Portuguese Meeting on Computer Graphics 2003
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Browsing Portuguese Meeting on Computer Graphics 2003 by Author "Jorge, Joaquim"
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Item BlobMaker: Free-Form Modelling with Variational Implicit Surfaces(The Eurographics Association, 2021) Araújo, Bruno; Jorge, Joaquim; Marcos, Adérito and Mendonça, Ana and Leitão, Miguel and Costa, António and Jorge, JoaquimWe present BlobMaker, a program for modelling surfaces using variational implicit surfaces. Our approach uses variational implicit surfaces as a geometrical representation for free-form shapes. We have implemented new modelling operations to support stroke (pen-based) input. To this end, we have built a complete modeller application using variational implicit surfaces. Users can create and manipulate shapes using sketches on a perspective or parallel view. The main operations are inflate, which creates 3D forms from a 2D stroke, merge, which creates a 3D shape from two blobs and oversketch, which allows users to redefine shapes using a single stroke to change their boundaries or to modify a surface by an implicit extrusion. We compare these techniques with those of other approaches published. Finally, we describe their implementation in BlobMaker. We have provided additional features such as copying, picking and dragging to offer a natural user interface suitable free-form modelling.Item GIDes ++(The Eurographics Association, 2021) Jorge, Joaquim; Silva, Nelson; Cardos, Tiago; Marcos, Adérito and Mendonça, Ana and Leitão, Miguel and Costa, António and Jorge, JoaquimGIDes ++ is a gesture based calligraphic 3D modeller using expectation lists, and extends the notion of natural and efficient interface. A brand new look and a new modeller kernel empower the modelling capabilities. A measures layer enables the user to visualize and change measures, giving a new dimension in precise and accurate modelling. Adding new modalities like handwriting and speech, GIDes ++ present a natural and intelligent multimodal interface enabling quick models prototyping creation. Visually, much effort is being made to create a more appealing and elegant application, but keeping always in mind the usefulness of these visual effects.Item Polygon Detection from a Set of Lines(The Eurographics Association, 2021) Jr., Alfredo Ferreira; Fonseca, Manuel; Jorge, Joaquim; Marcos, Adérito and Mendonça, Ana and Leitão, Miguel and Costa, António and Jorge, JoaquimDetecting polygons defined by a set of line segments in a plane is an important step in the analysis of vectorial drawings. This paper presents an approach that combines several algorithms to detect basic polygons from a set of arbitrary line segments. The resulting algorithm runs in polynomial time and space, with complexities of O((N + M)4) and O((N + M)2) respectively, where N is the number of line segments and M is the number of intersections between line segments. Our choice of algorithms was made to strike a good compromise between efficiency and ease of implementation. The result is a simple and efficient solution to detect polygons from lines.Item Task Analysis and Scenario-Based Design of Calligraphic Interfaces(The Eurographics Association, 2021) Dias, Filipe; Fonseca, Manuel; Jorge, Joaquim; Marcos, Adérito and Mendonça, Ana and Leitão, Miguel and Costa, António and Jorge, JoaquimThe great functionality of today's CAD systems enables the manufacturing of very complex models. Yet, great part of this power is unusable, early in the design process. As well, we have found two different approaches in two different car designers that surprisingly lead to the same long time in development. In this paper we identify the reasons for these problems, and propose a solution that bridges the different worlds of conceptual and geometric models, using the affordability of the calligraphic interface. Creating a prototype by drawing it allows impossible situations to be immediately identified and corrected, without further communication overheads, certifying that emotional drawing ideas correspond to the designer's intents.