CD2012 Principles of Interactive Graphics

Lecture 04

Graphics Hardware

Abir Hussain

www.cms.livjm.ac.uk/cmsahus1

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Previous Lecture

• Transformation– Translation: glTranslated ( x, y, z) – Scaling: glScaled (x, y, z)– Rotation: glRotated (angle, x, y ,z)

• Combining transformations– glLocaIdentity()– glMartrixMode()

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Today’s lecture and lab

Plotters

Printers

LED and

LCD

Plasma Screen

CRT Hardcopy devices

Display devices

Interactive Input Devices

Graphics hardware

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Display Devices

Cathode Ray Tube (CRT)• A beam of electrons emitted by an electron gun, passes

through the focusing system.

• The light output of the phosphor decays rapidly– The display processor refreshes the phosphor around 60,70

times per second (60Hz, 70Hz)

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Other Display Technologies

• Liquid crystal display (LCD) – The picture is displayed through light emitted from crystal– Flat screen for desktop computer and screen for laptop

• Light emitting diodes (LED) – The picture is displayed through light emitted from diodes– Large screen for sporting events, concerts or commercial

advertising

• Plasma Panel display– Constructed from filling the areas between two glasses with neon

gas– For Home TV, very thin, light, expensive

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Other Display Technologies

Plasma panel displayCRT screen

LCD touch screen

LED large screen

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Other display technologies

• Head-Mounted displays

– Use prisms and/or lens to project an image from small LCD or CRT screen

– Provide an immerse experience by blocking out the real world

– Fairly easy to set up– Can achieve good stereo quality– Heavy and do not fit well

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Graphics output frame butter

 

 

• For CRT display, a scan controller converts information from the frame buffer and controls the scanning of electrons across the screen to draw the image– The scan controller draws pixels from left-to-right and

top-to-bottom across the display– The complete screen is re-drawn at a given refresh

rate e.g. 60Hz, 70Hz

• For LCD display, data can be taken directly from the frame buffer so scan controller is not needed.

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Modern PC graphics cards• Current PC graphics cards may have 16, 32 or

64Mbytes of video memory. • This memory can hold one or more screen

images plus textures. • Some graphics cards (e.g. GeForce2) may have

hardware for– Transform calculations– Lighting calculations– Moving areas of memory in the frame buffer– Applying textures

• These reduce load on the main system CPU

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Hard Copy Devices

• Printers Originally the printers were used to produce text

pages, however they are now widely accepted as graphical devices.

• Plotters They are devices, which produce hard-copy line

drawings. The most common type of plotters use ink pens for the generation of the drawing. In now days, many plotters use ink-jet sprays, laser beams and electrostatic methods.

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2D Input Technologies• Keyboard - All computers are equipped with keyboards.They send strings

of characters to the applications up on request• Mouse The mouse has been around since 1968 and has evolved into - One (Apple), Two (PC) and Three (UNIX) buttons - Ball or optical movement sensors - wired and wireless operation• The basic drawbacks of the mouse are as follows

- Controlled by the arm and wrist muscles - not fine control- Needs space to operate- Is a relative positioning device - which is useful in some

applications but not others

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2D input technologies

• Pen and graphics tablet-based devices - Allow fine detail control using finger muscles- Can (with tablet) allow absolute positioning- Useful in design and engineering applications

• Tracker balls and tracker pads- Take up less space and useful for mobile

applications- Can be difficult to control for small movements

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3D Input Technologies

• 3D input devices are less common as they are- more expensive- can be hard to learn to use- can be error prone and difficult to set up

• Position trackers - e.g. Polhemus fastrak- Usually operate by creating a magnetic field - Sensors mounted on head, hand or elsewhere record

movement in field- Can be distorted by metallic objects- Normally used for two purposes.

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3D input technologies

Cybergloves and cybersuits

– Contain sensors which measure the bend of body joints

– Used with position trackers to record the full range of movement

– Very expensive– May need to be calibrated for each

user– Can become less accurate with use

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3D input technologies

• Space ball - allows movement in 3 dimensions

The 3D Controller enable a whole new level of 3D interactive motion control. Can easily move or rotate 3D object by gently pushing, pulling

or twisting the Power Sensor ball. 

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Coursework 1

• Write a C++ program using OpenGL that presents a scene described in the coursework spec

• The scene will include a basic set of graphical components as specified below

• Plagiarised work will receive no marks. Plagiarism includes copying material from the Internet

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Coursework 1 guidelines

Cars park– Car park spaces for parking cars – A number of parked cars – A barrier on the entrance and the exit of the car park – A charging machine

      

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Coursework 1 guidelines

• Marks

1. Design document 30%2. C++ Code accuracy, layout and readability 20%3. C++ Code good use of OpenGL 20%4. Extra features 10%

interaction, animation, 3d effects5. Demonstration 20%

How well the program meets the coursework spec Are the objects recognisable ?

Are colours and shapes used appropriately?

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Coursework 1 guidelines

• Use the code in L:\CD2012 as a starting point (circles, transforms etc.)

• The design report should properly explain how you went about constructing the scene

• The display function should not be a long list of glVertex() calls

• Split the drawing of the scene into different functions

• Any questions - ask the module leader.

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Summary

• Display devices - CRT, LED, LCD, plasma panel display - Frame buffer/ Graphics cards• Hard copy devices - printers , plotters• Interactive input devices - 2D input Keyboard, mouse, tracker ball/pads, - 3D input Position trackers, cybergloves, cybersuits, space ball• Coursework1