Problems when generating virtual models representing real objects: Hondarribia walls

[EN] This paper is based in the following project:

Dynamic picture of the inner asteroid belt: implications for the density, size and taxonomic distributions of real objects

In this paper, we construct a dynamic portrait of the inner asteroidal belt. We use information about the distribution of test particles, which were initially placed on a perfectly rectangular grid of initial conditions, after 4.2 Myr of gravitational interactions with the Sun and five planets, from Mars to Neptune. Using the spectral analysis method introduced by Michtchenko et al., the asteroidal behaviour is illustrated in detail on the dynamical, averaged and frequency maps. On the averaged and frequency maps, we superpose information on the proper elements and proper frequencies of real objects, extracted from the data base, AstDyS, constructed by Milani and Knezevic. A comparison of the maps with the distribution of real objects allows us to detect possible dynamical mechanisms acting in the domain under study; these mechanisms are related to mean-motion and secular resonances. We note that the two- and three-body mean-motion resonances and the secular resonances (strong linear and weaker non-linear) have an important role in the diffusive transportation of the objects. Their long-lasting action, overlaid with the Yarkovsky effect, may explain many observed features of the density, size and taxonomic distributions of the asteroids.

Utilizing Real Objects to Increase Reading Comprehension in Students with Significant Cognitive Disabilities

This poster presents the results of a study conducted to evaluate the effects of pairing read-alouds with real objects related to stories read to students with significant cognitive disabilities to increase reading comprehension skills. The participants are four elementary students. The target audience is special education teachers.

Incidental Memory of Younger and Older Adults for Objects Encountered in a Real World Context

Effects of context on the perception of, and incidental memory for, real-world objects have predominantly been investigated in younger individuals, under conditions involving a single static viewpoint. We examined the effects of prior object context and object familiarity on both older and younger adults' incidental memory for real objects encountered while they traversed a conference room. Recognition memory for context-typical and context-atypical objects was compared with a third group of unfamiliar objects that were not readily named and that had no strongly associated context. Both older and younger adults demonstrated a typicality effect, showing significantly lower 2-alternative-forced-choice recognition of context-typical than context-atypical objects; for these objects, the recognition of older adults either significantly exceeded, or numerically surpassed, that of younger adults. Testing-awareness elevated recognition but did not interact with age or with object type. Older adults showed significantly higher recognition for context-atypical objects than for unfamiliar objects that had no prior strongly associated context. The observation of a typicality effect in both age groups is consistent with preserved semantic schemata processing in aging. The incidental recognition advantage of older over younger adults for the context-typical and context-atypical objects may reflect aging-related differences in goal-related processing, with older adults under comparatively more novel circumstances being more likely to direct their attention to the external environment, or age-related differences in top-down effortful distraction regulation, with older individuals' attention more readily captured by salient objects in the environment. Older adults' reduced recognition of unfamiliar objects compared to context-atypical objects may reflect possible age differences in contextually driven expectancy violations. The latter finding underscores the theoretical and methodological value of including a third type of objects-that are comparatively neutral with respect to their contextual associations-to help differentiate between contextual integration effects (for schema-consistent objects) and expectancy violations (for schema-inconsistent objects).

Investigating shape-from-shading illusions using solid objects

Recent growth in the shape-from-shading psychophysics literature has been paralled by an increasing availability of computer graphics hardware and software, to the extent that most psychophysical studies in this area now employ computer lighting algorithms. The most widely used of algorithms is shape-from-shading psychophysics is the Phong lighting model. This model, and other shading models of its genre, produce readily ineterpretable imiages of three-dimensional scenes. However, such algorithms are only approximations of how light interacts with real objects in the natural environment. Nevertheless, the results from psychophysical experiments using these techniques have been used to infer the processes underlying the perception of shape-from-shading in natural environments. It is important to establish whether this substitution is ever valid. We report a series of experiments investigating whether two recently reported illusions seen computer-generated, Phond shaded images occur for solid objects under real illuminants. The two illusions investigated are three-dimensional curvature contrast and the illuminant-position effect on perceived curvature. We show that both effects do occur for solid objects, and that the magnitude of these effects are equivalent regardless of whether subjects are presented with ray traced or solid objects.

Unimanual and Bimanual Weight Perception of Virtual Objects with a new Multi-finger Haptic Interface

Accurate weight perception is important particularly in tasks where the user has to apply vertical forces to ensure safe landing of a fragile object or precise penetration of a surface with a probe. Moreover, depending on physical properties of objects such as weight and size we may switch between unimanual and bimanual manipulation during a task. Research has shown that bimanual manipulation of real objects results in a misperception of their weight: they tend to feel lighter than similarly heavy objects which are handled with one hand only [8]. Effective simulation of bimanual manipulation with desktop haptic interfaces should be able to replicate this effect of bimanual manipulation on weight perception. Here, we present the MasterFinger-2, a new multi-finger haptic interface allowing bimanual manipulation of virtual objects with precision grip and we conduct weight discrimination experiments to evaluate its capacity to simulate unimanual and bimanual weight. We found that the bimanual ‘lighter’ bias is also observed with the MasterFinger-2 but the sensitivity to changes of virtual weights deteriorated.

Learning environments – Laboratories at the cross roads

Laboratories and technical hands on learning have always been a part of Engineering and Science based university courses. They provide the interface where theory meets practice and students may develop professional skills through interacting with real objects in an environment that models appropriate standards and systems. Laboratories in many countries are facing challenges to their sustainable operation and effectiveness. In some countries such as Australia, significantly reduced funding and staff reduction is eroding a once strong base of technical infrastructure. Other countries such as Thailand are seeking to develop their laboratory infrastructure and are in need of staff skill development, management and staff structure in technical areas. In this paper the authors will address the need for technical development with reference to work undertaken in Thailand and Australia. The authors identify the roads which their respective university sectors are on and point out problems and opportunities. It is hoped that the cross roads where we meet will result in better directions for both.

The Empty City (production)

This creative work is the production of the live and animated performance of The Empty City. With a significant period of creative development and script work behind it, the team engaged in a range of innovative performance-making practices in order to realise the work onstage as a non-verbal live and animated theatre work. This intermedial process was often led by music, and involved the creation and convergence of non-verbal action, virtual performers, performing objects and two simultaneous projections of animated images. The production opened at the Brisbane Powerhouse on June 27 2013, with a subsequent tour to Perth’s Awesome Festival in October 2013. Its technical achievements were noted in the critical responses. "The story is told on a striking set of two huge screens, the front one transparent, upon which still and moving images are projected, and between which Oliver performs and occasional “real” objects are placed. The effect is startling, and creates a cartoon three dimensionality like those old Viewmaster slide shows. The live action… and soundscape sync perfectly with the projected imagery to complete a dense, intricately devised and technically brilliant whole." (The West Australian 14.10.13)

[G_Hondarribia_Muralla] Documentación geométrica de las murallas de Hondarribia

[ES] Al respecto del modelo virtual con texturas fotográficas generado en este proyecto, se puede consultar también el siguiente artículo:

Obtaining the shape of a moving object with a specular surface

This paper addresses the basic problem of recovering the 3D surface of an object that is observed in motion by a single camera and under a static but unknown lighting condition. We propose a method to establish pixelwise correspondence between input images by way of depth search by investigating optimal subsets of intensities rather than employing all the relevant pixel values. The thrust of our algorithm is that it is capable of dealing with specularities which appear on the top of shading variance that is caused due to object motion. This is in terms of both stages of finding sparse point correspondence and dense depth search. We also propose that a linearised image basis can be directly computed by the procudure of finding the correspondence. We illustrate the performance of the theoretical propositions using images of real objects. © 2009. The copyright of this document resides with its authors.

An Application of Augmented Reality (AR) in the Teaching of an Arc Welding Robot

Augmented Reality (AR) is an emerging technology that utilizes computer vision methods to overlay virtual objects onto the real world scene so as to make them appear to co-exist with the real objects. Its main objective is to enhance the user’s interaction with the real world by providing the right information needed to perform a certain task. Applications of this technology in manufacturing include maintenance, assembly and telerobotics. In this paper, we explore the potential of teaching a robot to perform an arc welding task in an AR environment. We present the motivation, features of a system using the popular ARToolkit package, and a discussion on the issues and implications of our research.

3D surface point and wireframe reconstruction from multiview photographic images

This paper describes a new method for reconstructing 3D surface points and a wireframe on the surface of a freeform object using a small number, e.g. 10, of 2D photographic images. The images are taken at different viewing directions by a perspective camera with full prior knowledge of the camera configurations. The reconstructed surface points are frontier points and the wireframe is a network of contour generators. Both of them are reconstructed by pairing apparent contours in the 2D images. Unlike previous works, we empirically demonstrate that if the viewing directions are uniformly distributed around the object's viewing sphere, then the reconstructed 3D points automatically cluster closely on a highly curved part of the surface and are widely spread on smooth or flat parts. The advantage of this property is that the reconstructed points along a surface or a contour generator are not under-sampled or under-represented because surfaces or contours should be sampled or represented with more densely points where their curvatures are high. The more complex the contour's shape, the greater is the number of points required, but the greater the number of points is automatically generated by the proposed method. Given that the viewing directions are uniformly distributed, the number and distribution of the reconstructed points depend on the shape or the curvature of the surface regardless of the size of the surface or the size of the object. The unique pattern of the reconstructed points and contours may be used in 31) object recognition and measurement without computationally intensive full surface reconstruction. The results are obtained from both computer-generated and real objects. (C) 2007 Elsevier B.V. All rights reserved.

Selecting object pairs for action: is the active object always first?

Perception is linked to action via two routes: a direct route based on affordance information in the environment and an indirect route based on semantic knowledge about objects. The present study explored the factors modulating the recruitment of the two routes, in particular which factors affecting the selection of paired objects. In Experiment 1, we presented real objects among semantically related or unrelated distracters. Participants had to select two objects that can interact. The presence of distracters affected selection times, but not the semantic relations of the objects with the distracters. Furthermore, participants first selected the active object (e.g. teaspoon) with their right hand, followed by the passive object (e.g. mug), often with their left hand. In Experiment 2, we presented pictures of the same objects with no hand grip, congruent or incongruent hand grip. Participants had to decide whether the two objects can interact. Action decisions were faster when the presentation of the active object preceded the presentation of the passive object, and when the grip was congruent. Interestingly, participants were slower when the objects were semantically but not functionally related; this effect increased with congruently gripped objects. Our data showed that action decisions in the presence of strong affordance cues (real objects, pictures of congruently gripped objects) relied on sensory-motor representation, supporting the direct route from perception-to-action that bypasses semantic knowledge. However, in the case of weak affordance cues (pictures), semantic information interfered with action decisions, indicating that semantic knowledge impacts action decisions. The data support the dual-route account from perception-to-action.

Monismo do corpo: único ponto de partida atualmente possível para o desenvolvimento de uma psicologia científica

Inicia-se o trabalho, reconstituindo-se, sob um ponto de vista histórico, o problema do dualismo e do monismo, na Psicologia. A reconstituição é feita partindo-se de uma origem situada em Sócrates e, dai, desenvolvendo-se até os dias atuais, onde, demonstra-se, a questão permanece. A identificação daquela origem foi determinada pela circunstância de, alí, o problema ter merecido um estudo sistematizado e ter se caracterizado como metafísico. Entendendo-se, com isso, que a questão a resolver era a respeito do que existiria como entidade autônoma. Neste caso, então, se apenas o "corpo", se apenas a "mente" ou se os dois. As soluções que propunham a existência só da mente (monistas da mente), ou de mente e corpo, enquanto entidades distintas (dualistas) viriam a ser, portanto, decisivas para a própria concepção da Psicologia. Como se afirma ser, a partir de uma decisão referente ao problema anterior, que se deva desenvolver uma Psicologia cientifica, estabelece-se, no capítulo II, as concepções adotadas para Ciência, conhecimento científico e método científico. Ali, aproveita-se para justificar porque parte do estudo deve cair sob o domínio da Filosofia da Ciência, como um todo e da Filosofia da Psicologia, em particular. No capítulo III, volta-se a demonstrar com maior ênfase, que o problema "mente-corpo" é, ainda hoje, metafísico e requer uma tomada de decisão, naqueles termos. Mostra-se que a decisão é sempre tomada quando nada como pressuposto, senão explícito, pelo menos implícito. Uma vez tendo-se demonstrado que só o corpo pode ser afirmado como representando alguma coisa que exista, em termos reais, no sentido metafísico, parte-se para o estabelecimento daquele que seria o autêntico objeto de estudo da Psicologia. Fazendo-se, então, uso de uma Semântica Filosófica "crítico-realista", demonstra-se que ele termina sendo: o conjunto de propriedades do objeto real representado pelo corpo e responsáveis pelas manifestações pelas quais a Psicologia, por uma tradição de investigação, sempre se interessou. Finalmente, no capítulo IV, concebe-se um modelo sistêmico para representar a Natureza. Nele vige a 'lei' da transformação, que resulta da' interação entre os subsistemas. Entre os subsistemas existem aqueles que representam objetos reais e são designados como "Corpo Humano". Estes estão sujeitos à mesma 'lei'. A partir da transformação do U23592 em Pb20782, constrói-se duas funções matemáticas, com base na teoria dos conjuntos, para demonstrar-se como funciona a lei da transformação ou a função transformação, aplicável a todos os subsistemas, que são elementos do Sistema que representa a Natureza. Dessas construções e mais algumas, ao serem aplicadas aos subsistemas que representam os objetos reais denotados como Corpo Humano, extrai-se um grande número de consequências para a Psicologia. Termina-se apresentando um modelo específico para representar o objeto real denotado por Corpo Humano. Este, como subsistema, também é um sistema e composto de quatro subsistemas: Motor, Emocional, Perceptivo e Cognitivo. O todo e as partes passam a funcionar regidos pela lei da Transformação.