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In the context of Computer-Aided Design and Manufacturing, the problem of feature recognition plays a key role in the integration of systems. Until now, compromises have been reached by only using FACE-based geometric information of prismatic CAD models to prune the search domain. This manuscripts presents a feature recognition method which more aggressively prunes the search space with reconfigurable geometric tests. This reconfigurable approach allows to enforce arbitrary confluent tests which are topologic and geometric, with enlarged domain. The test sequence is itself a graph (i.e. not a linear or total-order sequence). Unlike the existing methods which are FACE-based, the present one permits combinations of topologies whose dimensions are 2, 1 or 0. This system has been implemented in an industrial environment. The industrial incarnation allows industry-based customization and is faster when compared to topology-based feature recognition. Future work is required in improving robustness of search conditions and improving the graphic input interface., Spanish Computer Graphics Conference (CEIG), Short Papers, 69, 72, Juan Camilo Pareja Corcho, Oscar Mauricio Betancur Acosta, Oscar E. Ruiz, and Carlos Cadavid, CCS Concepts: Applied computing--> Computer-aided design; Computer-aided manufacturing

Visualization of vector fields plays an important role in research activities nowadays. Web applications allow a fast, multi-platform and multi-device access to data, which results in the need of optimized applications to be implemented in both high and low-performance devices. The computation of trajectories usually repeats calculations due to the fact that several points might lie over the same trajectory. This paper presents a new methodology to calculate point trajectories over a highly-dense and uniformly-distributed grid of points in which the trajectories are forced to lie over the points in the grid. Its advantages rely on a highly parallel computing implementation and in the reduction of the computational effort to calculate the stream paths since unnecessary calculations are avoided by reusing data through iterations. As case study, the visualization of oceanic streams in the web platform is presented and analyzed, using WebGL as the parallel computing architecture and the rendering engine.

In the context of computer numerical control (CNC) and computer aided manufacturing (CAM), the capabilities of programming languages such as symbolic and intuitive programming, program portability and geometrical portfolio have special importance. They allow to save time and to avoid errors during part programming and permit code re-usage. Our updated literature review indicates that the current state of art presents voids in parametric programming, program portability and programming flexibility. In response to this situation, this article presents a compiler implementation for EGCL (Extended G-code Language), a new, enriched CNC programming language which allows the use of descriptive variable names, geometrical functions and flow-control statements (if-then-else, while). Our compiler produces low-level generic, elementary ISO-compliant Gcode, thus allowing for flexibility in the choice of the executing CNC machine and in portability. Our results show that readable variable names and flow control statements allow a simplified and intuitive part programming and permit re-usage of the programs. Future work includes allowing the programmer to define own functions in terms of EGCL, in contrast to the current status of having them as library built-in functions., {"references":["Alfred V. Aho, Monica S. Lam, Ravi Sethi, and Jeffrey D. Ullman.\nCompilers: Principles, Techniques, and Tools (2nd Edition). Addison\nWesley, 2006.","G. Arroyo, C. Ochoa, J. Silva, and G. Vidal. Towards CNC Programming\nUsing Haskell. Advances in Artificial Intelligence-IBERAMIA 2004,\npages 386-396, 2004.","X. Guo, Y. Liu, D. Du, K. Yamazaki, and M. Fujishima. A Universal\nNC Program Processor Design and Prototype Implementation for\nCNC Systems. The International Journal of Advanced Manufacturing\nTechnology, pages 1-15, 2011.","S Habeeb and X Xu. A Novel CNC System for Turning Operations\nBased on a High-Level Data Model. The International Journal of\nAdvanced Manufacturing Technology, 43:323-336, 2009.","International Organization for Standardization (1982). ISO 6983-1: Numerical\ncontrol of machines - Program format and definition of address\nwords - Part 1: Data format for positioning, line motion and contouring\ncontrol systems. International Organization for Standardization, Geneva,\nSwitzerland.","International Organization for Standardization (2004). ISO 14649-\n1: Industrial automation systems and integration - Data model for\ncomputerized numerical controllers - Part 1: overview and fundamental\nprinciples. International Organization for Standardization, Geneva,\nSwitzerland.","SC. Johnson. YACC - Yet Another Compiler-Compiler. Computer\nScience, Technical Report 32, 1975.","ME Lesk. Lex - A Lexical Analyzer Generator. Computing Science,\nTechnical Report 39, 1975.","Y. Liu, X. Guo, W. Li, K. Yamazaki, K. Kashihara, and M. Fujishima.\nAn Intelligent NC Program Processor for CNC System of Machine\nTool. Robotics and Computer-Integrated Manufacturing, 23(2):160-169,\n2007.\n[10] S. Nagle and J. Wiegley. GSP: Extending G-Code Using JSP Servlet\nTechnologies. In Automation Science and Engineering, 2008. CASE\n2008. IEEE International Conference on, pages 953-958. IEEE, 2008.\n[11] D.T. Ross. The Design and Use of the APT Language for Automatic\nProgramming of Numerically Controlled Machine Tools. In Proc. 1959\nComputer Applications Symposium, Chiergo, pages 80-99, 1959.\n[12] T. Schroeder and M. Hoffmann. Flexible Automatic Converting of NC\nPrograms. A Cross-compiler for Structured Text. International Journal\nof Production Research, 44(13):2671-2679, 2006.\n[13] S.J. Shin, S.H. Suh, and I. Stroud. Reincarnation of G-code Based Part\nPrograms Into STEP-NC for Turning Applications. Computer-Aided\nDesign, 39(1):1-16, 2007.\n[14] Bulldog Digital Technologies. Free CNC-Simulator (Version 4.53f)\n(Software). Avaliable from http://www.cncsimulator.com, 2007.\n[15] J. Zhang, L. Wang, S. Li, and F. Zhang. The Research of an Intelligent\nOpen CNC System. Initiatives of Precision Engineering at the Beginning\nof a Millennium, pages 779-783, 2002."]}

Gabriel-constrained Parametric Surface Triangulation

The Boundary Representation of a 3D manifold contains FACES (connected subsets of a parametric surface S : R2 -! R3). In many science and engineering applications it is cumbersome and algebraically difficult to deal with the polynomial set and constraints (LOOPs) representing the FACE. Because of this reason, a Piecewise Linear (PL) approximation of the FACE is needed, which is usually represented in terms of triangles (i.e. 2-simplices). Solving the problem of FACE triangulation requires producing quality triangles which are: (i) independent of the arguments of S, (ii) sensitive to the local curvatures, and (iii) compliant with the boundaries of the FACE and (iv) topologically compatible with the triangles of the neighboring FACEs. In the existing literature there are no guarantees for the point (iii). This article contributes to the topic of triangulations conforming to the boundaries of the FACE by applying the concept of parameterindependent Gabriel complex, which improves the correctness of the triangulation regarding aspects (iii) and (iv). In addition, the article applies the geometric concept of tangent ball to a surface at a point to address points (i) and (ii). Additional research is needed in algorithms that (i) take advantage of the concepts presented in the heuristic algorithm proposed and (ii) can be proved correct., {"references":["K. Abe, J. Bisceglio, T. J. Peters, A. C. Russell, and T. Sakkalis.\nComputational topology for reconstruction of surfaces with boundary:\nIntegrating experiments and theory. In SMI -05: Proceedings of the\nInternational Conference on Shape Modeling and Applications 2005,\npages 290-299, Washington, DC, USA, 2005. IEEE Computer Society.","Udo Adamy, Joachim Giesen, and Matthias John. New techniques for\ntopologically correct surface reconstruction. In VIS -00: Proceedings of\nthe conference on Visualization -00, pages 373-380, Los Alamitos, CA,\nUSA, 2000. IEEE Computer Society Press.","N. Amenta, M. Bern, and D. Eppstein. The crust and the betaskeleton:\nCombinatorial curve reconstruction. Graphical models and\nimage processing: GMIP, 60(2):125-, 1998.","Nina Amenta and Marshall Bern. Surface reconstruction by voronoi\nfiltering. In SCG -98: Proceedings of the fourteenth annual symposium\non Computational geometry, pages 39-48, New York, NY, USA, 1998.\nACM.","Dominique Attali, Jean-Daniel Boissonnat, and Andr'e Lieutier. Complexity\nof the delaunay triangulation of points on surfaces the smooth\ncase. In SCG -03: Proceedings of the nineteenth annual symposium on\nComputational geometry, pages 201-210, New York, NY, USA, 2003.\nACM.","J-D Boissonnat and S. Oudot. An effective condition for sampling\nsurfaces with guarantees. In SM -04: Proceedings of the ninth ACM\nsymposium on Solid modeling and applications, pages 101-112, Airela-\nVille, Switzerland, Switzerland, 2004. Eurographics Association.","Jean-Daniel Boissonnat and Steve Oudot. Provably good sampling and\nmeshing of lipschitz surfaces. In SCG -06: Proceedings of the twentysecond\nannual symposium on Computational geometry, pages 337-346,\nNew York, NY, USA, 2006. ACM.","Manfredo Do Carmo. Differential geometry of curves and surfaces,\npages 1-168. Prentice Hall, 1976. ISBN: 0-13-212589-7.","Siu-Wing Cheng, Tamal K. Dey, Edgar A. Ramos, and Tathagata\nRay. Sampling and meshing a surface with guaranteed topology and\ngeometry. In SCG -04: Proceedings of the twentieth annual symposium\non Computational geometry, pages 280-289, New York, NY, USA, 2004.\nACM.\n[10] L. Paul Chew. Guaranteed-quality mesh generation for curved surfaces.\nIn SCG -93: Proceedings of the ninth annual symposium on Computational\ngeometry, pages 274-280, New York, NY, USA, 1993. ACM.\n[11] Museo del Oro Bogot'a DC. Pre-columbian fish.\nhttp://www.banrep.org/museo/eng/home4.htm.\n[12] Herbert Edelsbrunner and Nimish R. Shah. Triangulating topological\nspaces. In SCG -94: Proceedings of the tenth annual symposium on\nComputational geometry, pages 285-292, New York, NY, USA, 1994.\nACM.\n[13] Rosalinda Ferrandes. Pump carter.\nhttp://shapes.aimatshape.net/viewgroup.php?id=919.\n[14] Rosalinda Ferrandes. Stub axle.\nhttp://shapes.aimatshape.net/viewgroup.php?id=917.\n[15] Greg Leibon and David Letscher. Delaunay triangulations and voronoi\ndiagrams for riemannian manifolds. In SCG -00: Proceedings of the\nsixteenth annual symposium on Computational geometry, pages 341-\n349, New York, NY, USA, 2000. ACM.\n[16] A' ngel Montesdeoca. Apuntes de geometr'ıa diferencial de curvas y\nsuperficies. Santa Cruz de Tenerife, 1996. ISBN: 84-8309-026-0.\n[17] Oscar E. Ruiz, John Congote, Carlos Cadavid, Juan G. Lalinde, and\nGuillermo Peris. Parameter-independent, curvature-sensitive sprinkle\nand star algorithms for surface triangulation. Submitted to the Computer-\nAided Design Journal at Elsevier editorial.\n[18] Oscar E. Ruiz and Sebastian Pe˜na. Aspect ratio- and size-controlled\npatterned triangulations of parametric surfaces. In Ninth IASTED Intl.\nConf. Computer Graphics and Imaging, February 13-15 2007."]}

Geometric characteristics of 2-manifolds embedded in R3 space have been analyzed from the point of view of differential geometry and topology. In the past, results relevant to these areas have been found for C-curves and surfaces. However, current scientific, industrial, entertainment and medical applications, and availability of more powerful point sampling systems, press for characterization of discrete counterparts for the continuous properties and characteristics evaluated previously in C-curves and surfaces. Recent works have presented estimation methods for properties such as the principal and rotatect quadrics of point sampled surfaces. The present article user the findings of previous investigations to propose and implement a method for evaluation of planarity of surfaces. It is based on: (i) Estimation of partial mesh fitting sets of planar or grid sample points. (ii) Evaluation of the piecewise - linear (PL) version of families of geodesic curves on the mesh. (iii) Diagnostic of the property of planarity based on the behavior of the families of geodesic curves. The present work can be applied in the area of design and manufacturing of products based on sheet materials, such as apparel, metal stamping, thin structures, etc.