1. Computer Graphics Lecture 02 Graphics Systems Taqdees A. Siddiqi taqdees@vu.edu.pk

2. With the massive development in the field of computer graphics a broad range of graphics hardware and software systems are available. With personal computers… usage of variety of interactive input devices and graphics software packages Higher-quality applications… usage of special-purpose graphics hardware systems and technologies Introduction to Graphics Systems

3.  VIDEO DISPLAY DEVICES  RASTER-SCAN SYSTEMS  RANDOM-SCAN SYSTEMS  GRAPHICS MONITORS AND WORKSTATIONS  INPUT DEVICES  HARD-COPY DEVICES  GRAPHICS SOFTWARE Graphics Systems

4.  Refresh Cathode-Ray Tubes  Raster-Scan Displays  Random-Scan Displays  Color CRT Monitors  Direct-View Storage Tubes  Flat-Panel Displays  Three-Dimensional Viewing Devices Video Display Devices

5. Refresh Cathode-Ray Tubes Refresh CRT  Control Grid  Focusing System  Focusing in High Precision System  Construction of Cathode-Ray Tubes  Persistence  Resolution  Aspect Ratio

6. Refresh Cathode-Ray Tubes

9. Refresh Cathode-Ray Tubes Cont..

10. Refresh Cathode-Ray Tubes Refresh CRT  Control Grid  Focusing System  Focusing in High Precision System  Construction of Cathode-Ray Tubes  Persistence  Resolution  Aspect Ratio

11. Refresh Cathode-Ray Tubes

12. Raster-Scan Displays  Refresh Buffer or Frame Buffer  Pixel  Bitmap vs. Pixmap  Horizontal Retrace & Vertical Retrace  Interlaced vs. Non-interlaced Display

13. Random-Scan Displays  Vector Display  Refresh Display File  Random-Scan vs. Raster-Scan

14. Color CRT Monitors  Beam Penetration Method  Shadow Mask Method

15. CRT Displays Advantages  Fast response (high resolution possible)  Full colour (large modulation depth of E- beam)  Saturated and natural colours  Inexpensive, matured technology  Wide angle, high contrast and brightness Disadvantages  Large and heavy (typ. 70x70 cm, 15 kg)  High power consumption (typ. 140W)  Harmful DC and AC electric and magnetic fields  Flickering at 50-80 Hz (no memory effect)  Geometrical errors at edges

16. Direct View Storage Devices  Primary Gun  Flood Gun  Advantages & Disadvantages

17. Flat-Panel Displays  Properties Volume, Weight, Power  Emissive Display Plasma Panels  Non-Emissive Display Liquid Crystal Display

18. Plasma-panel Displays  Similar in principle to fluorescent light tubes  Small gas-filled capsules are excited by electric field, emits UV light  UV excites phosphor  Phosphor relaxes, emits some other color

19. Plasma-panel Displays  Two glass plates separated by neon gas  Vertical and horizontal conductors  Very rugged  No refreshing  Screens can be transparent and overlay documents  Used to be available in monochrome (Orange)  Now available in colour

20. Plasma-panel Displays  Advantages –Large viewing angle –Good for large-format displays –Fairly bright  Disadvantages –Expensive –Large pixels (~1 mm versus ~0.2 mm) –Phosphors gradually deplete –Less bright than CRTs, using more power

21. Liquid Crystal Displays  Liquid Crystal Display  A transmissive technology  Works by letting varying amounts of a fixed-intensity white backlight through an active filter  Organic crystals that align themselves together  When external force is applied they realign themselves  This is used to change polarisation and filter light

22. Liquid Crystal Displays

23.  Transmissive & reflective LCDs: – LCDs act as light valves, not light emitters, and thus rely on an external light source. – Laptop screen: backlit, transmissive display – Palm Pilot/Game Boy: reflective display

24. Advantages  Small footprint (approx 1/6 of CRT)  Light weight (typ. 1/5 of CRT)  Low power consumption (typ. 1/4 of CRT)  Completely flat screen - no geometrical errors  Crisp pictures - digital and uniform colours  No electromagnetic emission  Fully digital signal processing possible  Large screens (>20 inch) on desktops Liquid Crystal Displays

25. Disadvantages  High price (presently 3x CRT)  Poor viewing angle (type. +/- 50 degrees)  Low contrast and luminance (type. 1:100)  Low luminance (Natural light) (type. 200 cd/m2) Liquid Crystal Displays

26. Three-Dimensional Viewing Devices  Vibrating flexible mirror  Stereoscopic and virtual -reality systems -shutter glasses (with tracking) -headset with tracking -other VR devices  Holograms  NC-mills + soft material  Stereo-lithographic apparatus (SLA)

27. Virtual reality = stimulation of the human senses to simulate a fictive environment eyes: private eye, head mounted displays (hmd) ears: headphones, loudspeakers in hmd tactile sense: data glove, data suit, treadmill Virtual Reality Devices

28. 2 small screens display images for both eyes: high immersion degree head movement controls virtual camera artificial image only low resolution (e.g. 256 x 210) very expensive narrow view-angle Head Mounted Display

29. ultrasound tracking device used with stereoscopic glasses to track head position Light Weight HMD

30. Interactive Walkthrough

31. Data Glove

32. Computer Graphics Lecture 02 Graphics Systems Taqdees A. Siddiqi taqdees@vu.edu.pk