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- Anamorfoses e perspectivas curvilíneasPublication . Araújo, AntónioUm texto relativo à construção de perspectivas cilíndricas e esféricas.
- Topologia, anamorfose, e o bestiário das perspectivas curvilíneasPublication . Araújo, AntónioFaz-se uma breve digressão pelo catálogo das perspectivas curvilíneas centrais, descrevendo algumas das suas propriedades topológicas, geométricas, e ópticas, enfatizando a sua ligação com o conceito fundamental de anamorfose com vista a esclarecer alguns equívocos clássicos relativos à posição fundamental ocupada pela perspectiva clássica.
- Ruler, compass, and nail: constructing a total spherical perspectivePublication . Araújo, AntónioWe obtain a construction of a total spherical perspective with ruler, compass, and nail. This is a generalization of the spherical perspective of Barre and Flocon to a 360-degree field of view. Since the 1960s, several generalizations of this perspective have been proposed, but they were either works of a computational nature, inadequate for drawing with simple instruments, or lacked a general method for solving all vanishing points. We establish a general setup for anamorphosis and central perspective, define the total spherical perspective within this framework, study its topology, and show how to solve it with simple instruments. We consider its uses both in freehand drawing and in computer visualization, and its relation with the problem of reflection on a sphere.
- Anamorfoses e outras tecnologias imersivas no contexto da educação artísticaPublication . Flores, Manuel; Araújo, António; Figueiredo, MauroApresentamos uma proposta de investigação na área da média-arte digital onde se pretende combinar os princípios da anamorfose com as novas tecnologias baseadas na realidade aumentada. Esta perspetiva tem subjacente a ideia de que é possível relacionar a anamorfose cónica com as projeções realizadas em Realidade Aumentada. No âmbito desta investigação propõe-se uma abordagem ao estudo da perspetiva centrada nos contributos de Dürer e nos conceitos fundamentais da construção de anamorfoses. Pretende-se refletir sobre as possibilidades desta abordagem metodológica e analisar os seus contributos no desenvolvimento da capacidade de visualização espacial dos alunos do 3º ciclo do ensino básico e, desta forma, facilitar a compreensão dos conceitos relativos ao ensino da geometria.
- HIMmaterial: exploring new hybrid media for immersive drawing and collagePublication . Araújo, António; Olivero, Lucas; Antinozzi, SaraWe propose an installation that explores Hybrid Immersive Models (HIM), the conjunction of digital VR panoramas with physical, handmade spherical perspectives and anamorphoses, as a new hybrid art medium that connects traditional drawing with digital, immersive art, creating a dialogue between material and immaterial forms of visual expression.
- Guidelines for drawing immersive panoramas in equirectangular perspectivePublication . Araújo, AntónioVirtual Reality (VR) Panoramas work by interactively creating immersive anamorphoses from spherical perspectives. These panoramas are usually photographic but a growing number of artists are making hand-drawn equirectangular perspectives in order to visualize them as VR panoramas. This is a practice with both artistic and didactic interest. However, these drawings are usually done by trial-and-error, with ad-hoc measurements and interpolation of precomputed grids, a process with considerable limitations.We develop in this work the analytic tools for plotting great circles, straight line images and their vanishing points, and then provide guidelines for achieving these constructions in good approximation without computer calculations, through descriptive geometry diagrams that can be executed using only ruler, compass, and protractor.
- Insights about an interactive film installationPublication . Silva, Bruno; Tavares, Mirian; António, Rui; Costa, Susana; Monteiro, Paula; Araújo, AntónioThe question of time and its relation to cinema is the common thread in this paper. Through research based on experimental practice, this paper explores, firstly, the psychosomatic processes that may give the viewer different perceptions of time. Secondly, it describes the working process of a film that intends to provide the viewer with the possibility of intervening in the film narrative in a disruptive way, seeking the possibility of subverting the filmic discourse.
- Limits of tangents of quasi-ordinary hypersurfacesPublication . Araújo, António; Neto, OrlandoWe compute explicitly the limits of tangents of a quasi-ordinary singularity in terms of its special monomials. We show that the set of limits of tangents of Y is essentially a topological invariant of Y .
- On the use of quasi-equidistant source points over the sphere surface for the method of fundamental solutionsPublication . Araújo, António; Serranho, PedroThe method of fundamental solutions is broadly used in science and engineering to numerically solve the direct time-harmonic scattering problem. In 2D the choice of source points is usually made by considering an inner pseudo-boundary over which equidistant source points are placed. In 3D, however, this problem is much more challenging, since, in general, equidistant points over a closed surface do not exist. In this paper we discuss a method to obtain a quasi-equidistant point distribution over the unit sphere surface, giving rise to a Delaunay triangulation that might also be used for other boundary element methods. We give theoretical estimates for the expected distance between points and the expect area of each triangle. We illustrate the feasibility of the proposed method in terms of the comparison with the expected values for distance and area. We also provide numerical evidence that this point distribution leads to a good conditioning of the linear system associated with the direct scattering problem, being therefore an adequated choice of source points for the method of fundamental solutions.
- Boxing the visual sphere: towards a systematic solution of the cubical perspectivePublication . Araújo, António; Olivero, Lucas; Rossi, AdrianaCubic perspective is an attractive option for drawing VR panoramas, as it carries with it the familiarity of classical perspective and its ease of drawing line segments. Its simplicity is however only apparent as the transition of line images between the various planes of the cube can be baffling to the draughtsman. We argue that the best way to systematize this perspective is to see it fully as a spherical perspective and start by classifying and rendering its geodesics.