Final Project

Your final project is to produce a realistic image of a real object or scene. The scene or object should be challenging enough to require you to design and implement an advanced rendering algorithm. The final project is your chance to investigate an area that interests you in more depth, and to showcase your creativity. To get an idea of our expectations, check out the images produced by past participants. As extra incentive, we are offering a grand prize that includes a free trip to SIGGRAPH in Los Angelos in August for the best image produced. Think about following when choosing a project:

• What are your goals? Try and phrase this as specific questions that you would like to know the answers to, e.g. ``How do I model reflection from surfaces with fine geometric structure, such as fur?''
• What unique imagery would convincingly demonstrate that you have accomplished your goals? Try and keep this in mind throughout your project, since in computer graphics our work is often judged by the images we make.
• What has already been done in this area? You probably won't have time to completely investigate this, but you should definitely spend some time reading research papers. We can help you with finding appropriate references. When you read a paper, look for what has not been done as well as what is already understood; think about new things that you could try.
• Depending on the scope of your goals, you may want to work in a group. We encourage two person groups; larger groups will only be allowed to very, very challenging projects. Does your project split naturally into several pieces? Look for projects where each person's work is separable, and yet everyone contributes toward a shared goal that could not be accomplished individually.

Possible Projects

• Fancy primitives. Implement a class of more complicated primitives from Hanrahan's chapter in Glassner's book. Choose wisely. Quadrics you have already done; deformed surfaces are much more challenging. Recommended are subdivision surfaces, bicubic patches (display directly or by meshing), CSG models, or fractals. Fractals are relatively easy to implement and fun to use. For extra fun, map textures onto your patches or fractals. For lots of fun, try fur modeled as geometry (as opposed to as a volume).
  • bilinear patch
  • full CSG (legos)
  • partial CSG (indentations)
  • cone branches

• Exotic wavelength-dependent effects such as dispersion and thin film effects. We can give you some references.
  • thin-film interference (CD)
  • thin-film interference (prism)

• Adaptive stochastic supersampling. Use any sample distribution, subdivision criteria, and reconstruction method you like. Allow interactive control over key parameters of your sampling scheme. In a separate window alongside your rendered image, display a visualization of how many rays were cast per pixel.

• Texture mapping. Implement texture mapping for spheres, triangle meshes, and planar quadrilaterals (which you can represent as two triangles). Textures may be 2D or 3D, and may be procedurally generated, optically scanned, or borrowed from a friend. (There are unfortunately no scanners in Sweet Hall. There are two in the multimedia cluster at Meyer Library, one in Tressider, and one in the graphics lab in Gates 3B.) Avoid bilevel, severely quantized, or predithered textures; they will look poor when resampled - even if supersampled. Assuming you avoid extreme perspective views and implement some form of supersampling, you needn't bother with texture filtering at ray-surface intersections; your supersampling should eliminate most aliasing artifacts.

  Use your texture to modulate something besides just reflectance (i.e. color). Experiment with transparency, specularity, or orientation (i.e. bump mapping). Alternatively, try modulating an interpolation between two other textures or between two entirely different shading models. See Cook's Siggraph '84 paper on shade trees and Perlin's Siggraph '85 paper on texture synthesis (FvDFH, p. 1047) for ideas.

  For extra fun, implement texture filtering using direct convolution (section 17.4.2 of FvDFH) or prefiltering (using mip maps or summed area tables, section 17.4.3) to yield properly filtered textures without the need for supersampling. This will require comparing the u,v locations of adjacent rays to locally control the filter kernel size. If you implement this addon, you might need to adjust your sample region subdivision criteria in order not to supersample unnecessarily when rendering a textured surface.

  • color textures
  • color, shininess, and bump textures
  • 3D procedural textures
  • bump maps created with scanning
  • bump maps created with a custom program
  • more bump maps created with a custom program

• Subsurface scattering. Look at Hanrahan and Krueger's Siggraph '93 paper for examples of applying subsurface scattering to plants and faces. For the more ambitious, model the microgeometry of the surface. For example, consider an explicit geometric model of the warp and the weft of cloth, the pits in plaster, the scratches in metal, and the structure of velvet or satin. Ray trace the microgeometry in order to compute the brdf. Look at Westin et al. in SIGGRAPH '92; they describe methods for modeling carpet and velvet.

• Shading language. Develop a language for programmable shading formulas akin to (but simpler than) RenderMan's language (Hanrahan and Lawson, Siggraph '90). At a minimum, your language should allow the specification of a shade tree that includes mix nodes driven by textures as in Cook's Siggraph '84 paper on shade trees. Don't spend a lot of time on the interpreter - a simple syntax will do. For extra fun, implement (in conjunction with texture mapping) a nontrivial 2D or 3D texture synthesis method. Examples are spot-noise or reaction-diffusion equations (see the two papers on this subject in Siggraph '91).
  • complex shading formula
  • embedded shading language

• Monte Carlo ray tracing. Extend your area light source integrator into a full path tracer. Implement semi-diffuse reflections and refractions by distributing the secondary rays emanating from each surface according to a bidirectional reflectance distribution function (BRDF) of your own choosing. Look at Veach's paper on bidirectional ray tracing (Siggraph '90).
  • soft shadows (penumbrae), glossy surfaces
  • motion blur, depth of field

• Light ray tracing. Model caustics by tracing rays "backwards" from light sources and accumulating incident illumination as a texture on each surface. Implement the Wann Jensen's photon map algorithm. This one is harder, but we'll reward you suitably.
  • specular to diffuse transfer
  • caustics (glass)
  • caustics (pool)

• Volume rendering. Start by implementing spatially inhomogeneous atmospheric attenuation. Divide each ray into intervals. For each interval, interpolate between the ray's color and some constant fog color based on a procedurally computed opacity for that location in space. Experiment with opacity functions. Once you get this working, try defining a solid texture (probably procedurally) that gives color and opacity for each interval. See Perlin and Hoffert's Siggraph '89 paper on solid texture synthesis and Kajiya and Kay's teddy bear paper for ideas. If you want to make your volume renderer fast, use hierarchical spatial subdivision (e.g. an octree).
  • volumetric steam
  • hypertextured object

Project Proposal

The proposal should contain a picture of a real object or scene that you intend to reproduce. We suggest that you first pick something that you would like to simulate, and then investigate what techniques need to be used. A real object that you can carry around with you is best, but a good photograph or painting is almost as good.

This proposal should state the goal of your project, motivate why it is interesting, identify the key technical challenges you will face, and outline briefly your approach. If you are implementing an algorithm described in a particular paper, provide the reference to the paper. If you plan on collaborating with others, briefly describe how each person's piece relates to the others.

We will provide feedback as to whether we think your idea is reasonable, and also try to offer some technical guidance, e.g. papers you might be interested in reading.

Demo/Judgement Day

Grading

When you are finished with your project your should submit the source for your system and any test scenes and images that you have created. You should also submit your original project proposal, and an updated version that reads as a two to three page project summary, more or less of the same format as the project proposal, but with a brief results section and any conclusions or comments you have based on your experience.

You are permitted to work in small groups, but each person will be graded individually. A good group project is a system consisting of a collection of well defined subsystems. Each subsystem should be the responsibility of one person and be clearly identified as their project. A good criteria for whether you should work in a group is whether the system as a whole is greater than the sum of its parts!

Rendering Prize

• Grand Prize.

  An all-expense-paid trip to SIGGRAPH 2001 for one (worth about $800).

• First Prize.

  A software package such as photoshop or illustrator.

• Honorable Mentions.

  A book on rendering.