Portuguese Meeting on Computer Graphics 2002
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Browsing Portuguese Meeting on Computer Graphics 2002 by Author "Jorge, Joaquim A."
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Item Direct Modelíng: from Sketches to 3D Models(The Eurographics Association, 2022) Naya, Fernando; Jorge, Joaquim A.; Conesa, Julián; Contera, Manuel; Gomis, José Maria; Xavier Pueyo; Manuel Próspero dos Santos; Luiz Velholn spite of recent advances in Computer Aided Design, Graphical User Interfaces (GUJ) are, by and large, still at the stage of the so-called WIMP (Window, Icon, Menu, Pointing device) approach. ln recent years, our research team has developed different algorithms in Geometric Reconstruction. The aim of this effort is to obtain an automatic (or, at least, easy-to-use) means to generate 3D models from freehand 2D drawings. This approach serves as the basis to a calligraphic interface, based onfreehand sketches and gestures, described as a prototype application capable of modeling special kinds of objects such as normalon and quasi-normalon polyhedra. Using our system users can directly draw the axonometric view of an object to yield a 3D model. White much work remains to be done, the current application already shows gains with respect to more traditional forms ofmodeling in that it embodies a drawing approachfamiliar to most draflspeople, who can start modeling relatively complex shapes without much training. Preliminary studies show that our modeling system compares favorably to commercial grade CAD systems both in number of operations required to creating objects and time to accomplish simple modeling tasks.Item Towards Content-Based Retrieval of Technical Orawings through High-Oimensional lndexing(The Eurographics Association, 2022) Fonseca, Manuel J.; Jorge, Joaquim A.; Xavier Pueyo; Manuel Próspero dos Santos; Luiz VelhoThis paper presents a new approach to classify, index and retrieve technical drawings by content. Our work uses spatial relationships, visual elements and high-dimensional indexing mechanisms to retrieve complex drawings from CAD databases. This contrasts with conventional approaches which use mostly textual metadata for the sarne purpose. Creative designers and draftspeople often re-use data from previous projects, publications and libraries of ready to use components. Usually, retrieving these drawings is a slow, complex and error-prone endeavor; requiring either exhaustive visual examination, a solid memory, or both. Unfortunately, the widespread use of CAD systems, while making it easier to create and edit drawings, exacerbates this problem, insofar as the number of projects and drawings grows enormously, without providing adequate retrieval mechanisms to support retrieving these documents. ln this paper we describe an approach that supports automatic indexation of technical drawing databases through drawing simplification techniques based on geometric features and efficient algorithms to index large amounts of data. We describe in detail the indexing structure (NB-Tree) we have developed within the context of a more general approach. Experimental evaluation reveals that our approach outperforms some of the best indexing structures published, enabling us to search very large drawing databases.