WEEK 10: RENDERING

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WEEK 10 RENDERING
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Resolution

• Refers to the number of horizontal and vertical
  pixels in an image
• Defined by a set of two numbers, such as 640 x
  480 (640 pixels wide 480 pixels high)

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• Aspect ratio ? the relationship between the width
  height of the image
• Example. In 640 x 480, the aspect ratio 1.33 1
  (or 43) common for TV and computer monitors

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Colour Depth

• How many colours each pixel is capable of
  displaying
• Usually expressed in terms how many bits an image
  contains

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• Example. In 8-bit image (.gif file), each pixel
  is represented by 8-bits, allows the pixel to be
  any one of 256 different colours

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Alpha channel

• An optional layer of image provides and
  additional 8 bits of information about
  transparency
• Is simply tacked onto RGB data, so 24-bit image
  with alpha channel becomes a 32-bit image

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• Is capable of 256 levels of intensity
• See Figure 10.1 Alpha channel functions as a
  mask or matte allowing portions of an image to
  be seen, the rest is replaced with background
  image

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• Allows for transparency effects ? multiple images
  with alpha channels can be composited together
  into a single image

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Anti-aliasing

• A method of reducing jagginess by filling in
  pixels at the stairstepping points with colours
  that are midway between the line colour and the
  background colour
• Soften the stairstepping, look smoother

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Atmosphere

• Adding atmosphere settings, creating the effect
  of objects being seen from great
  distances/through a mist
• Fog ? common atmospheric effect a mist effect
  its defined with set of ranges that delineate
  where the effect begins and ends (min and max
  concentration)

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Post-Production Effects

• Some 3D products offer built-in post production
  effects, which include transitions, colour
  manipulation, etc
• Built-in post-production effects
• 1. Lens flares
• 2. Glows
• 3. Motion blur

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Lens Flare

• Pattern of bright circles and rays, is seen when
  you point a camera lens toward the sun/bright
  light source
• Lens flares ? add realism to scene with bright
  light to create the illusion that real camera was
  used for the shot

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Glows

• To increase realism
• Commonly needed for 3D graphics
• Glows are usually assigned to objects, a
  particular colour in the scene, or a material

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Motion Blur

• The smearing that occurs in an image when the
  subject or camera is in motion
• A natural occurrence, an animation look
  unnaturally sharp if this effect isnt present

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• Also works in still images to convey a sense of
  movement and speed

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Post-processing with 2D Programs

• Photoshop, Premiere, After Effects, etc are 2D
  programs that can deal with sequential images ?
  can be used to create certain post-production
  effects