Now showing items 21-40 of 51

    • Improved plane-sweep based algorithm for boundary extraction of 3D images 

      Ayala Vallespí, M. Dolors; Vergara, Enric (2005-09)
      External research report
      Open Access
      There exist several approaches to extract the boundary of a 3D image. Most of them represent the extracted boundary as a collection of a large number of little triangular or quadrangular faces whereas few approaches ...
    • Improved skeleton computation of extreme vertices encoded volume 

      Ayala Vallespí, M. Dolors; Rodríguez, J.; Thomas, F.; Vergara, E. (2006-06)
      External research report
      Open Access
      Many skeletonisation algorithms for discrete volumes have been proposed. The one given here can be fully implemented in terms of regularized boolean differences, unions and intersections of volumes, without relying on large ...
    • Improved virtual porosimeter 

      Vergés Garcia, Eduard; Ayala Vallespí, M. Dolors (2008)
      Conference report
      Restricted access - publisher's policy
      Recently, the term BioCAD has appeared to refer to the modeling of biological processes. This work focuses on the analysis of structural properties such as porosity of bioimplants for bone reconstruction. Specifically, ...
    • MDCO to B-Rep conversion algorithm 

      Ayala Vallespí, M. Dolors; Andújar Gran, Carlos Antonio; Brunet Crosa, Pere (1995-07)
      External research report
      Open Access
      Spatial enumeration models are widely used in several fields. These models are approximate but the major disadvantage is the lack of concision. In order to avoid such verbosity, hierarchical encodings such as octrees have ...
    • Merging faces: A new orthogonal simplification of solid models 

      Cruz Matías, Irving Alberto; Ayala Vallespí, M. Dolors (Springer, 2013)
      Conference report
      Restricted access - publisher's policy
      A new approach to simplify orthogonal pseudo-polyhedra (OPP) and binary volumes is presented. The method is incremental and produces a level-of-detail (LOD) sequence of OPP. Any object of this sequence contains the ...
    • Modelat sòlid: realització d'operacions booleanes amb model de fronteres 

      Ayala Vallespí, M. Dolors (1989)
      External research report
      Open Access
      Aquest treball presenta un algorisme per realitzar operacions booleanes amb model de fronteres. Es basa en un algorisme en 2D per polígons. L'algorisme consta de 4 passos. Els tres primers son comuns a qualsevol operació ...
    • Multiresolution approximation of polyhedral solids 

      Ayala Vallespí, M. Dolors; Brunet Crosa, Pere; Joan Arinyo, Robert; Navazo Álvaro, Isabel (1996-06)
      External research report
      Open Access
      Multiresolution models with different levels of detail are a basic tool for handling very large and complex systems in computer aided design applications such as ship design. In this work, we discuss several automatic ...
    • Object representation by means of nonminimal division quadtrees and octrees 

      Ayala Vallespí, M. Dolors; Brunet Crosa, Pere; Juan, R.; Navazo Álvaro, Isabel (1985-01)
      Article
      Restricted access - publisher's policy
      Quadtree representation of two-dimensional objects is performed with a tree that describes the recursive subdivision of the more complex parts of a picture until the desired resolution is reached. At the end, all the leaves ...
    • Octree simplification of polyhedral solids 

      Ayala Vallespí, M. Dolors; Brunet Crosa, Pere (1995-02)
      External research report
      Open Access
      Multiresolution representations are becoming more and more important for the visualization, operation and interrogation of very complex scenes. In this paper, an automatic simplification algorithm for general two-manifold ...
    • Orientation, sphericity and roundness evaluation of particles using alternative 3D representations 

      Cruz Matías, Irving; Ayala Vallespí, M. Dolors (2014)
      External research report
      Open Access
      Sphericity and roundness indices have been used mainly in geology to analyze the shape of particles. In this paper, geometric methods are proposed as an alternative to evaluate the orientation, sphericity and roundness ...
    • Orthogonal polyhedra as geometric bounds in constructive solid geometry 

      Aguilera, A; Ayala Vallespí, M. Dolors (1996-12)
      External research report
      Open Access
      Set membership classification and, specifically, the evaluation of a CSG tree are problems of a certain complexity. Several techniques to speed up these processes have been proposed such as Active Zones, Geometric ...
    • Quantitative analysis of the resorption and osteoconduction of a macroporous calcium phosphate bone cement for the repair of a critical size defect in the femoral condyle 

      Miño Fariña, Natalia; Muñoz Guzón, Fernando; López Peña, Mónica; Ginebra Molins, Maria Pau; Valle Fresno, Sergio del; Ayala Vallespí, M. Dolors; González Cantalapiedra, Antonio (Elsevier, 2009-02)
      Article
      Restricted access - publisher's policy
      Clinical orthopaedic use of calcium phosphate cement has been limited due to its slow resorption rate, but a new macroporous a-tricalcium phosphate (a-TCP) bone cement has been designed to accelerate resorption and to ...
    • Representation and boundary extraction of a 3D digital image using the EVM model 

      Ayala Vallespí, M. Dolors; Aguilera Ramírez, Fernando Antonio; Rodríguez Rojas, Jorge Ernesto (2000-11)
      External research report
      Open Access
      In recent published papers we have presented the Extreme Vertices Model (EVM), a concise and complete model for representing orthogonal polyhedra. This model exploits the simplicity of its domain by allowing robust and ...
    • Robust topology simplification 

      Andújar Gran, Carlos Antonio; Brunet Crosa, Pere; Ayala Vallespí, M. Dolors (2000-05)
      External research report
      Open Access
      This paper deals with simplification algorithms for generating coarse-level approximations of both geometrically and topologically complex models. Our main contribution is a new framework called DPS which models a family ...
    • Skeleton computation of an image using a geometric approach 

      Martínez Bayona, Jonás; Vigo Anglada, Marc; Pla García, Núria; Ayala Vallespí, M. Dolors (2010)
      Conference lecture
      Restricted access - publisher's policy
      In this work we develop two algorithms to compute the skeleton of a binary 2D image. Both algorithms follow a geometric approach and work directly with the boundary of the image which is an orthogonal polygon (OP). One ...
    • Skeleton computation of an image using a geometric approach 

      Martínez Bayona, Jonàs; Vigo Anglada, Marc; Pla García, Núria; Ayala Vallespí, M. Dolors (2010-03)
      External research report
      Open Access
      In this work we develop two algorithms to compute the skeleton of a binary 2D images. Both algorithms follow a geometric approach and work directly with the boundary of the image wich is an orthogonal polygon (OP). One of ...
    • Skeletonless porosimeter simulation 

      Rodríguez, Jorge; Cruz Matías, Irving; Vergés Garcia, Eduard; Ayala Vallespí, M. Dolors (2010)
      External research report
      Open Access
      We introduce a new approach to simulate a virtual mercury intrusion porosimetry (MIP) using neither skeleton computing nor seed-growing methods. Most of the existing methods to determine local pore sizes in a porous medium ...
    • Solving point and plane vs. orthogonal polyhedra using the extreme vertices model (EVM) 

      Aguilera, Antonio; Ayala Vallespí, M. Dolors (1997-12)
      External research report
      Open Access
      In a previous work, Orthogonal Polyhedra (OP) were proposed as geometric bounds in CSG. Primitives in the CSG model were approximated by their respective bounding boxes. The polyhedrical bound for the CSG object was ...
    • Sphericity and roundness computation for particles using the extreme vertices model 

      Cruz Matías, Irving; Ayala Vallespí, M. Dolors; Hiller, Daniel; Gutsch, Sebastian; Zacharias, Margit; Estradé, Sònia; Peiró Martínez, Francesca (Elsevier, 2019-01-01)
      Article
      Open Access
      Shape is a property studied for many kinds of particles. Among shape parameters, sphericity and roundness indices had been largely studied to understand several processes. Some of these indices are based on length measurements ...
    • Splat representation of parametric surfaces 

      Ayala Vallespí, M. Dolors; Pla García, Núria; Vigo Anglada, Marc (2005-09)
      External research report
      Open Access
      Point-based geometry representations and their splat-based generalizations have become a suitable technique both for modeling and rendering complex 3D shapes. So, it seems interesting to convert other kind of models to ...