Jean-Michel Dischler

Generation of 3D texture using multiple 2D models analysis

Solid (30) texturing is commonly used in computer graphics for producing more realistic images. It is often more attractive than the conventional 20 texture mapping but remains more complex on some points. Its major difficulty concerns the generation of 30 texture in a general and efficient way. The well‐known traditional procedural methods use generally a simplified mathematical model of a natural texture. No reliable way for the choice of the mathematical model parameters, which characterise directly the produced 30 texture, is given. Therefore, 30 texture generation becomes a more or less experimental process with these methods.

Ocean waves synthesis using a spectrum-based turbulence function

The representation of ocean waves is not a resolved problem in computer graphics yet. There is still no existing method that allows one to simply describe an agitated surface of any size that is visually sufficiently realistic, without using entirely physical models that are usually very complex. We present a simple method to represent and animate an ocean surface in deep water by considering it as a procedural texture. This texture is defined by a combination of two levels of detail. The first one is a superposition of 2D trochoids whose parameters are determined by ocean wave characteristics infrequency domain. In order to increase the visual complexity of this model and to reduce computation, we incorporate a 3D turbulence function to provide a second level of detail. This turbulence function is also determined by frequency characteristics of ocean waves. Since our synthesized ocean waves spectrum approaches a real ocean waves spectrum, we obtain realistic water waves in the spatial domain. The animation of our model is performed by shifting the phase of the trochoids and by moving into the 3D turbulence function. Since our definition is procedural and continuous, it permits us to obtain any size of water surface with any level of detail as well as a simple, direct, antialiasing method. Our model can be used to generate ocean waves using 2D textures or bump maps as well as 3D textures.

Interactive image-based modeling of macrostructured textures

This article addresses the modeling aspects of macrostructured texture synthesis often avoided by other methods. We aim to develop a system that provides an intuitive, interactive, continuous, and easy-to-use control to users during the entire synthesis process. Therefore, we propose efficient new solutions for the following four problems: interactive and easy control of the macrostructure attributes; easy specification of the shapes; controlled deformations and interactions to avoid repetitions. In particular, we use a random technique, which is an important factor in getting more natural-looking structures; use of digitized texture pictures as natural models to guide the synthesis and obtain high-quality results.

Efficiently Rendering Macro Geometric Surface Structures with Bi-Directional Texture Functions

Fast and realistic rendering of textures, characterised by a pronounced geometry, such as for example wickerwork, rattan or beach pebbles, is still a difficult and challenging problem in computer graphics. These effects can neither be simulated with 2D texture mapping nor with bump mapping. Direct geometric models or “volumetric” texturing approaches often become inevitable. All of them, however, imply excessive computational requirements. In this paper, the concept of bi-directional texture function (BTF) is introduced. A BTF permits a realistic simulation of the above mentioned effects at very low computational cost. Principles generally applied at microscale in the case of BRDFs are transposed at larger geometric scale. This allows us a direct generalisation of texture mapping and leads to many visual simulations beyond the possibilities of usual “fast” texturing techniques.

A survey of 3D texturing

Abstract Texturing is indispensable for the realistic rendering since it adds surface details that are usually too complex to be modeled directly. Conventional 2D texture mapping remains the most usual approach to texturing, in particular for real-time applications. However, there are some major drawbacks inherent to this approach: the distortion and the discontinuity of textures as well as the lack of the “third” dimension information (geometric effects like roughcast cannot be rendered). 3D texturing has been introduced to computer graphics to resolve these problems. There are two types of 3D texturing: solid texturing that consists of defining color variations through the entire 3D space instead of the 2D one and geometric texturing that consists of adding a “real” third dimension information to surfaces in the form of “real” apparent geometry. This paper presents a detailed survey of 3D texturing. Main principles, advantages, drawbacks and applications are presented. The crucial problem of 3D textures synthesis is studied with a particular attention to analytical methods as well as physical-based models that can provide interesting solutions to this problem.

A Procedural Description of Geometric Textures by Spectral and Spatial Analysis of Profiles

In this paper we describe a method for automatically generating procedural “geometric” textures, using a hybrid (spectral and spatial) analysis of profiles (ID curves). The profile describes a certain height variation for a certain abscissa. We call “geometric” textures a class of textures including “Bump” textures and “hypertextures”. In dealing with this challenge (automatic synthesis), we introduce two new key ideas.

Real-time high-quality View-Dependent Texture Mapping using per-pixel visibility

We present an extension of View-Dependent Texture Mapping (VDTM) allowing rendering of complex geometric meshes at high frame rates without usual blurring or skinning artifacts. We combine a hybrid geometric and image-based representation of a given 3D object to speed-up rendering at the cost of a little loss of visual accuracy.During a precomputation step, we store an image-based version of the original mesh by simply and quickly computing textures from viewpoints positionned around it by the user. During the rendering step, we use these textures in order to map on the fly colors and geometric details onto the surface of a low-polygon-count version of the mesh.Real-time rendering is achieved while combining up to three viewpoints at a time, using pixel shaders. No parameterization of the mesh is needed and occlusion effects are taken into account while computing on the fly the best viewpoints for a given pixel. Moreover, the integration of this method in common real-time rendering systems is straightforward and allows applying self-shadowing as well as other z-buffer effects.

Interactive refraction on complex static geometry using spherical harmonics

Accurate refraction, thanks to raytracing, has always been a popular effect in computer graphics imagery. However, its use has been severely hindered in interactive rendering due to the lack of efficient and realistic techniques geared toward polygon oriented rendering.In this paper, a method to achieve realistic and interactive refractive effects through complex static geometry is proposed. It relies on an offline step where many light paths through the object are pre-evaluated. During rendering, these precomputed paths are used to provide approximations of actual refracted paths through the geometry, enabling further sampling of an environment map. Light paths valuable information, namely final output direction when leaving refractive object, is compressed using frequency domain based spherical harmonics. The matching decompression procedure, entirely offloaded onto graphics hardware, is handled at interactive speed.

A Geometrical Based Method for Highly Complex Structured Textures Generation

Conventional 2D or 3D texturing methods do not permit an efficient simulation of highly complex structured textures like fire, fur, cotton, etc. More recent techniques, using specific kinds of 3D textures, such as hypertextures or texels based on volume rendering algorithms, are more interesting, for the simulation of such special types of textures. Unfortunately, these techniques remain still restricted because either they need a functional modelling of the object, as it is the case of hypertextures, or they are strictly limited to one specific kind of texture, as it is the case of texels.

On-the-fly multi-scale infinite texturing from example

In computer graphics, rendering visually detailed scenes is often achieved through texturing. We propose a method for on-the-fly non-periodic infinite texturing of surfaces based on a single image. Pattern repetition is avoided by defining patches within each texture whose content can be changed at runtime. In addition, we consistently manage multi-scale using one input image per represented scale. Undersampling artifacts are avoided by accounting for fine-scale features while colors are transferred between scales. Eventually, we allow for relief-enhanced rendering and provide a tool for intuitive creation of height maps. This is done using an ad-hoc local descriptor that measures feature self-similarity in order to propagate height values provided by the user for a few selected texels only. Thanks to the patch-based system, manipulated data are compact and our texturing approach is easy to implement on GPU. The multi-scale extension is capable of rendering finely detailed textures in real-time.