human brain.

Deleterious effect of TRIS buffer on growth rates and pigment content of Gracilaria birdiae Plastino & EC Oliveira (Gracilariales, Rhodophyta)

This work evaluated the effects of Tris (hydroxymethyl)-aminomethane (TRIS) buffer and its interaction with nutrient concentration on the development of Gracilaria birdie, a common species on the Brazilian coast that has been exploited for agar production. Responses to different conditions were assessed through growth rates and pigment content (chlorophyll a, phycoerythrin, phycocyanin and allophycocyanin). Provasoli`s nutrient solution with and without TRIS addition was tested at concentrations of 12.5, 25 and 50%. The pH was also monitored. G. birdiae grew better in the absence of TRIS and at low nutrient concentrations, 12.5 and 25% (growth rates of 10.8-11.3%.day(-1)). Higher contents of phycoerythrin and chlorophyll a were observed without TRIS at 12.5 and 25% (Phycoerythrin, 649.6-698.0 mu g g(-1) fresh biomass; Chlorophyll a, 156.0-168.6 mu g g(-1) fresh biomass). These findings highlight the deleterious effect of TRIS on growth and phycoerythrin and chlorophyll a content. They also demonstrate the importance of appropriate nutrient concentration for laboratory cultures, depending on the intrinsic characteristics of each species.

IFTrace: Video segmentation of deformable objects using the Image Foresting Transform

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tracking of industrial objects by using CAD models

In this paper we present a model-based approach for real-time camera pose estimation in industrial scenarios. The line model which is used for tracking is generated by rendering a polygonal model and extracting contours out of the rendered scene. By un-projecting a point on the contour with the depth value stored in the z-buffer, the 3D coordinates of the contour can be calculated. For establishing 2D/3D correspondences the 3D control points on the contour are projected into the image and a perpendicular search for gradient maxima for every point on the contour is performed. Multiple hypotheses of 2D image points corresponding to a 3D control point make the pose estimation robust against ambiguous edges in the image.

Tight frames of k-plane ridgelets and the problem of representing objects that are smooth away from d-dimensional singularities in Rn

For each pair (n, k) with 1 ≤ k < n, we construct a tight frame (ρλ : λ ∈ Λ) for L2 (Rn), which we call a frame of k-plane ridgelets. The intent is to efficiently represent functions that are smooth away from singularities along k-planes in Rn. We also develop tools to help decide whether k-plane ridgelets provide the desired efficient representation. We first construct a wavelet-like tight frame on the X-ray bundle χn,k—the fiber bundle having the Grassman manifold Gn,k of k-planes in Rn for base space, and for fibers the orthocomplements of those planes. This wavelet-like tight frame is the pushout to χn,k, via the smooth local coordinates of Gn,k, of an orthonormal basis of tensor Meyer wavelets on Euclidean space Rk(n−k) × Rn−k. We then use the X-ray isometry [Solmon, D. C. (1976) J. Math. Anal. Appl. 56, 61–83] to map this tight frame isometrically to a tight frame for L2(Rn)—the k-plane ridgelets. This construction makes analysis of a function f ∈ L2(Rn) by k-plane ridgelets identical to the analysis of the k-plane X-ray transform of f by an appropriate wavelet-like system for χn,k. As wavelets are typically effective at representing point singularities, it may be expected that these new systems will be effective at representing objects whose k-plane X-ray transform has a point singularity. Objects with discontinuities across hyperplanes are of this form, for k = n − 1.

Accounting information systems as knowledge objects:some effects of objectualization

This paper will outline a research methodology informed by theorists who have contributed to actor network theory (ANT). Research informed from such a perspective recognizes the constitutive role of accounting systems in the achievement of broader social goals. Latour, Knoor Cetina and others argue that the bringing in of non-human actants, through the growth of technology and science, has added immeasurably to the complexity of modern society. The paper ‘sees’ accounting and accounting systems as being constituted by technological ‘black boxes’ and seeks to discuss two questions. One concerns the processes which surround the establishment of ‘facts’, i.e. how ‘black boxes’ are created or accepted (even if temporarily) within society. The second concerns the role of existing ‘black boxes’ within society and organizations. Accounting systems not only promote a particular view of the activities of an organization or a subunit, but in their very implementation and operation ‘mobilize’ other organizational members in a particular direction. The implications of such an interpretation are explored in this paper. Firstly through a discussion of some of the theoretic constructs that have been proposed to frame ANT research. Secondly an attempt is made to relate some of these ideas to aspects of the empirics in a qualitative case study. The case site is in the health sector and involves the implementation of a casemix accounting system. Evidence from the case research is used to exemplify aspects of the theoretical constructs.

Exploring the effect of buffer behaviour on perceived video quality

In this work we deal with video streams over TCP networks and propose an alternative measurement to the widely used and accepted peak signal to noise ratio (PSNR) due to the limitations of this metric in the presence of temporal errors. A test-bed was created to simulate buffer under-run in scalable video streams and the pauses produced as a result of the buffer under-run were inserted into the video before being employed as the subject of subjective testing. The pause intensity metric proposed in [1] was compared with the subjective results and it was shown that in spite of reductions in frame rate and resolution, a correlation with pause intensity still exists. Due to these conclusions, the metric may be employed in layer selection in scalable video streams. © 2011 IEEE.

ViDRILO: The Visual and Depth Robot Indoor Localization with Objects information dataset

In this article we describe a semantic localization dataset for indoor environments named ViDRILO. The dataset provides five sequences of frames acquired with a mobile robot in two similar office buildings under different lighting conditions. Each frame consists of a point cloud representation of the scene and a perspective image. The frames in the dataset are annotated with the semantic category of the scene, but also with the presence or absence of a list of predefined objects appearing in the scene. In addition to the frames and annotations, the dataset is distributed with a set of tools for its use in both place classification and object recognition tasks. The large number of labeled frames in conjunction with the annotation scheme make this dataset different from existing ones. The ViDRILO dataset is released for use as a benchmark for different problems such as multimodal place classification and object recognition, 3D reconstruction or point cloud data compression.

The Atomic Structure Of A Bare Buffer Layer On Sic(0001) Chemically Resolved.

A chemical-specific photoelectron diffraction structure determination of a carbon rich buffer layer on SiC is reported. In addition to the long-range ripple of this surface, a local buckling in the hexagonal sublattice, which breaks the local range order symmetry, was unraveled.

Deleterious effect of TRIS buffer on growth rates and pigment content of Gracilaria birdiae Plastino & E.C. Oliveira (Gracilariales, Rhodophyta)

This work evaluated the effects of Tris (hydroxymethyl)-aminomethane (TRIS) buffer and its interaction with nutrient concentration on the development of Gracilaria birdie, a common species on the Brazilian coast that has been exploited for agar production. Responses to different conditions were assessed through growth rates and pigment content (chlorophyll a, phycoerythrin, phycocyanin and allophycocyanin). Provasoli's nutrient solution with and without TRIS addition was tested at concentrations of 12.5, 25 and 50%. The pH was also monitored. G. birdiae grew better in the absence of TRIS and at low nutrient concentrations, 12.5 and 25% (growth rates of 10.8-11.3%.day-1). Higher contents of phycoerythrin and chlorophyll a were observed without TRIS at 12.5 and 25% (Phycoerythrin, 649.6-698.0 μg g-1 fresh biomass; Chlorophyll a, 156.0-168.6 μg g-1 fresh biomass). These findings highlight the deleterious effect of TRIS on growth and phycoerythrin and chlorophyll a content. They also demonstrate the importance of appropriate nutrient concentration for laboratory cultures, depending on the intrinsic characteristics of each species.