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- Anamorfoses e perspectivas curvilíneasPublication . Araújo, AntónioUm texto relativo à construção de perspectivas cilíndricas e esféricas.
- 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.
- 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.
- Workshop - Drawing equirectangular perspectives for VR panoramas with Eq A Sketch 360Publication . Araújo, AntónioIn this workshop we will explore the construction of immersive environments in equirectangular perspective using the Eq A Sketch 360 software. Eq A Sketch 360 is a serious toy for spherical perspective drawing. It has two innovative features: a sliding geodesic grid and an equirectangular snap-to ruler. These tools turn equirectangular drawing into a proper perspective, where all lines and vanishing points may be drawn by hand, to create immersive environments from either observation or imagination. This contrasts with previous methods of equirectangular drawing, that either avoided perspective altogether by drawing directly in VR view, or were limited to fixed grid methods with ad-hoc estimation of measurements. Eq A Sketch both forces and helps the user to learn spherical perspective. We will show how to draw by hand with perfect control of proportions and bearings, to make standalone designs or constructions that can be mixed with 360-degree photography.
- Anamorphosis reformed: from optical illusions to immersive perspectivesPublication . Araújo, AntónioWe discuss a definition of conical anamorphosis that sets it at the foundation of both classical and curvilinear perspectives. In this view, anamorphosis is an equivalence relation between three-dimensional objects, which includes two-dimensional representatives, not necessarily flat. Vanishing points are defined in a canonical way that is maximally symmetric, with exactly two vanishing points for every line. The definition of the vanishing set works at the level of anamorphosis, before perspective is defined, with no need for a projection surface. Finally, perspective is defined as a flat representation of the visual data in the anamorphosis. This schema applies to both linear and curvilinear perspectives and is naturally adapted to immersive perspectives, such as the spherical perspectives. Mathematically, the view here presented is that the sphere and not the projective plane is the natural manifold of visual data up to anamorphic equivalence. We consider how this notion of anamorphosis may help to dispel some long-standing philosophical misconceptions regarding the nature of perspective.
- Let's Sketch in 360º: spherical perspectives for virtual reality panoramasPublication . Araújo, AntónioIn this workshop we will learn how to draw a 360-degree view of our environment using spherical perspective, and how to visualize these drawings as immersive panoramas by uploading them to virtual reality platforms that provide an interactive visualization of a 3D reconstruction of the original scene. We shall show how to construct these drawing in a simple way, using ruler and compass constructions, facilitated by adequate gridding that takes advantage of the symmetry groups of these spherical perspectives. We will consider two spherical perspectives: equirectangular and azimuthal equidistant, with a focus on the former due to its seamless integration with visualization software readily available on social networks. We will stress the relationship between these panoramas and the notion of spherical anamorphosis.
- Anamorphosis: optical games with perspective's playful parentPublication . Araújo, AntónioWe 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.
- Cardboarding mixed reality with Dürer MachinesPublication . Araújo, AntónioMixed 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.
- A GeoGebra tool for drawing immersive perspectivesPublication . Araújo, AntónioSpherical perspective provides a connection between traditional handmade drawings and virtual reality environments, which can be exploited to create new forms of hybrid immersive artworks. We discuss the use of GeoGebra tools as auxiliary software for the creation of immersive designs in azimuthal equidistant (360-degree fisheye) spherical perspective.