Silhouette Enhanced Point-Based Rendering (2009)
José Luiz Luz, Luiz Velho, Paulo Cezar, P. Carvalho
With the recent advances in the 3D scanning field, the size of datasets to be displayed has increased up to billions of points. Typically, we have a dense, unstructured set of points without...
Some Case Studies in Automatic Descriptor Extraction (2009)
Giordano Cabral, Jean-pierre Briot, Sergio Krakowski, Luiz Velho, François Pachet
Abstract. This work aims to evaluate the effectiveness of EDS as a tool to automatically extract descriptors for real-world problems, such as melody extraction, chord recognition, and sound...
• Image Matching and Transformation (2008)
Luiz Velho, From Szeliski, Luiz Velho Summer, Luiz Velho Summer
1. Take a sequence of images from the same position 2. Repeat for each image: – Compute transformation between current and next image – Shift the next image to overlap with the current image –...
A FRAMEWORK FOR REAL-TIME TERRAIN VISUALIZATION WITH ADAPTIVE SEMI- REGULAR MESHES (2008)
Lourena Rocha, Sérgio Pinheiro, Marcelo B. Vieira, Luiz Velho
Abstract: This work introduces a framework for large terrain data visualization using a highly expressive semi-regular mesh. The main advantage of this structure is that it can represent most objects...
Adaptive Deformable Models for Graphics and Vision † (2008)
Siome Goldenstein, Christian Vogler, Luiz Velho
Deformable models are a powerful tool in both computer graphics and computer vision. The description and implementation of the deformations have to be simultaneously flexible and powerful, otherwise...
Course Notes – SIGGRAPH 2003 Course Description (2008)
Luiz Velho (impa, Paulo Cezar, Pinto Carvalho, Luiz Velho
Mathematical optimization has a fundamental importance for the solution of many problems in computer graphics and vision. This fact is apparent from a quick look at the SIGGRAPH proceedings, where a...
Luiz Velho, Marcelo Bernardes Vieira, Jose Luiz, Soares Luz, Asla Sá, Paulo Cezar Carvalho
The advent of digital video caused a technological revolution that changed in many ways the audio-visual communications. The digital format is, by its very nature, robust to degradations and well...
Simple and E�cient Polygonization of Implicit Surfaces (2008)
his paper describes a simple and e�cient polygonization algorithm that gives a practical way to construct adapted piecewise linear representations of implicit surfaces. The method starts with a...
Restricted BPA: Applying Ball-Pivoting on the Plane (2008)
Esdras Medeiros, Luiz Velho, Helio Lopes
Abstract. In this article we propose a new 2D triangulation method based on the ball-pivoting algorithm (BPA). The BPA is an interesting advancing front approach for surface reconstruction that uses...
Geodesic Bézier Curves: a Tool for Modeling on Triangulations (2008)
Dimas Martínez, Morera Paulo, Cezar Carvalho, Luiz Velho
Figure 1. Modeling on the surface of a cow. From left: the control polygons of some curves and a C 1 spline, the corresponding curves, a region is filled and other is trimmed, final result. We define...
Expressive talking heads: A study on speech and facial expression in virtual characters (2008)
Paula Salgado Lucena, Marcelo Gattass, Luiz Velho
Abstract. This article presents the work carried out for a Master thesis and its main contributions. The thesis focuses on facial animation, more specifically on facial animations with...
A FRAMEWORK FOR REAL-TIME TERRAIN VISUALIZATION WITH ADAPTIVE SEMI- REGULAR MESHES (2008)
Lourena Rocha, Sérgio Pinheiro, Marcelo B. Vieira, Luiz Velho
Abstract: This work introduces a framework for large terrain data visualization using a highly expressive semi-regular mesh. The main advantage of this structure is that it can represent most objects...
Abstract Physically-Based Methods for Polygonization of Implicit Surfaces (2008)
Demetri Terzopoulos Z, Luiz Velho
We present discretephysically-based methods for generating polygonal approximations of implicit surfaces. These methods not only generate a combinatorial manifold approximating the surface, but also...
Adaptive Deformable Models for Graphics and Vision † (2008)
Siome Goldenstein, Christian Vogler, Luiz Velho
Deformable models are a powerful tool in both computer graphics and computer vision. The description and implementation of the deformations have to be simultaneously flexible and powerful, otherwise...
Polygonization of volumetric reconstructions from silhouettes Anselmo Antunes Montenegro (2008)
In this work we propose a method for the polygonization of octree-based reconstructions by dual contouring. Dual contouring is an adaptive method for determining contiguous polygonal meshes from...
UFRJ, Universidade Federal do Rio de Janeiro (2008)
Ricardo Marroquim, Paulo Roma Cavalcanti, Claudio Esperança, Luiz Velho
Abstract- This paper presents a method for generating multiresolution triangulations of non-manifold 3D objects composed of several regions with arbitrary geometry. The process of adapting the...
Stellar Subdivision Grammars (2008)
L. Kobbelt, P. Schröder, Luiz Velho, Matematica Pura Aplicada
In this paper we develop a new description for subdivision surfaces based on a graph grammar formalism. Subdivision schemes are specified by a context sensitive grammar in which production rules...
A Virtual Environment for 3D-Photography (2008)
Victor Bogado, Asla Sá, Luiz Velho
Abstract. This poster describes a virtual environment for 3D photography developed at the VISGRAF Lab.
Surface Reconstruction from Noisy Point Clouds (2008)
M. Desbrun, H. Pottmann (editors, Boris Mederos, Nina Amenta, Luiz Velho
We show that a simple modification of the power crust algorithm for surface reconstruction produces correct outputs in presence of noise. This is proved using a fairly realistic noise model. Our...
Ricardo Marroquim, Paulo Roma Cavalcanti, Claudio Esperanca, Luiz Velho
This paper presents a method for generating multi-resolution adaptive triangulations of non-manifold 3D objects composed of several regions with arbitrary geometry. The process rst immerses the input...
Adaptive Mesh Extraction using Simplification and Refinement (2008)
Adelailson Peixoto, Luiz Velho
Abstract. This work presents a method for multiresolution mesh extraction with important mathematical properties. The generated mesh represents a regular surface from 3D Euclidian space. The input...
Silhouette Enhanced Point-Based Rendering (2008)
José Luiz Luz, Luiz Velho, Paulo Cezar, P. Carvalho
With the recent advances in the 3D scanning field, the size of datasets to be displayed has increased up to billions of points. Typically, we have a dense, unstructured set of points without...
Analytical Features to Extract Harmonic or Rhythmic Information (2008)
Giordano Cabral, Jean-pierre Briot, Sergio Krakowski, Luiz Velho, François Pachet
Abstract. This work aims to evaluate the effectiveness of EDS as a tool to automatically extract descriptors for real-world problems, such as melody extraction, chord recognition, and sound...
Surface Reconstruction from Noisy Point Clouds (2008)
M. Desbrun, H. Pottmann (editors, Boris Mederos, Nina Amenta, Luiz Velho
We show that a simple modification of the power crust algorithm for surface reconstruction produces correct outputs in presence of noise. This is proved using a fairly realistic noise model. Our...
Histogram-Based HDR Video (2008)
in recent years. Technology advances consolidated this technique regarding software, hardware and applications. In terms of software, besides programs developed by pioneer researchers, such as...
GEncode: Geometry–driven compression in arbitrary dimension and co–dimension (2008)
Thomas Lewiner, Marcos Craizer, Hélio Lopes, Sinésio Pesco, Luiz Velho, Esdras Medeiros
attaches a triangle e ⊎ w to the active border edge e. w is identified by the circumradius ρ(e ⊎ w) of the original triangle which is divided by the length of e to be compact its histogram,...
Antônio W. Vieira, Thomas Lewiner, Luiz Velho, Hélio Lopes, Geovan Tavares
This paper introduces the Stellar Simplification scheme, a fast implementation of the Four–Face Cluster algorithm. In this scheme, a probabilistic optimization heuristic substitutes the priority...
Tracking and Matching Connected Components from 3D Video (2008)
Marcelo Bernardes Vieira, Luiz Velho
This work presents a method for the detection, tracking and spatial matching of connected components in a 3D video stream. The video image information is combined with 3D sites in order to align...
A Uni ed Approach for Hierarchical Adaptive Tesselation of Surfaces (2008)
This paper introduces a uni ed and general tesselation algorithm for parametric and implicit surfaces. The algorithm produces a hierarchical mesh that is adapted to the surface geometry and has a...
Adaptive Multi-Resolution Triangulations Based on Physical Compression (2008)
Ricardo Marroquim, Paulo Roma Cavalcanti, Claudio Esperança, Luiz Velho
This paper presents a method for generating multi-resolution adaptive triangulations of nonmanifold 3D objects composed of several regions with arbitrary geometry. The process first immerses the...
Fabiano Romeiro Harvard University Hardware-Assisted CSG Rendering (2008)
One of the most intuitive ways to model solid objects is by constructing them hierarchically, through combinations of simpler objects. Several representations that incorporate this paradigm exist, of...
Motion Reconstruction using Moments Analysis (2008)
Lourena Rocha, Luiz Velho, Paulo Cezar, P. Carvalho
Abstract. This paper presents a method for motion reconstruction. The approach is based on image moments and the bsp-tree data structure. We use invariant properties of these moments to construct a...
Volume xx (200y), Number z, pp. 1–10 GEncode: Geometry–driven compression for general meshes (2008)
Thomas Lewiner, Marcos Craizer, Hélio Lopes, Sinésio Pesco, Luiz Velho, Esdras Medeiros
Performances of actual mesh compression algorithms vary significantly depending on the type of model it encodes. These methods rely on prior assumptions on the mesh to be efficient, such as regular...
Approximating Parametric Curves with Strip Trees using Affine Arithmetic (2008)
Luiz Henrique, De Figueiredo, Jorge Stolfi, Luiz Velho
Abstract. We show how to use affine arithmetic to represent a parametric curve with a strip tree. The requiredbounding rectangles for pieces of the curve are computed by exploiting the linear...
Hierarchical isocontours extraction and compression (2008)
Thomas Lewiner, Hélio Lopes, Luiz Velho
Abstract. In this work, we introduce a new scheme to extract hierarchical isocontours from regular and irregular 2D sampled data and to encode it at single rate or progressively. A dynamic...
Luiz Velho, Ken Perlin, Estrada Dona Castorina
This paper describes an unbounded resolution paint system. The image is represented using a bi-orthogonal wavelet basis. The wavelet framework makes it possible to implement the necessary multiscale...
Some Case Studies in Automatic Descriptor Extraction (2008)
Giordano Cabral, Sergio Krakowski, Francois Pachet, Jean-pierre Briot, Luiz Velho, Giordano Cabral, ...
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores.
Abstract Synthesis of Progressively-Variant Textures on Arbitrary Surfaces (2008)
Jingdan Zhang, Tsinghua Univ, Kun Zhou, Luiz Velho
Permission to make digital/hard copy of part of all of this work for personal or classroom use is granted without fee provided that the copies are not made or distributed for profit or commercial...
L.: Hardware-assisted rendering of csg models (2008)
Current methods that interactively render reasonably complex CSG objects are image based and are severely bandwidth limited. This paper presents a new approach to raytracing CSG objects composed of...
M. Desbrun, H. Pottmann (editors, Simplicial Diffeomorphisms, Luiz Velho, Matemática Pura Aplicada
In this paper we introduce a new framework for geometric modeling that combines implicit and parametric surface representations with volumetric warpings. The framework is based on dynamic, adaptive...
Projective Texture Atlas Construction for 3D Photography (2008)
Luiz Velho, Jonas Sossai, Luiz Velho, Jonas Sossai
Abstract The use of attribute maps for 3D surfaces is an
Hardware-assisted CSG rendering (poster 0080) (2008)
One of the most intuitive ways to model solid objects is by constructing them hierarchically, through combinations of simpler objects. Several representations that incorporate this paradigm exist, of...
Geodesic Bézier Curves: a Tool for Modeling on (2008)
Dimas Martinez, Paulo Carvalho, Luiz Velho, Dimas Martínez, Morera Paulo, Cezar Carvalho, ...
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores.
Oriented Bounding Boxes Based on Multi-resolution Contours (2008)
Luis Rivera, Norte Fluminense, Paulo C. Carvalho, Luiz Velho
The determination of intersection or contact points between objects in interference is not a simple task. It could be time-consuming in a computer application. Generally, some real time applications...
Automatic 3D Facial Expression Editing in Videos (2008)
Ya Chang, Marcelo Vieira, Matthew Turk, Luiz Velho
In this paper, we introduce a novel framework for automatic 3D facial expression editing in videos. The system can replace any kind of expression with another one smoothly in 3D videos. We build a 3D...
VIDEO INTERPOLATION THROUGH GREEN’S FUNCTIONS OF MATCHING EQUATION (2008)
Perfilino Eugênio, Paulo Cezar, P. Carvalho, Luiz Velho
We propose a novel approach for generating video interpolating frames from optical flow information. Our approach is based on solving an affine image-matching equation via the Green’s function...
We show how to use affine arithmetic to represent a parametric curve with a strip tree. The required bounding rectangles for pieces of the curve are computed by exploiting the linear correlation...
L.: Hardware-assisted rendering of csg models (2008)
Current methods that interactively render reasonably complex CSG objects are image based and are severely bandwidth limited. This paper presents a new approach to raytracing CSG objects composed of...
Reconstructing Poisson Disc Samplings of Solid Objects with Topological Guarantees (2008)
Esdras Medeiros, Helio Lopes, Luiz Velho, Thomas Lewiner, Esdras Medeiros, Luiz Velho, ...
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores.
RANGE-ENHANCED ACTIVE FOREGROUND EXTRACTION (2008)
Asla Sá, Marcelo B. Vieira, Paulo Cezar Carvalho, Luiz Velho
We describe a new technique that uses active scene illumination to perform foreground-background segmentation and recover partial HDR information. We explore the fact that relative tones can be...
Expressive talking heads: A study on speech and facial expression in virtual characters (2008)
Paula Salgado Lucena, Marcelo Gattass, Luiz Velho
Abstract. This article presents the work carried out for a Master thesis and its main contributions. The thesis focuses on facial animation, more specifically on facial animations with...
Multi-Resolution Triangulations with Adaptation to the Domain Based on Physical Compression (2008)
Ricardo Marroquim, Paulo Roma Cavalcanti, Luiz Velho, Claudio Esperança
Abstract. This paper presents a method for generating multi-resolution triangulations of non-manifold objects composed of several regions with arbitrary geometry. The process of adapting the...
Tracking and Matching Connected Components from 3D Video (2008)
Marcelo Bernardes Vieira, Luiz Velho
This work presents a method for the detection, tracking and spatial matching of connected components in a 3D video stream. The video image information is combined with 3D sites in order to align...
Motion Cyclification by Time Frequency Warping (2008)
Fernando Wagner, Da Silva, Luiz Velho, Jonas Gomes, Siome Goldenstein
Abstract. This paper presents a new algorithm for the cyclification of 1D signals, based on a time frequency warping. The main goal is to preserve the basic characteristics of the signal, such as low...
Luiz Velho, Marcelo Bernardes Vieira, Asla Sá, Paulo Cezar Carvalho
The advent of digital video caused a technological revolution that changed in many ways the audio-visual communications. The digital format is, by its very nature, robust to degradations and well...
Color Halftoning with Stochastic Dithering and Adaptive Clustering (2008)
The reproduction of color images is a problem of great importance in business, scientific and industrial applications. A comprehensive overview of this problem can be found in [6]. Different areas,...
An Aspect Ratio Upper Bound in 2D Solid Alpha Complexes of Poisson Disc Samplings (2008)
Esdras Medeiros, Luiz Velho, Helio Lopes, Thomas Lewiner, Esdras Medeiros, Luiz Velho, ...
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores.
Abstract 4–8 Subdivision (2008)
In this paper we introduce 4–8 subdivision, a new scheme that generalizes the fourdirectional box spline of class � � to surfaces of arbitrary topological type. The crucial advantage of the...
Restricted BPA: Applying Ball-Pivoting on the Plane (2008)
Esdras Medeiros, Luiz Velho, Helio Lopes, Católica Rio Janeiro
In this article we propose a new 2D triangulation method based on the ball-pivoting algorithm (BPA). The BPA is an interesting advancing front approach for surface reconstruction that uses a ball of...
Motion Reconstruction using Moments Analysis (2008)
Lourena Rocha Luiz, Luiz Velho, Paulo Cezar, P. Carvalho
This paper presents a method for motion reconstruction. The approach is based on image moments and the bsp-tree data structure. We use invariant properties of these moments to construct a bsp-tree...
A New Interface Paradigm for Motion Capture Based Animation Systems (2007)
Fernando Wagner, Luiz Velho, Paulo Roma Cavalcanti
. This paper proposes a new user interface paradigm for motion capture based animation systems, providing intuitive and efficient ways to visualize the main motion capture concepts and operations. A...
An Architecture for Motion Capture Based Animation (2007)
Fernando Wagner, Serpa Vieira Silva, Luiz Velho, Paulo Roma Cavalcanti
. This paper proposes an architecture for motion capture based animation systems, that works with several data formats and uses the building block paradigm for motion processing operations. Also, a...
In this paper we present a method to construct networks of springmass elements describing the physical characteristics of geometric objects for dynamic simulations. The spring-mass meshes are...
We show how to use affine arithmetic to represent a parametric curve with a strip tree. The required bounding rectangles for pieces of the curve are computed by exploiting the linear correlation...
PANEL: Teaching Computer Graphics in Brazil (2007)
M. Walter, A. Frery, Léo P. Magalhães, Luiz Velho, Mestrado Computação, ...
Abstract. We present in this panel a collection of views and experiences about computer graphics teaching and education in Brazil. We hope this discussion will further development of guidelines and...
Volume xx (200y), Number z, pp. 1–7 Smooth Surface Reconstruction from Noisy Clouds (2007)
We describe a new method for surface reconstruction and smoothing based on unorganized noisy point clouds without normals. The output of the method is a refined triangular mesh that approximates the...
Asla M. Sá, Paulo Cezar Carvalho, Luiz Velho
In the last two decades the problem of accurately capturing the geometry of an object was extensively studied, while the acquisition of high-quality textures only in recent years has become subject...
We show how to use affine arithmetic to represent a parametric curve with a strip tree. The required bounding rectangles for pieces of the curve are computed by exploiting the linear correlation...
Jonas Gomes, Luiz Velho, Siome Klein Goldenstein
This paper discusses the problem of motion processing and proposes the use of a mathematical model, which describes a motion signal as a path with variable harmonic components. We show that this...
PUC–Rio — Laboratório Matmídia — Rio de Janeiro (2007)
Antônio W. Vieira, Luiz Velho, Hélio Lopes, Geovan Tavares, Thomas Lewiner, Unimontes Ccet, ...
Abstract. This paper introduces Stellar Simplification, a fast implementation of the Four–Face Cluster algorithm. In our version of this mesh simplification scheme, we adopt a probabilistic...
1 PUC–Rio — Laboratório Matmídia — Rio de Janeiro (2007)
Antônio W. Vieira, Luiz Velho, Hélio Lopes, Geovan Tavares, Thomas Lewiner
This paper introduces Stellar Simplification, a fast implementation of the Four–Face Cluster algorithm. In our version of this mesh simplification scheme, we adopt a probabilistic heuristic that...
Projective Texture Atlas Construction and Applications (2006)
Jonas Sossai, Luiz Velho, Luiz Velho, Jonas Sossai
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores.
MUAN: A Stop Motion Animation System (2006)
Margareth Varela, Luiz Velho, Bruno Madeira, Hedlena Bezerra, Marcos Magalhaes, Margareth Catoia Varela, ...
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores.
An Expressive Talking Head for an Interactive Storytelling System (2006)
Paula Salgado, Lucena Rodrigues, Cezar T. Pozzer, Bruno Feijo, Angelo Ciarlim, Antonio Furtado, ...
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores.
Chf: A scalable topological data structure for tetrahedral meshes (2005)
Marcos Lage, Thomas Lewiner, Hélio Lopes, Luiz Velho
Figure 1. Visualization of tetrahedral meshes using CHF. This work introduces a scalable topological data structure for manifold tetrahedral meshes called Compact Half– Face (CHF). It provides a...
Topological Mesh Operators (2005)
Luiz Velho, Helio Lopes, Esdras Medeiros, Thomas Lewiner, Geovan Tavares, Luiz Velho, ...
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores.
An image-based shading pipeline for 2d animation (2005)
Hedlena Bezerra, Bruno Feijó, Luiz Velho
Shading for cel animation based on images is a recent research topic in computer-assisted animation. This paper proposes an image-based shading pipeline to give a 3D appearance to a 2D character by...
Ya Chang, Marcelo Vieira, Matthew Turk, Luiz Velho
Abstract. We introduce a novel framework for automatic 3D facial expression analysis in videos. The preliminary results were demonstrated by editing the facial expression with facial recognition. We...
Ya Chang, Marcelo Vieira, Matthew Turk, Luiz Velho
Abstract. We introduce a novel framework for automatic 3D facial expression analysis in videos. Preliminary results demonstrate editing facial expression with facial expression recognition. We first...
Apresentações Hipermídia Apoiadas por uma Ferramenta de Animação Facial (2004)
Rogerio Rodrigues, Paula Lucena Rodrigues, Bruno Feijó, Luiz Velho, Luiz Fernando Soares
Rogério Ferreira Rodrigues, Paula Salgado, Lucena Rodrigues, Bruno Feijó, Luiz Velho, Luiz Fern, ...
Abstract. This paper describes the integration of a facial animation tool (Expressive Talking Heads- ETHs) with an adaptive hypermedia formatter (HyperProp formatter). This formatter is able to...
Hierarchical Isocontours Extraction and Compression (2004)
Thomas Lewiner, Luiz Velho, Helio Lopes, Vinicius Mello
In this work, we introduce a new scheme to extract hierarchical isocontours from regular and irregular 2D sampled data and to encode it at single rate or progressively. A dynamic tessellation is used...
Space Carving with a Hand-Held Camera (2004)
Anselmo Antunes Montenegro, Luiz Velho, Matemática Pura Aplicada, Marcelo Gattass
This paper presents a 3D scene reconstruction method, based on space carving, that works with a hand-held camera. In our system, the intrinsic and extrinsic parameters of the camera are determined at...
Adaptive Deformable Models (2004)
Siome Goldenstein Christian, Christian Vogler, Luiz Velho
Deformable models are a powerful tool in both computer graphics and computer vision. The description and implementation of the deformations have to be simultaneously flexible and powerful, otherwise...
Geodesic Paths on Triangular Meshes (2004)
Dimas Martnez Luiz, Luiz Velho, Paulo Cezar Carvalho
We present a new algorithm to compute a geodesic path over a triangulated surface. Based in Sethian's Fast Marching Method and Polthier's Straightest Geodesics theory, we are able to...
Simplicial Isosurface Compression (2004)
Thomas Lewiner, Luiz Velho, Hélio Lopes, Vinicius Mello
In this work, we introduce a new algorithm for direct and progressive encoding of isosurfaces extracted from volumetric data. A binary multi– triangulation is used to represent and adapt the 3D...
Asla Sa, Luiz Velho, Paulo Cezar Carvalho, Asla M. Sá, Luiz Velho, Paulo Cezar Carvalho
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores. HDR Radiance Maps have being widely studied in the...
4th Generation Video: Phase One (2004)
Luiz Velho, Marcelo Vieira, Asla Sa, Paulo Cezar Carvalho, Luiz Velho, Marcelo Bernardes Vieira, ...
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores.
Smooth surface reconstruction from noisy clouds (2004)
We describe a new method for surface reconstruction and smoothing based on unorganized noisy point clouds without normals. The output of the method is a refined triangular mesh that approximates the...
Stellar Mesh Simplification using Probabilistic Optimization (2004)
Antônio Wilson Vieira, Thomas Lewiner, Luiz Velho, Helio Lopes, Geovan Tavares
This paper proposes the Stellar Mesh Simplification method, a fast implementation of the Four–Face Cluster algorithm. In this method, a probabilistic optimization heuristic substitutes the priority...
Geodesic paths on triangular meshes (2004)
Dimas Martínez, Luiz Velho, Paulo Cezar Carvalho
Abstract. We present a new algorithm to compute a geodesic path over a triangulated surface. Based in Sethian’s Fast Marching Method and Polthier’s Straightest Geodesics theory, we are able to...
Adaptive deformable models (2004)
Siome Goldenstein, Christian Vogler, Luiz Velho
Abstract. Deformable models are a powerful tool in both computer graphics and computer vision. The description and implementation of the deformations have to be simultaneously flexible and powerful,...
Texture Blending to Point Sampled Geometry (2004)
Jose Luiz, Soares Luz, Paulo Cezar Carvalho, Luiz Velho, José Luiz Luz, Luiz Velho, ...
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores.
H.: Realistic, real-time rendering of ocean waves (2004)
Yaohua Hu, Luiz Velho, Xin Tong, Baining Guo, Harry Shum
In computer games and other real-time graphics applications, the ocean surface is typically modeled as a texture or bump-mapped plane with simple lighting effects. This paper describes a system for...
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores. Dynamic Adaptive Meshes and Stellar Theory In this...
Visualização de Terrenos em Tempo Real com Malhas Semi-Regulares (2004)
Luiz Velho, Lourena Rocha, Sergio Pinheiro, Marcelo Vieira, Lourena Rocha, Sergio Pinheiro, ...
The contents of this report are the sole responsibility of the authors. O conteúdo do presente relatório édeúnica responsabilidade dos autores.
Simplicial Isosurface Compression (2004)
Thomas Lewiner, Hélio Lopes, Luiz Velho
Abstract. In this work, we introduce a new algorithm for direct and progressive encoding of isosurfaces extracted from volumetric data. A binary multi–triangulation is used to represent and adapt...
Space Carving with a Hand-Held Camera (2004)
Anselmo Antunes Montenegro, Luiz Velho, Matemática Pura Aplicada, Marcelo Gattass
We present a 3D scene reconstruction method, based on space carving, that works with a hand-held camera. In our system, the intrinsic and extrinsic parameters of the camera are determined at the...
Rogério Ferreira Rodrigues, Paula Salgado, Lucena Rodrigues, Bruno Feijó, Luiz Velho, Luiz Fern, ...
Abstract. This paper describes the integration of a facial animation tool (Expressive Talking Heads- ETHs) with an adaptive hypermedia formatter (HyperProp formatter). This formatter is able to...
Moving Least Squares Multiresolution Surface Approximation (2003)
We describe a new method for surface reconstruction based on unorganized point clouds without normals. We also present a new algorithm for refining the inital triangulation. The output of the method...
A Topological Framework for Advancing Front Triangulation (2003)
Esdras Medeiros, Luiz Velho, Hélio Lopes
In this paper we study advancing front methods for surface reconstruction. We propose a topological framework based on handlebody theory to implement such methods in a simple and robust way. As an...
Algoritmo Ball-Pivoting : Contextualização e estado da arte / (2003)
Instituto de Matemática Pura e Aplicada.
H.: Moving least squares multiresolution surface approximation (2003)
Boris Mederos, Luiz Velho, Luiz Henrique, De Figueiredo
Abstract. We describe a new method for surface reconstruction based on unorganized point clouds without normals. We also present a new algorithm for refining the initial triangulation. The output of...
Moving Least Squares Multiresolution Surface Approximation (2003)
Boris Mederos Luiz, Luiz Velho, Luiz Henrique, De Figueiredo
We describe a new method for surface reconstruction based on unorganized point clouds without normals. We also present a new algorithm for refining the inital triangulation. The output of the method...
A topological framework for advancing front triangulations (2003)
Esdras Medeiros, Luiz Velho, Hélio Lopes, Católica Rio Janeiro
Abstract. In this paper we study advancing front methods for surface reconstruction. We propose a topological framework based on handlebody theory to implement such methods in a simple and robust...
Dynamic adaptive meshes (2003)
Abstract. In this paper we present dynamic adaptive meshes, a scheme for maintaining a conforming triangulation of time-varying surfaces. The user supplies an initial mesh, a surface sampling...
H.: Moving least squares multiresolution surface approximation (2003)
Boris Mederos, Luiz Velho, Luiz Henrique, De Figueiredo
Abstract. We describe a new method for surface reconstruction based on unorganized point clouds without normals. We also present a new algorithm for refining the inital triangulation. The output of...
A topological framework for advancing front triangulations (2003)
Esdras Medeiros, Luiz Velho, Hélio Lopes
Abstract. In this paper we study advancing front methods for surface reconstruction. We propose a topological framework based on handlebody theory to implement such methods in a simple and robust...
Connecting the Presence's Factors for Guiding Measurements (2003)
Antonia Lucinelma Pessoa, Pessoa Albuquerque, Rubens Melo, Luiz Velho
Introduction What does make us feel present in our real world/environment? It is natural to us to feel present where we are and with others, without being aware or thinking about this. The fact that...
H.: Robust smoothing of noisy point clouds (2003)
Abstract. This paper addresses the problem of removing the noise from noisy points clouds in the context of surface reconstruction. We introduce a new smoothing operator Q inspired by the moving...
Approximating parametric curves with strip trees using affine arithmetic (2002)
We show how to use affine arithmetic to represent a parametric curve with a strip tree. The required bounding rectangles for pieces of the curve are computed by exploiting the linear correlation...
Approximating parametric curves with strip trees using affine arithmetic (2002)
We show how to use affine arithmetic to represent a parametric curve with a strip tree. The required bounding rectangles for pieces of the curve are computed by exploiting the linear correlation...
Multiscale moment-based painterly rendering (2002)
In this paper we present a new method for painterly rendering of images.Our method extends the image-moment stroke placement algorithm in two ways: we employ a multiscale scheme for computing strokes...
Image moments-based structuring and tracking of objects (2002)
Lourena Rocha, Luiz Velho, Paulo Cezar Carvalho
This paper presents a new method for structuring and tracking of objects in video sequences. Our approach is based on image moments and the bsptree data structure. We use invariant properties of...
Multiscale Moment-Based Painterly Rendering (2002)
Diego Nehab, Luiz Velho, Multiscale Moment-based, Painterly Rendering
images. Our method extends the image-moment stroke placement algorithm in two ways: we employ a multiscale scheme for computing strokes and we provide a parametrized mechanism for controlling stroke...
Approximating Parametric Curves with Strip Trees using Affine Arithmetic (2002)
Luiz Henrique De, De Figueiredo, Jorge Stolfi, Luiz Velho
We show how to use affine arithmetic to represent a parametric curve with a strip tree. The required bounding rectangles for pieces of the curve are computed by exploiting the linear correlation...
Discrete scale spaces via heat equation (2001)
Anderson Cunha, Ralph Teixeira, Luiz Velho
Scale spaces allow us to organize, compare and analyse differently sized structures of an object. The linear scale space of a monochromatic image is the solution of the heat equation using that image...
Procedural shape synthesis on subdivision surfaces (2001)
Luiz Velho, Ken Perlin, Lexing Ying, Henning Biermann
We present methods for synthesizing 3D shape features on subdivision surfaces using multiscale procedural techniques. Multiscale synthesis is a powerful approach for creating surfaces with different...
Procedural shape synthesis on subdivision surfaces (2001)
Luiz Velho, Ken Perlin, Lexing Ying, Henning Biermann
Abstract. We present methods for synthesizing 3D shape features on subdivision surfaces using multiscale procedural techniques. Multiscale synthesis is a powerful approach for creating surfaces with...
Towards a unified framework for spatial data models (2000)
Câmara,Gilberto, Monteiro,Antônio Miguel Vieira, Paiva,João Argemiro, Gomes,Jonas, Velho,Luiz
This paper describes a unified framework for the problems of modelling and processing spatial entities. We propose a general definition of spatial objects, and show that the different types of...
Towards a unified framework for geographical data models (2000)
Gilberto Câmara, João Argemiro Paiva, Jonas Gomes, Luiz Velho
This paper describes a unified framework for the problems of modelling and processing geographical entities. We propose a general definition of geographical objects, and show that the different types...
Semi-regular 4-8 refinement and box spline surfaces (2000)
We introduce a new mesh refinement method for subdivision surfaces. It generates a semiregular 3-direction hierarchical structure from control meshes representing 2D manifolds of arbitrary topology....
Variable resolution 4-k meshes (2000)
We introduce variable resolution 4-k meshes, a powerful structure for the representation of geometric objects at multiple levels of detail. It combines most properties of other related descriptions...
Luiz M. Garcia, Fernando Da Silva, Antonio Oliveira, Luiz Velho, Jonas Gomes
. In this work we provide methodology to embed a motion-capture interface in a software control architecture, with which to implement artificial animated agents with more human like behavior. The...
Motion cyclification by time X frequency warping (1999)
Luiz Velho, Jonas Gomes, Siome Goldenstein
This paper presents a new algorithm for the cyclification of ID signals, based on a time X frequency warping. The main goal is to preserve the basic characteristics of the signal, such as low and...
Quasi 4-8 subdivision surfaces (1999)
This paper present a new scheme for subdivision surfaces that is based on four-directional meshes. It combines geometry-sensitive refinement with convolution smoothing. The scheme has a simple,...
Quasi 4-8 subdivision surfaces (1999)
Abstract. This paper presents a new scheme for subdivision surfaces that is based on four-directional meshes. It combines geometry-sensitive refinement with convolution smoothing. The scheme has a...
A unified approach for hierarchical adaptive tesselation of surfaces (1999)
This paper introduces a unified and general tesselation algorithm for parametric and implicit surfaces. The algorithm produces a hierarchical mesh that is adapted to the surface geometry and has a...
Motion Cyclification by Time × Frequency Warping (1999)
Luiz Velho, Fernando Wagner, Siome Goldenstein, Da Silva, Jonas Gomes
. This paper presents a new algorithm for the cyclification of 1D signals, based on a time \Theta frequency warping. The main goal is to preserve the basic characteristics of the signal, such as low...
IMPS: Implicit Surfaces for Interactive (1999)
Animated Characters Computer, Bruce M. Blumberg, Stephen A. Benton, Kenneth Bradley Russell, Kenneth Bradley Russell, Alex P. Pentland, ...
Implicit surface modeling in computer graphics is a powerful technique for representing smooth and organic shapes. Skeletal elements of an implicit surface blend to create a smooth, seamless skin...
Motion Cyclification by Time × Frequency Warping (1999)
Fernando Wagner, Da Silva, Luiz Velho, Jonas Gomes, Siome Goldenstein
This paper presents a new algorithm for the cyclification of 1D signals, based on a time # frequency warping. The main goal is to preserve the basic characteristics of the signal, such as low and...
TEXTURING COMPOSITE DEFORMABLE IMPLICIT OBJECTS (1998)
Zonenschein, Ruben, Gomes, Jonas, Velho, Luiz, DeFigueiredo, Luiz Henrique, Tigges, Mark, Wyvill, Brian
In this paper we present a method for applying 2D textures onto composite and articulated objects defined by implicit functions. The method generates a particle system associated with the gradient...
TEXTURING COMPOSITE DEFORMABLE IMPLICIT OBJECTS (1998)
Zonenschein, Ruben, Gomes, Jonas, Velho, Luiz, DeFigueiredo, Luiz Henrique, Tigges, Mark, Wyvill, Brian
In this paper we present a method for applying 2D textures onto composite and articulated objects defined by implicit functions. The method generates a particle system associated with the gradient...
Texturing composite deformable implicit objects (1998)
Ruben Zonenschein, Jonas Gomes, Luiz Velho, Luiz Henrique, De Figueiredo, Mark Tigges, ...
Abstract. In this paper we present a method for applying 2D textures onto composite and articulated objects defined by implicit functions. The method generates a particle system associated with the...
Texturing Composite Deformable Implicit Objects (1998)
Ruben Zonenschein, Jonas Gomes, Luiz Velho, Luiz Henrique, De Figueiredo, ...
. In this paper we present a method for applying 2D textures onto composite and articulated objects defined by implicit functions. The method generates a particle system associated with the gradient...
Um visualizador de panoramas matriciais (1997)
André Matos, Jonas Gomes, Luiz Velho
We present a program for visualizing image-based virtual panoramas which is part of the Visorama system, a new system for panorama based virtual environments. This viewer has similar functionality to...
An architecture for motion capture based animation (1997)
Luiz Velho, Paulo Roma Cavalcanti, Jonas Gomes
This paper proposes an architecture for motion capture based animation systems, which works with several data formats and uses the building block paradigm for motion processing operations. Also, a...
Color image quantization by pairwise clustering (1997)
This paper presents a new quantization method for color images. It uses a local error optimization strategy to generate near optimal quantization levels. The algorithm is simple to implement and...
A Methodology for Piecewise Linear Approximation of Surfaces (1997)
We discuss the problem of adaptive polygonization of regular surfaces of the euclidean 3D space, and present effective algorithms for computing optimal polygonizations of surfaces described in...
Color image quantization by pairwise clustering (1997)
Luiz Velho, Jonas Gomes, Marcos Vinicius, Rayol Sobreiro
Abstract. This paper presents a new quantization method for color images. It uses a local error optimization strategy to generate near optimal quantization levels. The algorithm is simple to...
Image effects using contractive mappings (1996)
Jonas Gomes, Cicero Mota, Luiz Velho
In this paper we exploit the power of contractive mappings to create special image effects. Under this framework,images are represented as the attractor of an Iterated Function System (IFS) and can...
Optimal adaptive polygonal approximation of parametric surfaces (1996)
We present a new method for adaptive polygonization of parametric surfaces. The method combines recursive simplicial subdivision of the domain and point sampling along curves on the surface. We avoid...
Optimal adaptive polygonal approximation of parametric surfaces (1996)
The polygonization of parametric surfaces is a classical problem in computer graphics and geometric modeling that has many practical applications. The problem is building a piecewise linear...
Optimal adaptive polygonal approximation of parametric surfaces (1996)
Luiz Velho, Luiz Henrique, De Figueiredo
Abstract. We present a new method for adaptive polygonization of parametric surfaces. The method combines recursive simplicial subdivision of the domain and point sampling along curves on the...
Optimal Adaptive Polygonal Approximation of Parametric Surfaces (1996)
. We present a new method for adaptive polygonization of parametric surfaces. The method combines recursive simplicial subdivision of the domain and point sampling along curves on the surface. We...
Jonas Gomes, Bruno Costa, Lucia Darsa, Luiz Velho
In this paper we introduce the concept of a graphical object, the abstraction paradigms to study them, as well as their applications in computer graphics. Intuitively, a graphical object encompasses...
Optimal adaptive polygonal approximation of parametric surfaces (1996)
Luiz Velho, Luiz Henrique, De Figueiredo
Abstract. We present a new method for adaptive polygonization of parametric surfaces. The method combines recursive simplicial subdivision of the domain and point sampling along curves on the...
Algorithmic modeling (or procedural modeling) is a recent research area in computer graphics which encompasses several methods extending traditional geometric modeling. Man-made objects are mostly...
SCRIPTS :--on the description of computer animated images /--byu Luiz Velho. (1985)
Supervised by Louis Zeltzer.
Texturing Composite Deformable Implicit Objects
Ruben Zonenschein Jonas, Jonas Gomes, Luiz Velho, Luiz Henrique, De Figueiredo, Mark Tigges, ...
. In this paper we present a method for applying 2D textures onto composite and articulated objects defined by implicit functions. The method generates a particle system associated with the gradient...