IMM2202 Interactive Multimedia Development 3 3D animation...digital audio...digital video

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MUL242 3d modelling animation
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Surfacing
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this lecture...

• This lecture will look at
• surfaces and surface mapping
• surface properties
• surface maps
• mapping textures to surfaces

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textures

• three dimensional computer modelling is not only
  about geometry...the properties of object
  surfaces and how those surfaces interact with
  light and each other is of vital importance
• this is not trivial...it is as complex as the
  geometry modelling process
• rather than relying on explicit geometry to
  generate a detailed surface, 3D modellers use
  surface maps to define the appearance when
  rendered.
• a good surface map is worth a thousand
  polygons

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surface textures

• surface textures are composed by setting a number
  of properties which determine the nature of the
  rendered surface...
• surface colours allow you to pick the global
  colour properties of the surface and the
  reflections that may come from the surface
• surface properties are the principle settings
  that specify the overall appearance of a surface
• surface properties determine how a surface will
  respond to or reflect light shining on the
  object
• surface maps work in conjunction with surface
  properties and surface colours to provide a
  pixel by pixel control over the surface of an
  object - TEXTURES

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image maps

• rendering objects with textures using only the
  surface colours produces nice, smooth, uniform
  surfaces...makes them look computer generated
• surface maps are (usually) greyscale images which
  define the variation in levels of the surface
  properties across an objects surface.
• they vary the application of surface properties
  across the surface and hence make the texture
  more realistic
• there are a number of different maps which you
  can define...
• bump, diffuse, specular, glossiness,
  reflectivity, glow, opacity

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procedural textures

• procedural textures are defined mathematically to
  simulate (often using fractal-based technologies)
  natural or repetitive surfaces
• procedural textures simulate solid objects
  where the mapping of the surface to the object
  appears more natural
• lightwave supports
• repetitive checkerboard, grid, dots, bump array
  etc
• natural marble, wood, underwater, fractal noise,
  crust, veins etc

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bump maps

• bump maps simulate surface textures using
  greyscale images as a map to indicate highs and
  lows on the surface.
• white areas on the map are highs, black areas are
  lows, the transitional greys are slopes
  determining the depth of the depression
• b/w with no transition does not work

white
greyscale bump map
black
surface with normals
rendered surface
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bump mapping
colour
bump map
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bump mapping

• bump maps are usually combined with diffuse color
  maps to provide the colours of a surface
  texture...

bump
both maps
diffuse color
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Diffuse maps

• diffuse maps
• control how much diffuse light is reflected from
  an objects surface,based upon the pattern in the
  map.
• black in non-reflective, white is fully
  reflective...using the diffuse fraction as the
  upper limit

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Diffuse - ambient maps
original surface
diffuse map
the effect of both
ambient map
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other maps

• specular maps
• controls how much specular light is reflected
  from an objects surface,based upon the pattern
  in the map.
• black in non-reflective, white is fully
  reflective...using the diffuse fraction as the
  upper limit
• the interaction of specular and diffuse maps
  provides important visual cues about and objects
  composition and can simulate surfaces from metals
  to plastics, glass and paint

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other maps

• glossiness maps
• controls the position and amount of specular on a
  surface, based upon the pattern in the map
• black in non glossy, white is maximum
  glossy...using the glossiness factor as the upper
  limit
• reflectivity maps
• controls the level of reflectivity across a
  surface, based upon the pattern in the map
• black in no reflection, white is maximum
  reflection...using the reflectivity as the upper
  limit
• Gradient Maps
• Controls the application of a surface type via a
  gradient.

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other maps

• clip maps
• allows you to define areas on your surface that
  are transparent, based upon the pattern in the
  map
• black in opaque, white is transparent...using the
  opacity as the upper limit

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Gradients

• Gradients allow mapping based on geometry
• Gradients allow the use of precise placement of
  procedurals

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surface texturing

• therefore...
• surface properties determine the way a surface
  reacts to light and appears
• surface maps provide the means to modify the
  location and strength of these properties across
  a surface using the properties as the upper limit.

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How would you make this?
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the eggshell
ambient map (98) diffuse map (98) specular
map (25) opacity map (100)
render the image
start with a distorted sphere
apply a texture map
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mapping a surface to an object

• surface textures can be mapped onto objects in a
  number of ways...

planar
cylindrical
decal
cylindrical caps
cubic
spherical
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texture axis

• the texture axis defines the axis upon which the
  mapping operates
• planar - the face onto which the surface will be
  applied (a decal)
• Cylindrical / spherical - the axis about which
  the surface is wrapped

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planar
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cylindrical
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spherical
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cubic
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UV mapping
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Workshop

• Surfacing