Loic Barthe - Academia.edu (original) (raw)

Papers by Loic Barthe

Proceedings of the 21st ACM SIGGRAPH/EUROGRAPHICS symposium on Graphics hardware - GH '06, 2006

a) Penumbra wedge (b) Our algorithm (c) 1024-sample shadows (d) Difference between (a) and (c) (e... more a) Penumbra wedge (b) Our algorithm (c) 1024-sample shadows (d) Difference between (a) and (c) (e) Difference between (b) and (c) : A cube composed of 9 × 9 spheres. This scene illustrates the penumbra blending generated by different soft-shadow algorithms: the penumbra-wedges, our method and a reference image.

Rapport de recherche IRIT-2005-17- …, 2005

Page 1. A Sketch-Based Modelling system using Convolution Surfaces Anca Alexe1, Loıc Barthe1, Mar... more Page 1. A Sketch-Based Modelling system using Convolution Surfaces Anca Alexe1, Loıc Barthe1, Marie Paule Cani2, and Véronique Gaildrat1 1IRIT - CNRS, UPS Toulouse, France 2GRAVIR - CNRS, INRIA, UJS, INP Grenoble, France Abstract ...

… Workshop on Sketch-Based …, 2008

This paper presents Matisse, an interactive modeling system aimed at providing the public with a ... more This paper presents Matisse, an interactive modeling system aimed at providing the public with a very easy way to design free-form 3D shapes. The user progressively creates a model by painting 2D regions of arbitrary topology while freely changing the view-point and zoom factor. Each region is converted into a 3D shape, using a variant of implicit modeling that fits convolution surfaces to regions with no need of any optimization step. We use intuitive, automatic ways of inferring the thickness and position in depth of each implicit primitive, enabling the user to concentrate only on shape design. When he or she paints partly on top of an existing primitive, the shapes are blended in a local region around the intersection, avoiding some of the well known unwanted blending artifacts of implicit surfaces. The locality of the blend depends on the size of smallest feature, enabling the user to enhance large, smooth primitives with smaller details without blurring the latter away. As the results show, our system enables any unprepared user to create 3D geometry in a very intuitive way.

This paper presents a general framework for synchronising motion curves to music in computer anim... more This paper presents a general framework for synchronising motion curves to music in computer animation. Motions are locally modified using perceptual cues extracted from the music. The key to this approach is the use of standard music analysis techniques on complementary MIDI and audio representations of the same soundtrack. These musical features then guide the motion editing process. It allows

Computer Graphics Forum, 2002

Current methods for building models using implicit volume techniques present problems defining ac... more Current methods for building models using implicit volume techniques present problems defining accurate and controllable blend shapes between implicit primitives. We present new methods to extend the freedom and control- lability of implicit volume modeling. The main idea is to use a free-form curve to define the profile of the blend region between implicit primitives. The use of a free-form

Mathematics and Visualization, 2005

Lecture Notes in Computer Science, 2003

Computers & Graphics, 2015

Using 2D contour sketches as input is an attractive solution for easing the creation of 3D models... more Using 2D contour sketches as input is an attractive solution for easing the creation of 3D models. This paper tackles the problem of creating 3D models of animals from a single, side-view sketch. We use the a priori assumptions of smoothness and structural symmetry of the animal about the sagittal plane to inform the 3D reconstruction. Our contributions include methods for identifying and inferring the contours of shape parts from the input sketch, a method for identifying the hierarchy of these structural parts including the detection of approximate symmetric pairs, and a hierarchical algorithm for positioning and blending these parts into a consistent 3D implicit-surface-based model. We validate this pipeline by showing that a number of plausible animal shapes can be automatically constructed from a single sketch.

SIAM Journal on Scientific Computing, 2014

Many methods in computer graphics require the integration of functions on lowto-middle-dimensiona... more Many methods in computer graphics require the integration of functions on lowto-middle-dimensional spaces. However, no available method can handle all the possible integrands accurately and rapidly. This paper presents a robust numerical integration method, able to handle arbitrary non-singular scalar or vector-valued functions defined on low-to-middle-dimensional spaces. Our method combines control variate, globally adaptive subdivision and Monte-Carlo estimation to achieve fast and accurate computations of any non-singular integral. The runtime is linear with respect to standard deviation while standard Monte-Carlo methods are quadratic. We additionally show through numerical tests that our method is extremely stable from a computation time and memory footprint point-of-view, assessing its robustness. We demonstrate our method on a participating media voxelization application, which requires the computation of several millions integrals for complex media.

Proceedings of Graphics Interface 2007 on - GI '07, 2007

: An illuminated fabric with an acquired anisotropic velvet (left), isotropic wood (middle) and s... more : An illuminated fabric with an acquired anisotropic velvet (left), isotropic wood (middle) and shiny plastic (right) BRDF rendered at 40 FPS (512 × 512) using our wavelet encoding. The initial data sets containing 32 4 RGB samples (12MB) are compressed into 3D textures of 700KB. Our approach can be combined with classical texture, environment and bump mapping in order to produce high quality local illumination.

ACM Transactions on Graphics, 2014

We present a novel approach for interactive character skinning, which is robust when character mo... more We present a novel approach for interactive character skinning, which is robust when character movements are extreme, such as those involving contact between different parts of the skin and sharp bending angles at joints. Our approach builds on the basic idea of implicit skinning, namely approximate the character at each animation step by a 3D scalar field in which mesh-vertices are appropriately re-projected. Instead of being bound by an initial skinning solution, used to initialize the shape at each time step, we use the skin mesh to directly track iso-surfaces of the field over time. Technical problems are two-fold: firstly, all contact surfaces generated between skin parts should be captured as iso-surfaces of the implicit field; secondly, the tracking method should capture elastic skin effects when the joints bend, but also insure that the skin comes back to its rest shape when the character comes back to rest. Our solutions to these problems include: new composition operators enabling the combination of blending effects with local self-contact between implicit surfaces, and a tangential relaxation scheme derived from the as-rigid-as possible energy to solve the tracking problem. The result is a robust interactive system that can handle contacts in a way that is visually plausible, exhibits the global effect of skin elasticity (sliding), and is suitable for use in a production pipeline.

SIGGRAPH Asia 2011 Posters on - SA '11, 2011

International Journal of Shape Modeling, 2004

Potential functions allow the definition of both an implicit surface and its volume. In this repr... more Potential functions allow the definition of both an implicit surface and its volume. In this representation, two categories can be distinguished: bounded and unbounded representations. Boolean composition operators are standard modelling tools allowing complex objects to be built by the combination of simple volume primitives. Though they are well defined for the second category, there is no clear definition of the properties that such operators should satisfy in order to provide bounded representation with both smooth and sharp transition. In this paper, we focus on bounded implicit representation. We first present fundamental properties to create adequate composition operators. From this theoretical framework, we derive a set of Boolean operators providing union, intersection and difference with or without smooth transition. Our new operators integrate accurate point-by-point control of smooth transitions and they generate G 1 continuous potential fields even when sharp transition operators are used.

Proceedings of the 3rd international conference on Computer graphics, virtual reality, visualisation and interaction in Africa - AFRIGRAPH '04, 2004

Copyright © 2004 by the Association for Computing Machinery, Inc. Permission to make digital or h... more Copyright © 2004 by the Association for Computing Machinery, Inc. Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for commercial advantage and that copies bear ...

International Journal of Shape Modeling, 2001

This paper presents a new interpretation of the general definition of the binary blending operato... more This paper presents a new interpretation of the general definition of the binary blending operator of implicit modeling. Instead of considering the operator as a composition of potential functions or as a function defined in the combined primitives metric, we propose to consider it as an ...