Abstract: An apparatus for texture mapping in a computer graphics system, using a predetermined set of standardized textures. Each texture of the standardized set is a procedural texture, and is supplied to the apparatus as one or a sequence of program commands the execution of which will result in the generation of the respective procedural texture. In a preferred embodiment, the means for processing the program commands comprises a processor operable to implement only those input program commands or sequences of input program commands as are required to generate the procedural textures of the standardized set.

Abstract: This paper discusses three distinct techniques for the animation of procedural textures and describes a software tool. Animation is attained by moving the rendered point before the texture evaluation, changing the definition of the texture space or changing the texture colour mapping. Examples are given for textures based on noise and turbulence functions in order to simulate natural phenomena. Some phases of the texture animation process can be automated using a code generator supported by a library of animation effects. Aspects of practical implementation are discussed and Renderman compliant code is presented.

Abstract: 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.

Abstract: Over the centuries artists and illustrators have developed techniques to effectively convey visual information. In this dissertation we develop the idea that we can apply these techniques to increase the expressive power of 3D computer graphics. This leads us to seek to build a unified free-form modeling system with which a designer can amplify her skills with pencil and paper to model both the geometry and stylized look of virtual scenes. In part I we first develop algorithms for rendering finely tessellated smooth surfaces in the style of simple line drawings, and at interactive rates. We next develop a procedural texture framework that lets us divide a model into distinct regions, with each rendered according to what it represents (bricks on the walls of a castle, say, but wood planks on the drawbridge). We then use this framework to develop two new classes of rendering algorithms—one class performs simple hatched shading, the other adopts techniques of the children's book illustrator Dr. Seuss (and others) to render fur, grass and trees in a stylized manner. In part II we focus on the problem of modeling a scene's geometry through an interface that leverages an artist's 2D drawing skills. We begin with a new technique for constructing 3D curves from 2D input: The user draws a curve and its shadow as both would appear from given viewpoint, and the system computes the corresponding 3D curve. We next describe new algorithm for computing a free-form surface that smoothly fits over a collection of “primitives” such as generalized cylinders or other “swept” objects. Our intention is to integrate the two techniques so that an artist can quickly sketch such primitives with the help of the first technique, then oversketch them with the second technique to produce the desired free-form surface. The natural next step is to integrate the various parts into a single system for sketching both 3D shapes and the stylized rendering algorithms used to depict them.

Abstract: In previous work [6], we presented an algorithm for rendering virtual scenes using art-based styles. We demonstrated the ability to render fur, grass, and trees in a stylized manner that evoked the complexity of these textures without representing all their components explicitly. We achieved this with stroke-based procedural textures that generated detail elements, or graftals, just as needed. Our implementation had several drawbacks. First, each new graftal texture required a procedural implementation that included writing code. Also, graftals were regenerated in each frame in a way that led to excessive introduction and elimination of graftals even for small changes in camera parameters. Lastly, our system provided no way to continuously vary the properties of graftals, including color, size, or stroke width. Such an ability could be used to achieve better frame-to-frame coherence, or more generally to animate graftals. In this paper, we present a new framework for graftal textures that addresses these issues. Our new framework allows all major decisions about graftal look and behavior to be specified in a text file that can be edited by a designer. We have achieved greater frameto-frame coherence by using graftals that remain in fixed positions on the model surface. The look and behavior of graftals as they appear or disappear can now be animated to create smooth transitions. Finally, we introduce the concept of tufts which manage the multiresolution behavior of graftals according to the specifications of the scene designer.

Abstract: This paper discusses volume scene graphs — a flexible hierarchical structure for composing scenes containing volume data sets and space-filling functions. Scene graph nodes are functions that, when evaluated at a point in space and time, compute and return a value. Typical nodes return values sampled from volume data sets, compute values using procedural texture algorithms, or filter and composite values returned by one or more other scene graph functions. Voxelization of a scene graph repeatedly evaluates the graph's functions over a gridded region of space. Examples are shown that compose scenes containing multiple volume data sets of differing resolutions and modalities.

Abstract: We present a procedural method for synthesizing large textures from an input texture sample. The basis of our algorithm is the chaos mosaic, a technique for synthesizing textures with an even and visually stochastic distribution of the local features of the input sample. The chaos mosaic is fast. For synthesizing textures of the same size and comparable quality, our algorithm is orders of magnitude faster than existing algorithms. On a PC we can synthesize a 512 X 512 texture from a 64 X 64 sample in just 0.03 seconds. More importantly, the chaos mosaic facilitates memory efficient texture rendering through procedural texturing. Like traditional solid texture techniques, the chaos mosaic allows us to synthesize and render synthetic textures that, if stored explicitly as textures, would require prohibitively large amounts of storage. As an example, we demonstrate that an 100k X 100k synthetic texture can be interactively visualized on a modest PC without suffering from latency. Finally, the chaos mosaic can drastically reduce the bandwidth for interactive 3D graphics delivered across the internet.

Abstract: With the advent of image based modeling techniques, it becomes easier to apply textures extracted from reality onto virtual worlds. Many repetitive patterns (structural textures) in human constructions can be parametrized with procedural textures. These textures offer a powerful alternative to traditional color textures, but they require the artist to program the desired effects. We present a system to automatically extract from photographs values for parameters of structural textures, giving the user the possibility to guide the algorithms. Two common classes of procedural textures are studied : rectangular tilings and wood. The results demonstrate that synthesizing textures similar to their real counterpart can be very interesting for computer-augmented reality applications.