1	Introduction to 3D Geometric Graphics
2	Introduction to 3D 3D is much, much more complex and powerful than 2D Very brief history Basic concepts in 3D modeling and rendering Enough to be comfortable learning and using packages Highly technological and developed field of CG Video games, FX, are the drivers (more $$ than film) Visualization CAD/CAM, architecture Photorealism (imitating nature) was the original quest, now joined by NPR: cartoon physics, illustrative art and rendering What is a model? What is an image? How do we map from one to the other? CS15/16 or CS17/18 à CS123, CS224
3	"Before Sutherland’s 1963 Sketchpad" Before Sutherland’s 1963 Sketchpad, alphanumeric output via plotters/printers, input via keypunch, both in batch; some hacked “graphics” made with characters :>) Batch Computing (1950s – now)
4	"Almost all the key elements..." Almost all the key elements of interactive graphics system are expressed in the first paragraph of Sutherland’s 1963 Ph.D. thesis, entitled, Sketchpad, A Man-Machine Graphical Communication System: Today, still use batch mode for final production-quality video and film (special effects – fx), where one frame of a 24 fps movie may take 8-24 hours to render on the fastest PC!
5	"Graphics has been a key..." Graphics has been a key enabling technology in the evolution of computing environments: graphical user interfaces visual computing, e.g., desktop publishing of text and illustrations, scientific visualization, information visualization Hardware revolution drives everything every 12-18 months, computer power improves by factor of 2 in price / performance – Moore’s “Law” Wrist watches, cell phones, BlackBerry™, Treo™ 3Com Palm™ organizers, Compaq I-Paq™ as a full PC Hallmark singing card, LeapFrog™ Pad graphics memory and network speeds are on even faster exponentials Graphics chips improve dramatically every six to nine months (e.g. nVidia GeForce™ series, ATI Radeon™ series) due to huge competition between vendors
6	"Character Displays (1960s –..." Character Displays (1960s – now); bitmap raster graphics workstations and PCs from 1972 - now
7	Graphics Evolution (cont.)
8	"Primitive shapes (primitives" Primitive shapes (primitives) are manipulated with geometric transformations (translation, rotation, scale). These transformations are essential for model composition, the process of hierarchically composing complex objects from simpler components. Hierarchical models and the same geometric transformations are also essential for animation. Once object’s geometry is established, must be viewed on a screen. Must specify the “camera’s” PoV and map from 3D to 2D for viewing (and from 2D to 3D for 2D input devices (e.g., the mouse or pen/stylus)). In the process of mapping from 3D to 2D, object (surface) material properties and lighting effects are used in rendering one’s constructions. The rendering process is also called image synthesis.
9	"Divide and Conquer" Divide and Conquer Hierarchy of geometrical components Reduction to primitives (e.g., spheres, cubes, etc.) Simple vs. not-so-simple elements (nail vs. screw)
10	"The object to be modeled..." The object to be modeled is (visually) analyzed, and then decomposed into collections of primitive shapes. The tree diagram provides a visual method of expressing the “composed of” relationships of the model. Such diagrams are part of 3D program interfaces (e.g., 3D Studio MAX, Maya). Scenegraph: an internal representation of a geometric model, to be rendered
11	"The primitives created in the..." The primitives created in the decomposition process must be assembled to create the final object. This is done with transformations, T, R, S (as in the example above).
12	"Line segments" Line segments, polylines, polygons, polyhedra Triangles and tri-meshes
13	Example 3D Primitives 2/3 Curved surfaces with implicit or parametric equations (splines)
14	Example 3D Primitives 3/3c Platonic solids (and banana) Sweeps (aka “generalized cylinders, ducts”)
15	"Graphics library/package (e.g.,..." Graphics library/package (e.g., OpenGL™, DirectX ™) is intermediary between application and the display hardware (Graphics System) Application program maps application objects to views (images) of those objects by calling on graphics library User interaction results in modification of model and/or image Images are usually means to an end: synthesis, design, manufacturing, visualization,… This hardware and software framework is nearly 4 decades old but is still useful, indeed dominant
16	"Primitives (polygon" Primitives (polygon, polyhedron, triangle mesh…) Attributes color line style material properties for 3D Lights Transformations Camera
17	How Are Geometric Transformations (T,R,S) Used in Computer Graphics? Object construction using assemblies/hierarchy of parts à la Sketchpad’s masters and instances; leaves contain primitives Aid to realism objects, camera use realistic motion for animation