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Topologia, anamorfose, e o bestiário das perspectivas curvilíneas

Publication . Araújo, António

Faz-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.

2016-09Journal article

Open access

Cardboarding mixed reality with Dürer Machines

Publication . Araújo, António

Mixed reality is a direct application of 15 to 17th century principles of anamorphosis. The inherent physicality of anamorphosis, materialized through the Dürer perspective machine makes it an excellent teaching tool for students of digital art interested in mixed reality, whose initial core competencies may be extremely varied. The needs of these students are not met by the mere ephemera of learning how to use a particular piece of software; such knowledge is both transient and limiting of imaginative possibilities. We discuss a didactic strategy of cardboarding, i.e., a process of deliberate rudimentarization, to expose the inner workings of opaque chains of digital processes, to both clarify the elements of these chains and create loci for artistic intervention at their points of connection.

2017Conference object

Open access

Anamorphosis: optical games with perspective's playful parent

Publication . Araújo, António

We explore conical anamorphosis in several variations and discuss its various constructions, both physical and diagrammatic. While exploring its playful aspect as a form of optical illusion, we argue against the prevalent perception of anamorphosis as a mere amusing derivative of perspective and defend the exact opposite view - that perspective is the derived concept, consisting of plane anamorphosis under arbitrary limitations and ad-hoc alterations. We show how to define vanishing points in the context of anamorphosis in a way that is valid for all anamorphs of the same set. We make brief observations regarding curvilinear perspectives, binocular anamorphoses, and color anamorphoses.

2017Conference object

Open access

Guidelines for drawing immersive panoramas in equirectangular perspective

Publication . Araújo, António

Virtual 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.

2017-09Conference object

Open access

η-conversions of IPC implemented in atomic F

Publication . Ferreira, Gilda

It is known that the β-conversions of the full intuitionistic propositional calculus (IPC) translate into βη-conversions of the atomic polymorphic calculus Fat. Since Fat enjoys the property of strong normalization for βη-conversions, an alternative proof of strong normalization for IPC considering β-conversions can be derived. In the present article, we improve the previous result by analysing the translation of the η-conversions of the latter calculus into a technical variant of the former system (the atomic polymorphic calculus Fat^∧_at). In fact, from the strong normalization of Fat^∧_at we can derive the strong normalization of the full intuitionistic propositional calculus considering all the standard (β and η) conversions.

2017Journal article

Open access