Admission to CS 184 Enrollment priorities are 1. CS/EECS majors, 2. CS/EECS minors (this category includes applied math majors) 3. anyone else with a declared major.

The Rendering Pipeline V Instantiate and transform into World Coord.Syst. V Transform into Viewing Coord.System (VRCS) V Project into 2D Image Plane V Clip away geometry outside the Window V Transform to Screen Coordinates (pixels) V Rasterize Polygons, resolve Depth Priorities V MODEL GEOMETRY DISPLAY

Use of SLIDE Software How to do your assignments: Look at instructional pages and follow all the links, read explanations, study examples. Look at the SLIDE software provides; treat it as a resource, not as a straight-jacket. l Find out what is available (particularly all the executables !) l Study the overall approach and data structures (see how a competent programmer has coded it.) l If you like what you see,  use it. If not,  feel free to write your own code ! Every week you get a fresh start ! (no need to reuse your old code.)

Course Goals Gain Understanding ! -- not just skills in using graphics programs (Maya, Photoshop …)

Attenuation in Participating Media Light may get attenuated, colored as it travels through a not perfectly transparent medium. 181/25627/649/163/4

Scattering in Participating Media Part of the light may also get scattered away from its straight path and act as secondary light sources.

Photon Mapping – Pass #1 Emit many photons from all the light sources. Trace them to the first hit with a model surface. Statistically choose between: l Absorption: store the photon at that surface point; l Reflection: continue tracing photon to next surface. Actually, there are TWO Photon Maps: Global Photon Map: rough approximation of light flux in scene (like radiosity, but less expensive). Caustics Photon Map: store only light in caustics; created by sending very many photons towards specular or transparent (refractive) surfaces.

Photon Mapping – Pass #2 Rendering by Monte Carlo (statistical) ray tracing: Averaging a number of sample estimates: Send a ray through each pixel; where it hits the first surface, calculate radiance from the photon map stored nearby.

Trends in Computer Graphics Classical Computer Graphics (subject of CS184) takes a very “geometric” approach: ( transformations, projections! ). Newest rendering methods take an approach more based on statistical sampling (e.g. ray-cast). l The sampling density can be adaptively adjusted to fit the local spatial frequencies, the amount of light present, or the importance of the sampled feature to the overall picture quality. l The sampling rays can be randomly perturbed in their exact locations to reduce aliasing effects; they can be jittered in time to achieve motion blur.

Trends in Modeling Traditional l Polygons, splines, hard geometry; classical pipeline. l Implicit surfaces (spheres, tori) + CSG; ray-tracing. Newer Alternatives l Sampled data, voxels (MRI data, 3D scans, Ultrasound) l Particle systems (fire, smoke, fluids,...) Deformations, Dynamics, Breaking, Tearing … l Dynamically deformable geometry (bending, bouncing) l Finite element systems (FEM) l Stress and crack propagation l Fluid Dynamics (turbulence, shockwaves) Much Procedural Modeling …

Transparency: Use of Ray Tracing Can handle “directly” illuminated points L E

Transparency: Alpha Blending Composite the transparent polygons back-to-front L E

“Screen-Door” Transparency Only a subset of pixels are painted in Can give some order independency E

Transparency: A Difficult Scene Photon Mapping can handle this ! L