Lecture
2 - Computer Hardware and Software |
Cathode Ray Tube (CRT)
Vector Display
Random Scan display
Calligraphic Refresh Display
Direct-view Storage Tube Display
Raster Display
CLUT
Flat Panel Displays
Emissive:
Plasma
Each pixel made of three cells containing xenon and neon gas
Horizontal and vertical electrodes create unique grid to locate cell positions
Gas in each cell is ionized when a voltage difference is applied to intersecting electrodes
The current creates a rapid flow of charged particles, which stimulates the gas atoms to release photons of ultraviolet light
Photons excite the phosphor coated on the inside wall of the cell.
(Pictures from: "How Plasma Displays Work")
Non-emissive:
LCDs\
Organic molecules that align themselves in crystalline structures in the absence of external forces
Application of external force rearranges them as if they were a liquid
Liquid
crystals respond to heat or electromagnetic forces
LCDs used as optical modulators
Change polarization
In unexcited or crystalline state, LCDs rotate the polarization of light by 90 degrees.
In the presence of an electric field, LCDs behave like a liquid and align their electrostatic charges with E field.
Definition - VR is a computer generated, interactive, three-dimensional environment in which a person is immersed.
HMD - head mounted display
Cave based VR
1992/93 - EVL's
Cave (http://www.evl.uic.edu/home.html
)
Cruz-Neira, Sandin, DeFanti, Kenyon and Hart
Electronic Visualization Lab -
Trimension
Cabin - Fully enclosed cave
SkyVision Full-Dome (SkySkan.com)
Imax
Elumens Visionstation (VS) - Hemispherical Display
Elumens Visionstation (VS3)
Elumens Visionstation (VS3)
Depth: 8'-10" (106")
Height: 7'-9" (93")
Width: 11'-4" (136")
Panoramic - Curved Walls
Trimension (others - Barco)
MultiWalls
Three Wall - CAEV -
Tables, Desks, Single Screens
Immersadesk 2 - EVL
Fakespace
Trimension
The Grip Project - UNC
The NanoManipulator - UNC Chapel
Hill
http://www.cs.unc.edu/Research/nano/
Movie
Responsive Workbench - 1993
Cubby -
Mount Fuji Stereo Pairs
Free Viewing
Cross Eyed Viewing
Left Eye
Right eye
Left Eye
5DT HMD 800
Display Resolution: 800x600x3(rgb)
pixels - Full SVGA
Optics Field of View: 28 (H)
x 21 (V) degrees
Headphones:
Type: Sennheiser HD 25 closed
dynamic headphones
Frequency Responce: 16Hz -
22Hz (3dB)
Autostereographic Display
MultiMo3D , Heinrich-Hertz-Institut für Nachrichtentechnik,
Principles and prototype of a 50-inch projection-type dual lenticular screen
3D display.
Volumetric Display - Actuality Systems
Image Size and Display Type
- Approx.
10" diameter spherical image
- Swept-screen multiplanar volumetric display
- Autostereoscopic: no viewing goggles
- Volume-filling imagery
- Supports many simultaneous viewers – no
head-tracking
Tracker - Head
position and Orientation
- Determines viewpoint of
virtual world
Datagloves - Hand position and orientation
- Monitors
status of user's fingers
Image Scanners
Printers (Raster)
Laser
Inkjet
Plotters (Vector)
3D Printing
Stereolithography (from howstuffworks.com )
Create a 3-D model of object
Software slices model into thin layers -- typically five to 10 layers/millimeter
The 3-D printer's laser "paints" one of the layers, exposing the liquid plastic in the tank and hardening it
The platform drops down into the tank a fraction of a millimeter and the laser paints the next layer
This process repeats, layer by layer, until your model is complete
Ink-jet Printing – (e.g. Z-Corp )
Languages -> Commands -> APIs
Coordinate Systems
Local Coordinates
World Coordinates
Device
Coordinates
Transformations
Model
-> World -> Normalized -> Device
Graphics
Functions
General
purpose graphics packages provide:
Functions
– I/O, attributes, transformations, viewing
Output
primitives – building blocks of images
Attributes
– properties of images
Geometric
transforms
Viewing
transforms
Software
Standards:
GKS
Phigs
OpenGL – http://www.opengl.org/
Web3D – www.web3d.org