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    Cylindrical Transform Slicing of Revolute Parts with Overhangs for Laser Metal Deposition
    (The Eurographics Association, 2022) Montoya-Zapata, Diego; Moreno, Aitor; Ortiz, Igor; Ruiz-Salguero, Oscar; Posada, Jorge; Posada, Jorge; Serrano, Ana
    In the context of Laser Metal Deposition (LMD), temporary support structures are needed to manufacture overhanging features. In order to limit the need for supports, multi-axis machines intervene in the deposition by sequentially repositioning the part. Under multi-axis rotations and translations, slicing and toolpath generation represent significant challenges. Slicing has been partially addressed by authors in multi-axis LMD. However, tool-path generation in multi-axis LMD is rarely touched. One of the reasons is that the required slices for LMD may be strongly non-developable. This fact produces a significant mismatch between the tool-path speeds and other parameters in Parametric space vs. actual Euclidean space. For the particular case of developable slices present in workpieces with cylindrical kernel and overhanging neighborhoods, this manuscript presents a methodology for LMD tool path generation. Our algorithm takes advantage of existing cylindrical iso-radial slicing by generating a path in the (?, z) parameter space and isometrically translating it into the R3 Euclidean space. The presented approach is advantageous because it allows the path-planning of complex structures by using the methods for conventional 2.5-axis AM. Our computer experiments show that the presented approach can be effectively used in manufacturing industrial/mechanical pieces (e.g., spur gears). Future work includes the generation of the machine g-code for actual LMD equipment.
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    Blast Features and Requirements for Fracturing Osseous Models
    (The Eurographics Association, 2018) Pérez, Francisco Daniel; Jiménez, Juan José; Jiménez, Juan Roberto; García-Fernández, Ignacio and Ureña, Carlos
    Fracturing osseous models is a challenge in computer graphics. The generation of bone fractures is important in the field of traumatology mainly for training. This field of research can provide specialists with a rich and varied amount of fracture cases. Traditionally, the generation of bone fractures has been carried out by using a finite element method (FEM) approach. Nevertheless, this approach requires a precise physical information of the model and the incoming forces that are not usually available. Thus, we propose a geometric approach to avoid these initial requirements. This paper evaluates the adequacy of a given generic destruction library (Blast) within the bone fracture generation context. Our aim is to assess its suitability to provide varied, uncommon cases and morphologically rich fractures in the field of bone fractures. In order to achieve quality results, bone models are evaluated at different scales, spanning from the macroscale to the nanoscale. This study highlights the advantages and shortcomings of the revised library. Additionally, it provides a groundwork for the use of this library in the context of fracturing osseous models as well as a set of addons needed to get a tool specifically designed for this aim.
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    A Modular Authoring Tool for Atmospheric Cloud Modelling
    (The Eurographics Association, 2022) Rodríguez-Hernández, Darío; García-Fernández, Ignacio; Posada, Jorge; Serrano, Ana
    Modelling of atmospheric effects and, in particular, of clouds is a recurrent topic in computer graphics. Achieving realistic results poses a great challenge, and manual modelling of such complex structures is unfeasible in production. The use of procedural techniques, either through simulation or heuristic methods, is, thus, frequent. In this work we propose a model that allows atmospheric cloud modelling with small computational effort and a good degree of control by the modeller, speeding up the artistic process. The model is designed hierarchically, can be extended easily due to its modular structure and it allows an intuitive control through a graphical user interface. The tests show a variety of effects that can be generated, and the influence of the different parameters on the render time of the final scene.