# CGT 101 Test 1 Review

## Terms

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- CAT (scan) stands for...?
- Computer Aided Tomography
- CADAM stands for...?
- Computer Aided Design System and Manufacturing System
- CADAM was created by...?
- Lockheed, with IBM
- Allowed US Air Force to use command and control point and click CRT displays to detect and track aircraft
- SAGE Air Defense System
- First personal microcomputers
- Apple II, Timex Sinclair, IBM-PC
- Mass Market Personal Computers
- Intel microprocessors, Apple Macintosh, IBM personal computers
- Microsoft's standardized disk operating systems for mass market personal computers
- DOS Operating System
- Commercial CG Application Software
- Autodesk, Adobe, Alias, Wavefront
- PC Hardware Benchmarks in 1980s
- 50 Mhz clockspeed, 8-32 Mb RAM
- Algorithms developed in 50s and 60s
- early 3d - hidden surface removal, color, shading
- Algorithms developed in 70s
- Gouraud shading, Phong shading, texture mapping, bump mapping
- Algorithms developed in 80s
- Ray tracing
- PC Hardware Benchmarks in 1990s
- 400-500 Mhz clockspeed, 64-256 Mb RAM
- PC Hardware Benchmarks in Early 2000s
- 1000 Mhz clockspeed, 512 Mb - 1 Gb RAM
- PC Hardware Benchmarks in Mid 2000s
- 1000+ Mhz Clockspeed, 2+ Gb RAM
- The visible spectrum of light ranging from red to violet (red, orange, yellow, green, blue, indigo, violet) defines the range of the normal human visual system to perceive color.
- Color as a Function of Light
- This is the apparent color, irrespective of brightness or saturation. Ex: Red, green, blue, and yellow
- Hue
- This is the level of purity in a single color's hue. AKA Chroma in video graphics
- Saturation
- This is the relative lightness or darkness of a color. A high ___ range in an image is said to have high contrast and generally gives a richer and more detailed look than one with a low ___ range.
- Value AKA Brightness
- The number of indivisual colors a file format can display for each pixel.
- Color Depth
- 8-bit color has this many varieties
- 256
- 16-bit color has this many varieties
- 65,536
- 24-color has this many varieties
- 16,777,216
- Number of varieties in grayscale
- 256
- RGB color model is a _____ color model; produces white
- Additive (color model)
- CRT (displays) stands for...?
- Cathode Ray Tube
- This is a color range - the total number of colors that can be faithfully reproduced in a given format such as websafe colors, CYMK printable colors, NTSC, or film. (Warning icons in photoshop = triangle for print and cube for web)
- Gamut
- ____ Color Model; CYM (cyan, yellow, and magenta) mixture created from RGB primaries; commonly used for generating color output for print and hard copy media
- Subtractive (color model)
- Blue + Green levels =
- Cyan
- Red + Blue levels =
- Magenta
- Red + Green levels =
- Yellow
- Term used to describe the appearance of a light source, measured in degrees Kelvin.
- Color temperature
- Color temperature around 8,000 K
- Cool/Blue
- Color temperature around 1,500-2,000 K.
- Red/Warm
- Simplest form of computer-generated object, consisting of a line formed by two points. Three points connected by lines form a polygon. Are generated from underlying math formulas for lines and other geometric entities. AKA Object-based graphics
- Vector Graphics
- Graphic images made up of rows of dots or pixels as opposed to vector line representation. AKA image or bitmapped graphics
- Rastor Graphics
- 2D array of pixels used to store an image. Also referred to a rastor graphics as opposed to vector graphics. Stricly speaking, this has only one single bit of color info per pixel, therefore it is either black or white
- Bitmap
- A raster image file with more than 8 bytes per pixel. Usually referred to when more than 1 bit is used per pixel.
- Pixmap
- An attempt to approximate a higher number of colors in a lower bit-depth color system or a lower resolution image. Done by assigning two similar colors that are able to be reproduced to adjacent pixels. The results produce the illusion of smoother edges
- Dither
- The horizontal rows of pixels that make up a raster image.
- Scan lines
- NTSC (National Television Standards Committee, 1953) broadcast signals provided _____ viewable scanlines.
- 480
- Digitally created imagery with enough resolution for mtion pictures requires about _____ scanlines.
- 2000
- An object-based curve (vector graphic) defined by a math function. Ex: Bezier Curve, NURBS
- Spline
- Another name for a line segment. This should not be confused with a vector or a 3D geometric primitive.
- Vector Primitive
- In software programs, the _____ is the rectangular area formed by the crawling dotted line denoting the selected part of an image.
- Marquee
- End-to-end vector primitives connected at their endpoints make a _____.
- Polyline
- The "world space" or fixed Cartesian coordinate system which defines the entire 2D or 3D coordinate space.
- World/Global Coordinates
- The individual coordinate system for each point, line, curve, object, group, or other subset of objects that exist within world/global coordinate system. Making changes to _____ coordinate systems affect only the objects associated with that coordinate s
- Local/Relative Coordinates
- A singular but continuous set of connected vector primitive line segments (or curves) connected by their endpoints (vertices). To make them more useful in applied graphics, the individual segments and vertices can be moved or have their curvature edited.
- Polyline
- A _____ is a closed-loop polyline composed of at least 3 vertices and 3 edges. The basic elements for defining surfaces in a _____ mesh.
- Polygon
- A 4-point polygon is called a...?
- Quad
- Type of cubic polynomial curve first described by Pierre Bezier in 1970. It is defined by two end points and a scaleable tangent vector which can be used to control the shape of the curve. A common and dominant method for creating and editing vector grap
- Bezier curve
- Basic geometric modeling forms are building into all standard 3D software packages. Typical 3D ______ include cubes, cylinders, spheres, and cones.
- Geometric primitive
- 3D models and diplays contain only point and edge information about the polygons which make up the model. Surface data is either not present in the display or does not exist for the model. Are fast and easy to display and are useful for viewing and editi
- Wireframe
- Composed of polygonal surfaces and enclosing spline curves or polyline cross sections/profiles or they may be NURBS based. Are designed to contain and display only visual information about the surface properties and characteristic shape of a 3D object. D
- Surface modeling
- Common method of modeling used in computer aided design. Used to generate whole objects with solid mass properties, not just surfaces, by means of solid primitives, extruded shapes, revolved shapes, Boolean operations, and other sweeping operations.
- Constructive Solid Geometry (CSG)
- NURBS stands for...?
- Non-Uniform Rational B-Spline
- An advanced class of spline based modeling which allows end users an almost unlimited control of the shape of both curves and surface contours through weighted control vertices.
- NURBS
- Basic geometric modeling forms are built into all standard 3D software packages. Typical _____ include cubes, cylinders, spheres, and cones.
- 3D Geometric Primitives
- A surface described by numerous connecting polygons.
- Polygon mesh
- The point at which an object may be rotated about in 3D space.
- Pivot Point
- Individual points which defined on a 2D curve or 3D surface which can be used to modify (transform) the shape of the curve or surface.
- Control vertices
- When both sides of a surface are made renderable and can be viewed regardless of their orientation to the camera.
- Double Sided
- To make a surface or 3D model by creating a cross section and extending or "sweeping" it along an axis which is typically perpendicular to the face of the cross section.
- Extrude
- A 3D model which is created by revolving or "sweeping" a crowss section or profile around an axis.
- Surface of Revolution
- The nested grouping of objects in a scene that defines dependencies of translation, rotation, and scale.
- Heirarchy
- An object node above another
- Parent
- An object node below another
- Child
- Useful method of modeling that combines 2D and 3D models based on the math logic of Union, Difference, and Intersection.
- Booleans
- Adding aka...?
- Union
- Subtracting aka...?
- Difference
- Common volume aka...?
- Intersection
- Process of subdividing and refining a polygon mesh into a series of smaller polygonal faces while maintaining the general shape of the original object. AKA splitting, dicing, or adaptive subdivision.
- Tessellation
- The creation of a 3D surface by interpolating contour between two or more splines.
- Skinning
- AKA "Blob" modeling; Refers to the implicit surface modeling technique developed and advanced by the Japanese company Links, Osaka University, and the artist Yoichiro
- Metaballs
- Making a virtual copy of an object; The new virtual model is a ghost of the original object that can be modified indirectly by editing the original object
- Instance
- An operation which alters the position, orientation, or proportional size of a 3D object in its coordinate space.
- Geometric Transformation
- The 3 principle geometric transformations in CG
- Translation, Rotation, Scaling
- The surface normal that faces away from the camera and is completely occluded by other polygons.
- Back-Face
- Process that removes a polygon's back-face from a scene to speed up rendering calculation.
- Back-face Culling
- Slang term for a free-form deformation matrix tool.
- Bendy Box
- A modeling technique which allows the user to create a more complex model by selectively deforming simpler primitive objects. This technique typically uses an attached control lattice to manipulate an underlying polygon mesh or NURBS model
- Free-form Deformation
- To change the shape of a 3D model's geometry through means OTHER than the basic modeling methods of primitive creation, extrusion, revolution, lofting, or skinning.
- Deformation
- Modeling technique used to actually distort the surface geometry during rendering by using 8-bit grayscale raster image map values; Developed by R. Cook in 1984.
- Displacement mapping
- A generic geometric modifier that transforms the positions of an object's vertices along any combination of 3 axis; Thi important modeling & animation tool simulates random variations in an object's shape.
- Noise