Computer Graphics Module Overview

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Computer GraphicsModule Overview

• CO2409 Computer Graphics
• Week 1, Part 1

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2D Graphics

• Pixels / Colours
• 2D Geometry
• Bitmaps / Sprites
• Pixel blending
• 3 weeks
• A gentle introduction
• Module will get harder!

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3D Maths - Intro

• 3D Geometry
• Maths Essentials
• Basic functions
• C Issues
• Numerical limitations
• Preparing for 3D work
• 1-2 weeks

4
3D Maths 3D Transformations

• Matrices
• General and 3D-specific
• 3D coordinate spaces
• Transforming between spaces
• Transforming to 2D
• Cameras
• 3 weeks Key topic

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Using Graphics APIs - DirectX

• Rendering Pipeline
• Input data / Materials
• Transformations
• Lighting
• Pixel Rendering
• Lectures cover theory
• Implement in DirectX
• 5 weeks

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Graphics APIs - OpenGL

• Brief comparison with DirectX
• Look at same aspects of pipeline
• Same principles as DirectX
• Covered very briefly

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Advanced Topics Shaders

• Vertex Pixel shaders used throughout
• Transformations
• Lighting
• Texturing
• Advanced Techniques
• Normal mapping
• Cell shading
• Reflection and Refraction
• Several weeks

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Advanced Topics Shadows/Mirrors

• Depth / Stencil buffers
• Stencil Shadows
• Shadow Maps
• Reflection
• 2 weeks

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Advanced Topics Animation

• Matrix Hierarchies
• Rigid body animation
• Soft body animation
• Skeletons and Skinning
• 2 weeks

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Plus

• Graphics Hardware
• Review / revision sessions
• 3 weeks
• 1 Assignment
• 2 hour written exam

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Computer GraphicsPixels Colours

• CO2409 Computer Graphics
• Week 1, Part 2

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Todays Lecture

• Pixels
• RGB colours
• HLS colours
• Other colour spaces

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2D Graphics Pixels

• A computer display is a grid of small rectangular
  areas called pixels
• Each pixel can display a range of colours
• Usually created by blending red, green and blue
  light
• Wont consider hardware mechanisms for this
• All modern computer graphics are simply arrays of
  coloured rectangles

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2D Graphics Pixel examples
Pixels are made from red, green, and blue
components All images are made from pixels
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RGB Colours

• One way to define a colour is to specify the Red,
  Green and Blue components
• Typically 3 integers in the range 0 to 255 (from
  no colour to maximum intensity)
• E.g. Bright red R255, G0, B0
• Or can use floating point values from 0.0 to 1.0
• E.g. Bright green R 0.0, G 1.0, B 0.0
• The colours blend in the same way as light
• Blending maximum R, G B gives a white colour
• No R, G and B gives black (no light)
• Another example RG Yellow

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RGB as a Colour Space

• Can draw a picture/graph of the RGB colour space
• All available colours are mapped to a cube, with
  axes R, G and B
• Simple to implement
• Integer RGB often packed into one hexadecimal
  value
• E.g Bright red 0xff0000

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The HSL Colour Space

• Artists often use the HSL (or HLS) colour space
• H Hue (the base colour from the spectrum)
• S Saturation (the richness of the colour)
• L Lightness (the brightness of the colour)
• Maps the colours to two cones
• Theses values can be more intuitive than RGB

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Other Colour Spaces

• HSV / HSB (Hue, Saturation and Value/Brightness)
  is closely related to HSL
• CMYK (Cyan, Magenta, Yellow and Black) is used
  for printing and blends colours in the same way
  as ink
• Lab colour is the a very precise colour model,
  designed to accurately reflect the response of
  the eye to colour
• YUV and YIQ are colour spaces used for broadcast
  television
• You may see some of these in graphics apps