Search results for " Computer Science"
showing 10 items of 3983 documents
From A Medial Surface To A Mesh
2012
Medial surfaces are well-known and interesting surface skeletons. As such, they can describe the topology and the geometry of a 3D closed object. The link between an object and its medial surface is also intuitively understood by people. We want to exploit such skeletons to use them in applications like shape creation and shape deformation. For this purpose, we need to define medial surfaces as Shape Representation Models (SRMs). One of the very first task of a SRM is to offer a visualization of the shape it describes. However, achieving this with a medial surface remains a challenging problem. In this paper, we propose a method to build a mesh that approximates an object only described by …
Curvilinear constraints for free form deformations on subdivision surfaces
2010
This paper presents a method to deform a subdivision surface with curvilinear constraints. It combines an intuitive free form deformation with a Loop subdivision algorithm. The main advantage of this method of deformation is that it uses only vertices of an object and satisfies the geometrical constraints provided by the user. It permits us to control the final shape of the deformed object, defining the range (i.e. the impact) of the deformation before applying it. The deformation takes into account the Loop properties to follow the subdivision scheme, allowing the user to fix some curvilinear constraints at the subdivision level he works on and to render the final object at the level he wa…
Human-Robot Cooperation for Surface Repair Combining Automatic and Manual Modes
2020
[EN] This article develops a human-robot cooperation to carry out treatments such as sanding, polishing, etc. on the surface of a known rigid object. For this purpose, a vision system is considered to get the object location to ensure not only the perpendicularity of the obot tool to the object surface but also a smooth approach of the tool to the surface. In order to add flexibility, the proposal includes the simultaneous combination of automatic and manual modes of operation. Thus, the human user can guide the robot tool to treat arbitrary areas (manual mode) and, when the operator releases the tool, the robot goes into the automatic mode to treat prior established areas. The method uses …
INITIAL PARAMETRIC REPRESENTATION OF BLOBS
2009
Blobs, developed by J.F. Blinn in 1982, are the implicit surfaces obtained by composition of a real numerical function and a distance function. Since, many authors (C. Murakami, H. Nishimura, G. Wyvill…) defined their own function of density, from these implicit surfaces are interesting from several points of view. In particular, their fusion makes it possible to easily obtain an implicit equation of resulting surface. However, these surfaces do not admit a parametric equation yet. In this article, we will establish the parametric equation of two blobs in fusion, defined by the function of density of C. Murakami, by using an algebraic method. Then, we will develop another method, based on …
H∞ sliding mode control for uncertain neutral-type stochastic systems with Markovian jumping parameters
2015
This paper is devoted to the investigation of H ∞ sliding mode control (SMC) for uncertain neutral stochastic systems with Markovian jumping parameters and time-varying delays. A sliding surface functional is firstly constructed. Then, the sliding mode control law is designed to guarantee the reachability of the sliding surface in a finite-time interval. The sufficient conditions for asymptotically stochastic stability of sliding mode dynamics with a given disturbance attenuation level are presented in terms of linear matrix inequalities (LMIs). Finally, an example is provided to illustrate the efficiency of the proposed method.
MULTIRESOLUTION ANALYSIS FOR IRREGULAR MESHES WITH APPEARANCE ATTRIBUTES
2004
We present a new multiresolution analysis framework based on the lifting scheme for irregular meshes with attributes. We introduce a surface prediction opera- tor to compute the detail coefficients for the geometry and the attributes of the model. Attribute analysis gives appearance information to complete the geomet- rical analysis of the model.We present an application to adaptive visualization and some experimental results to show the efficiency of our framework.
Multiresolution Analysis for Meshes with Appearance Attributes
2005
International audience; We present a new multiresolution analysis framework for irregular meshes with attributes based on the lifting scheme. We introduce a surface prediction operator to compute the detail coefficients for the geometry and the attributes of the model. Attribute analysis gives appearance information to complete the geometrical analysis of the model. A set of experimental results are given to show the efficiency of our framework. We present two applications to adaptive visual-ization and denoising.
3D shape extraction of internal and external surfaces of glass objects
2013
Three-dimensional (3D) digitization of manufactured objects has been investigated for several years and consequently, many techniques have been proposed. Even if some techniques have been successfully commercialized, most of them assume a diffuse or near diffuse reflectance of the object’s surface, and difficulties remain for the acquisition of “optically non cooperative” surfaces, such as transparent or specular ones. To address such surfaces, we propose a non conventional technique, called “Scanning from Heating” (SfH). In contrast to classical active triangulation techniques that acquire the reflection of visible light, we measure the thermal emission of the heated surface. The aim of th…
Comparison of leaf surface roughness analysis methods by sensitivity to noise analysis
2015
International audience; Surface roughness is of great interest in agricultural spraying because it is used to characterise leaf surface wettability to predict the behaviour of droplets on a leaf surface. In recent years, the use of texture analysis to estimate surface roughness has emerged. In this paper we propose to estimate leaf surface roughness by using an optimisation of the Generalized Fourier Descriptors method. This approach is then compared with two other standard methods in the literature, one based on grey level intensity variation and the other on wavelet decomposition. Since roughness has many definitions and each method is calculated differently, we propose a new approach to …
MUSIC-characterization of small scatterers for normal measurement data
2009
We investigate the reconstruction of the positions of a collection of small metallic objects buried beneath the ground from measurements of the vertical component of scattered fields corresponding to vertically polarized dipole excitations on a horizontal two-dimensional measurement device above the surface of the ground. A MUSIC reconstruction method for this problem has recently been proposed by Iakovleva et al (2007 IEEE Trans. Antennas Propag. 55 2598). In this paper, we give a rigorous theoretical justification of this method. To that end we prove a characterization of the positions of the scatterers in terms of the measurement data, applying an asymptotic analysis of the scattered fie…