WEEK 6: TEXTURE MAPPING

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WEEK 6 TEXTURE MAPPING
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Mapping Defined

• Mapping (or texture mapping)
• Process of developing and assigning material
  attributes to an object
• Enables user to give the object a specific
  colour, apply a pattern, adjust its shininess,
  etc

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• Material
• The encompassing term for all the different
  attribute settings that are assigned to an
  objects surface
• Might be identified by a name. Example. Shiny
  Red Plastic

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• Surface Attributes
• Refer to the basic material settings, such as
  colour, Shininess, Transparency, etc.
• Affect all all parts of an object equally

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• Texture
• Refers to a bitmapped image, either scanned or
  painted
• Sample textures might include a scan of a block
  of wood that captures its grain patterns, a
  painting of rusty metal, 2D logo, etc

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• Textures can be used to vary surface roughness,
  transparency, and colour of an object

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Light and Colour

• Three different colour sources
• 1. Ambient
• 2. Diffuse
• 3. Specular

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Surface Attributes

• The most basic type of material settings
• Most of these attributes are set with sliding
  controls or type-in boxes in the material editing
  section

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• Surface Attributes
• 1. Colour
• 2. Shininess
• 3. Specularity
• 4. Transparency
• 5. Falloff
• 6. Index of Refraction
• 7. Luminosity

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Colour

• Combination of three elements
• 1. Hue
• 2. Saturation
• 3. Value

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Shininess

• Overall reflective nature of the object
• A measure of an objects surface gloss
• Shininess has an effect on the size of the
  specular highlight

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Specularity

• Adjusts the intensity of the objects highlight
• Specular highlights are the bright reflections of
  light seen on glossy objects
• Specularity and Shininess work together to define
  objects glossiness Metallic and plastic
  materials

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Transparency (Opacity)

• Transparency and Opacity are opposite terms both
  used to control the amount of light that can pass
  through an object
• Example.
• Transparency 100 OR
• Opacity 0
• Object ? Is invisible

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• Example.
• Transparency 0 OR
• Opacity 100
• Object ? Is opaque

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Refraction

• Controls the degree to which light is bent when
  it passes through a translucent object ?
  simulates realistic bending of light when it
  passes through different materials

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• A setting of 1.0 means no refraction occurs
  higher numbers increase the amount of bending
• Is supported only in programs that do ray tracing

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Luminosity (Self Illumination)

• Adjusts how much an object appears to be lit from
  within
• As luminance is increased, it flattens out the
  effects of the ambient and diffuse light sources

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• 0 is completely unlit, while 100 is totally
  self-illuminated

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Map Channels

• Textures (maps) can be derived from scanned
  images, 2D paint work, mathematical processes,
  etc
• The surface attributes of the material that can
  accept an image are called map channels

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• Four basic categories
• 1. Diffuse
• 2. Bump
• 3. Reflection
• 4. Opacity

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Procedural Textures

• Procedural textures require no mapping
  coordinates less memory than bitmapped textures
• Procedural noise can be used ? to add realistic
  variation to any type of texture, or be applied
  as bump map

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Tiling

• A method of repeating one image over a large area
• Use less memory but some drawbacks look too
  uniform, tiles have a tendency to show seams or
  patterns because the images are all lined up in
  neat rows

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Face Mapping

• Causes the bitmap image to conform to each face
  of the object individually
• No mapping coordinates are required, but the
  bitmap may be deformed depending on the size and
  shape of the faces

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Mapping coordinates

• Are a set of coordinates that specify the
  location, orientation, and scale of any textures
  applied to an object

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• Image (XY) Coordinates
• Mapping (UVW) Coordinates
• Planar Coordinates
• Cylindrical Coordinates
• Spherical Coordinates
• Cubic Coordinates
• Wrap Coordinates