Bump Mapping Research Articles

Generating textures on arbitrary surfaces using reaction-diffusion

This paper describes a biologically motivated method of texture synthesis called reaction-diffusion and demonstrates how these textures can be generated in a manner that directly matches the geometry of a given surface. Reaction-diffusion is a process in which two or more chemicals diffuse at unequal rates over a surface and react with one another to form stable patterns such as spots and stripes. Biologists and mathematicians have explored the patterns made by several reaction-diffusion systems. We extend the range of textures that have previously been generated by using a cascade of multiple reaction-diffusion systems in which one system lays down an initial pattern and then one or more later systems refine the pattern. Examples of patterns generated by such a cascade process include the clusters of spots on leopards known as rosettes and the web-like patterns found on giraffes. In addition, this paper introduces a method which reaction-diffusion textures are created to match the geometry of an arbitrary polyhedral surface. This is accomplished by creating a mesh over a given surface and then simulating the reaction-diffusion process directly on this mesh. This avoids the often difficult task of assigning texture coordinates to a complex surface. A mesh is generated by evenly distributing points over the model using relaxation and then determining which points are adjacent by constructing their Voronoi regions. Textures are rendered directly from the mesh by using a weighted sum of mesh values to compute surface color at a given position. Such textures can also be used as bump maps.

A method of generating stone wall patterns

Recently, several kinds of mapping technology, such as texture mapping and bump mapping, have played a very important role in the realization of more realistic image synthesis. The textures to be mapped are often obtained by using an optical scanner or a video camera. However, it is not easy to obtain a suitable image by taking a photo. We consider it very important to be able to generate a variety of textures and patterns easily according to the requirements. This paper proposes a new method of generating stone wall patterns as a specific case of a generalized texture generator. The advantage of the method is that it allows the user to generate a variety of stone wall patterns by specifying a few simple parameters. We have applied it to a visual simulation system in order to represent such stone textures as walls, pavements, and steps. This paper also gives some examples of its applications.

Cone-spheres

A cone-sphere consists of two spheres, together with the part of the cylinder or cone tangent to the two spheres and lying between them. Cone-spheres can be rapidly rendered with shading, highlights, texture, or bump maps, and composited to create twisted or branched tubular structures.

Direct WYSIWYG painting and texturing on 3D shapes

This paper describes a 3D object-space paint program. This program allows the user to directly manipulate the parameters used to shade the surface of the 3D shape by applying pigment to its surface. The pigment has all the properties normally associated with material shading models. This includes, but is not limited to, the diffuse color, the specular color, and the surface roughness. The pigment also can have thickness, which is modeled by simultaneously creating a bump map attached to the shape. The output of the paint program is a 3D model with associated texture maps. This information can be used with any rendering program with texture mapping capabilities. Almost all traditional techniques of 2D computer image painting have analogues in 3D object painting, but there are also many new techniques unique to 3D. One example is the use of solid textures to pattern the surface.

Horizon mapping: shadows for bump-mapped surfaces

Bump mapping produces realistic shading by perturbing normal vectors to a surface, but does not show the shadows that the bumps cast on nearby parts of the same surface. In this paper, these shadows are found from precomputed tables of horizon angles, listing, for each position entry, the elevation of the horizon in a sampled collection of directions. These tables are made for bumps on a standard flat surface, and then a transformation is developed so that the same tables can be used for an arbitrary curved parametrized surface patch. This necessitates a new method for scaling the bump size to the patch size. Incremental calculations can be used in a scan line algorithm for polygonal surface approximations. The errors in the bump shadows are discussed, as well as their anti-aliasing. (An earlier version of this article appeared as Max [10].)

Bidirectional reflection functions from surface bump maps

The Torrance-Sparrow model for calculating bidirectional reflection functions contains a geometrical attenuation factor to account for shadowing and occlusions in a hypothetical distribution of grooves on a rough surface. Using an efficient table-based method for determining the shadows and occlusions, we calculate the geometric attenuation factor for surfaces defined by a specific table of bump heights.Diffuse and glossy specular reflection of the environment can be handled in a unified manner by using an integral of the bidirectional reflection function times the environmental illumination, over the hemisphere of solid angle above a surface. We present a method of estimating the integral, by expanding the bidirectional reflection coefficient in spherical harmonics, and show how the coefficients in this expansion can be determined efficiently by reorganizing our geometric attenuation calculation.

Modeling the mighty maple

A method is presented for representing botanical trees, given three-dimensional points and connections. Limbs are modeled as generalized cylinders whose axes are space curves that interpolate the points. A free-form surface connects branching limbs. "Blobby" techniques are used to model the tree trunk as a series of non-circular cross sections. Bark is simulated with a bump map digitized from real world bark; leaves are textures mapped onto simple surfaces.

Optimization Theory and Applications

Introduction. Chapter 1: Introduction to mental ray. What Is mental ray? Why Use mental ray? The Structure of mental ray. mental ray Integration. Command-Line Rendering and the Stand-Alone Renderer. mental ray Shaders and Shader Libraries. Indirect Illumination. Chapter 2: Rendering Algorithms. Introduction to Synthetic Lighting. Rendering under the Hood. mental ray Rendering Algorithms. Scanline Rendering in Depth. Raytrace Rendering in Depth. Hardware Rendering. Chapter 3: mental ray Output. mental ray Data Types. The Frame Buffer. Frame Buffer Options. mental ray Cameras. Output Statements. Chapter 4: Camera Fundamentals. Camera Basics and Aspect Ratios. Camera Lenses. Host Application Settings. Chapter 5: Quality Control. Sampling and Filtering in Host Applications. Raytrace Acceleration. Diagnostic and BSP Fine-Tuning. Chapter 6: Lights and Soft Shadows. mental ray Lights. Area Lights. Host Application Settings. Light Profiles. Chapter 7: Shadow Algorithms. Shadow Algorithms. Raytrace Shadows. Depth-Based Shadows. Stand-Alone and Host Settings. Chapter 8: Motion Blur. mental ray Motion Blur. Motion-Blur Options. Motion-Blur Render Algorithms. Host Settings. Chapter 9: The Fundamentals of Light and Shading Models. The Fundamentals of Light. Light Transport and Shading Models. mental ray Shaders. Chapter 10: mental ray Shaders and Shader Trees. Installing Custom Shaders. DGS and Dielectric Shading Models. Glossy Reflection and Refraction Shaders. Brushed Metals with the Glossy and Anisotropic Shaders. The Architectural (mia) Material. Chapter 11: mental ray Textures and Projections. Texture Space and Projections. mental ray Bump Mapping. mental ray Projection and Remapping Shaders. Host Application Settings. Memory Mapping, Pyramid Images, and Image Filtering. Chapter 12: Indirect Illumination. mental ray Indirect Illumination. Photon Shaders and Photon-Casting Lights. Indirect Illumination Options and Fine-Tuning. Participating Media (PM) Effects. Chapter 13: Final Gather and Ambient Occlusion. Final Gather Fundamentals. Final Gather Options and Techniques. Advanced Final Gather Techniques. Ambient Occlusion. Chapter 14: Subsurface Scattering. Advanced Shading Models. Nonphysical Subsurface Scattering. An Advanced Shader Tree. Physical Subsurface Scattering. Appendix: About the Companion CD. Index.