1. 3D Graphics Glossary
PART 2

2. Modeling Construction of geometric objects in 3D scenes.
Models describe the forms of objects, but not their material properties or how they move.

3. Node
In computer science, a node is an abstract container of information.
Nodes generally have attributes that store data.
In a 3D graphics program, nodes are connected together to form a network called a scene graph. 
For example, in Maya, a primitive object such as a Sphere is made of three nodes, each storing a different type of data: a primitive node, a shape node, and a transform node.

4. NURBS Non-Uniform Rational Basis Spline.
A particular type of spline curve with weighted control points.
Compare to Bezier spline.

5. Orthographic projection
A flat, 2D view of a 3D object or scene.
Technical drawings, blueprints and floor plans are examples of orthographic projections.
In 3D programs, orthographic views such as Front, Top, and Side are common.
Orthographic views are always aligned with the axes of the world Cartesian coordinate system.

6. They are necessary because 3D perspective views always introduce visual distortions of object size, placement and/or distance.
An ortho view is unlike a perspective view, because an ortho view shows no indication of distance or depth.
In a perspective view, an object is displayed smaller as it moves away from the viewer.

7. Parallel lines appear to converge at a vanishing point.
Simulated rays of light from the 3D scene, called lines of projection, all converge at the virtual camera lens.
In an ortho view, the size of an object in the view does not depend on its distance.
Two objects of the same size are drawn the same size on the screen, no matter how far away they are.
Parallel lines remain parallel, and do not converge.
The lines of projection are at right angles to the screen.

8. Particle system
A type of procedural animation that reproduces the appearance of fuzzy phenomena such as clouds or fire.
Particle systems may also be employed to animate many objects in a scene, such as a flock of birds.

9. Patch
A deformable parametric surface, useful for creating curved objects.
It can be based on Bezier or NURBS mathematics.
The curvature is controlled by the position of control vertices.

10. Perspective
Representation of a scene in which parallel lines are depicted as converging, in order to give the illusion of depth and distance.
Like an orthographic view, a perspective view is a projection of a 3D scene onto a 2D screen.
However, in a perspective view, the lines of projection converge on a virtual camera, which is the simulated point of view.

11. Pivot point
The center of an object’s transforms, and the center of its local coordinate system.
An object moves, rotates, and scales relative to the location and orientation of its pivot point.
Also known as "anchor point" in some computer applications.

12. Pixel
Abbreviation of picture element: the smallest possible element of a picture.
A digital image is defined by a discrete number of pixels arranged in a 2D grid or mosaic.
Many very small pixels blend together in the human eye and brain to give the illusion of a continuous, unbroken image.

13. Pixel ratio The proportion of pixel width to pixel height.
In most cases, pixels are square, giving a pixel ratio of 1 to 1.
However, some formats use non-square pixels, such as DVDs, which have a pixel ratio of 0.9 to 1.
This can cause headaches when working with non-square pixel formats on hardware that only displays square pixels.
All desktop computers use square pixels to display their graphical user interface.

14. Polygon A closed 2D plane figure bounded by straight line edges.
Polygons can be connected to one another in 3D space to create mesh objects.
In some computer graphics applications, faces and polygons are synonymous, but sometimes the term face refers specifically to a triangle.
A polygon is composed of one or more triangles which all lie in the same plane.
For example, a square polygon is made up of two triangular faces.

15. Procedural
An algorithm which generates data within the 3D graphic application.
For example, procedural 3D textures are patterns which do not require mapping coordinates.
Procedural animation generates motion, and may not involve keyframes at all.
Procedural modeling employs simple rules to generate complex structures such as plants.
Maya's Paint Effects is a superb example of a tool for procedural modeling and animation.

16. Progressive scan
A video display mode which draws each scanline (row of pixels) sequentially, and does not use alternating fields.

17. Radiosity
Rendering which accurately simulates the propagation of light energy throughout an environment.
Radiosity works by calculating the effects of light bouncing off of objects to illuminate other objects.
It is a global illumination algorithm, meaning it accounts for the ways in which light is transferred among surfaces in the scene.

18. Raster image
A 2D image which is composed of a series of horizontal scanlines arranged in vertical rows.
Digital raster images are comprised of a grid matrix of pixels.
All bitmap images are raster-based.
Converting a vector-based image to a pixel-based image is called rasterization.

19. Ray tracing
A type of global illumination rendering algorithm that excels at reflections and refractions.
Ray tracing realistically depicts scenes by calculating rays of light entering the virtual camera lens.
It works by drawing a ray from each pixel of the rendered image backwards into the scene until it intersects with a surface.

20. If the surface is reflective or refractive, additional rays are generated, bouncing off of the surface until they intersect with other surfaces, possibly generating additional rays.
This method is also used to generate ray traced shadows.
If a secondary ray bouncing off of a surface has a clear line of sight to a light in the scene, then that light contributes to the color of the surface at the point of intersection.

21. Reflection map
A simpler method of rendering reflective surfaces than the computationally expensive ray tracing technique.
An image is mapped onto a reflective surface.
As the object moves, the reflection map maintains its orientation to the world coordinate system, giving the illusion of a scene reflected in the object.

22. Refraction
Bending of light rays passing from one medium (e.g. air) into another (e.g. glass).
Can be simulating using refraction mapping (similar to reflection mapping), or through ray tracing.

23. Rendering
In computer graphics, the process of producing 2D images from a 3D scene.
During rendering, the computer "draws" the 3D objects to the screen and/or to a file, usually a bitmap.
Realtime rendering occurs when viewing objects in interactive viewports, or in games or simulations.
Non-realtime production rendering draws a much higher quality image, at the expense of speed.
A production render may take anywhere from a few seconds per frame to an indefinite period of time... sometimes hours or even days for a single frame.

24. Rigging
The process of setting up interactive controls for 3D characters or complex mechanisms.
Rigging is a technical process.
It is sometimes called character setup.
A good character rig makes it easy for an animator to focus on creative expression (acting).

25. Shading algorithm
A high-level rendering algorithm to represent how a surface responds to light.
A piece of computer code that is part of a material definition.
For example, the Blinn shading algorithm generically describes how highlights appear on surfaces.

26. Smoothing
A rendering algorithm to give the illusion of smoothness on polygon mesh surfaces.
Without smoothing, all polygonal objects would have a faceted appearance.
Also known as edge smoothing or face smoothing.
Smoothing can be accomplished through the rotation of vertex normals.

27. Specular The color of the highlight on a shiny object.
The color of a specular highlight is often determined more by the color of the light than by the object’s color.

28. Spline
In computer graphics, a spline is a line whose curvature is determined by control vertices.
Originally, a thin wood or metal strip used in construction.

29. Subdivision surface Algorithm that adds density to polygon meshes.
It can be used as a modeling tool, or invoked during rendering.
Low density mesh objects are smoothed through tessellation and smoothing of angles among adjacent faces.

30. Supersampling
An antialiasing algorithm that internally renders at high resolution, then averages pixel values for a lower resolution output.
Significantly reduces aliasing on some textures at the expense of longer render times.
Also known as oversampling.

31. Surface of revolution
A modeling technique to create rotationally symmetrical 3D objects by revolving a spline around an axis.
Commonly employed to create objects such as bottles and lathed furniture pieces.

32. Tessellation
The division of a surface into smaller polygons, yielding a higher level of detail.

33. Texture map
A bitmap or procedural map to vary some property, usually diffuse color, across a surface.
The term texture map, in the strictest sense, means the diffuse color map.

34. Transform The mathematical reassignment of points to new locations.
It's the abbreviated form of transformation. 
The three transforms are position (aka translation), rotation, and scale.
These transforms control the location and orientation of objects in 3D space.

35. Vector
In computer graphics, a vector is a curve or line in 2D or 3D space.
In mathematics, a vector is a straight line with a length and an orientation.
A vector may be defined by any two points in space.
It is also commonly defined by a single point, an angle (two angles required for 3D vectors), and a distance.
In Maya's MEL scripting language, vector refers to a group of three numbers, such as the X, Y, and Z positions of a point.

36. Vector graphics
Method for calculating or displaying data based on lines and curves rather than pixels or voxels.
3D models, 2D illustration paths, and digital typefaces are all examples of vector graphics.
3D models are constructed in vector space and usually projected into pixel space for display.

37. Vertex Plural: vertices. A fancy word for “point.”
Points are merely markers in space; they have no dimension whatsoever – no length, no area, no volume.
Vertices serve many functions in 3D graphics, from defining the contours of objects to anchoring parts of a hierarchy together.

38. Vertex normal
Lines pointing out from each vertex of a surface, important for lighting and edge smoothing.
The orientation of vertex normals determines how much light the surrounding surface can receive.
A vertex generally has several normals, one for each face shared by the vertex.
If all normals on a vertex are aligned, the renderer draws gradients across the connected edges.
If normals on a vertex are pointing in different directions, the renderer does not smooth the edges, resulting in a faceted appearance.

39. Voxel Contraction of volume element. Compare to pixel.
A voxel is a cubic section of a volume, used for calculating certain volumetric effects such as fluid dynamics.

40. Z-buffer
An automated method for managing depth information in a 3D scene.
Optimizes rendering by selecting which surfaces to render, and in what order.
The z-buffer ensures that occluded (hidden) surfaces are not rendered, saving time.

41. Z-buffer or depth buffer information can be stored within certain bitmap file formats such as .RLA and .EXR.
The z channel records the distance of each pixel to the camera.
This information is useful in compositing.
Simulated lens effects, such as distance blur from depth of field, can be added and adjusted after the 3D images have been rendered.

42. THANKS…