Djamchid Ghazanfarpour

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.

A Survey of Ocean Simulation and Rendering Techniques in Computer Graphics

This paper presents a survey of ocean simulation and rendering methods in computer graphics. To model and animate the ocean’s surface, these methods mainly rely on two main approaches: on the one hand, those which approximate ocean dynamics with parametric, spectral or hybrid models and use empirical laws from oceanographic research. We will see that this type of methods essentially allows the simulation of ocean scenes in the deep water domain, without breaking waves. On the other hand, physically‐based methods use Navier–Stokes equations to represent breaking waves and more generally ocean surface near the shore. We also describe ocean rendering methods in computer graphics, with a special interest in the simulation of phenomena such as foam and spray, and light’s interaction with the ocean surface.

Realistic real-time rain rendering

Abstract Real-time rendering of virtual weather conditions has been investigated in many papers. Inserting fog or snow in a scene is rather straightforward. Rain is one of the most encountered natural phenomena, but its rendering often lacks realism. In this paper, we propose a realistic real-time rain rendering method using programmable graphics hardware. In order to simulate the refraction of the scene inside a raindrop, the scene is captured to a texture which is distorted according to optical properties of raindrops. This texture is mapped onto each raindrop. Our method also takes into account retinal persistence, and interaction with light sources.

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.

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.

Ocean waves synthesis and animation using real world information

Abstract In Computer Graphics, existing ocean waves models still suffer from lack of realism and/or complexity of use essentially due to empirical definition of parameters by the user. In this paper, we propose an easy to use spectral ocean waves model whose parameters are obtained automatically from real world information. These parameters can be computed in two different ways. The first one makes use of measured oceanographic data and the second one is image based. Both are very fast and simple to use. By using real world information, we can achieve more realistic results than previous models. Ocean waves animation is very easy to perform with our spectral model. In addition, this model is procedural and allows a continuous representation of ocean surface away from shore with any size and any level of detail, while requiring very low memory storage.

A high-quality filtering using forward texture mapping

Abstract Texture mapping is a very popular technique used to provide more realism in image synthesis. Texture compression induced by geometric transformations creates serious aliasing artifacts appearing essentially as well-known “Moire” patterns. A simple and high-quality texture mapping technique using a forward mapping is presented. This new method very efficiently avoids texture aliasing artifacts by using an accurate convolution obtained naturally from forward mapping. In addition to a high-quality texture mapping, antialiasing of the final image contours is directly produced by this method.