Now showing items 21-40 of 49

  • 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 ...
  • 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
    Restricted access - publisher's policy
    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 ...
  • Structural parameters 

    Ayala Vallespí, M. Dolors; Vergés, Eduard (2010-02)
    External research report
    Open Access
    The development of the bioengineering field has yield to the apparition of a new application of the Computer-Aided-Design, Bio-CAD, aiming to the use of computer models to represent biological samples and methods to simulate ...