Keeping Up Appearances

1
Keeping Up Appearances

• With VRML

2
The Plan
Shape
Appear- ance
Geometry

• Material
• Lighting
• Textures

Material
Texture
Texture Trans.
Fridays Lecture
3
Material

• Ambient Intensity
• Diffuse color
• Emissive color
• Shininess
• Specular color
• Transparency

4
Ambient Intensity

• The ambientIntensity field specifies how much
  ambient light from light sources this surface
  shall reflect. Ambient light is omnidirectional
  and depends only on the number of light sources,
  not their positions with respect to the surface.
  Ambient colour is calculated as ambientIntensity
  diffuseColor.

5
Diffuse Color

• The diffuseColor field reflects all VRML light
  sources depending on the angle of the surface
  with respect to the light source. The more
  directly the surface faces the light, the more
  diffuse light reflects.

6
Emissive Color

• The emissiveColor field models "glowing" objects.
  This can be useful for displaying pre-lit models
  (where the light energy of the room is computed
  explicitly), or for displaying scientific data.

7
Specular color and shininess

• The specularColor and shininess fields determine
  the specular highlights (e.g., the shiny spots on
  an apple). When the angle from the light to the
  surface is close to the angle from the surface to
  the viewer, the specularColor is added to the
  diffuse and ambient colour calculations. Lower
  shininess values produce soft glows, while higher
  values result in sharper, smaller highlights.

8
Transparency

• The transparency field specifies how "clear" an
  object is, with 1.0 being completely transparent,
  and 0.0 completely opaque.

9
Lights

• Properties
• Intensity brightness of the direct emission
• Color
• Ambient Intensity intensity of the ambient
  emission
• Types
• Directional Light
• Point Light
• Spot Light

10
Directional Light

• DirectionalLight
• exposedField SFFloat ambientIntensity 0
  0,1
• exposedField SFColor color 1 1 1
  0,1
• exposedField SFVec3f direction 0 0 -1
  (-,)
• exposedField SFFloat intensity 1
  0,1
• exposedField SFBool on TRUE
• Does not attenuate

11
Point Light

• PointLight
• exposedField SFFloat ambientIntensity 0
  0,1
• exposedField SFVec3f attenuation 1 0 0
  0,)
• exposedField SFColor color 1 1 1
  0,1
• exposedField SFFloat intensity 1
  0,1
• exposedField SFVec3f location 0 0 0
  (-,)
• exposedField SFBool on TRUE
• exposedField SFFloat radius 100
  0,)
• Attenuation terms are 1/(a0 a1r a2r2)
• Range is absolute range

12
Spot Light

• SpotLight
• exposedField SFFloat ambientIntensity 0
  0,1
• exposedField SFVec3f attenuation 1 0 0
  0,)
• exposedField SFFloat beamWidth 1.570796
  (0,/2
• exposedField SFColor color 1 1 1
  0,1
• exposedField SFFloat cutOffAngle 0.785398
  (0,/2
• exposedField SFVec3f direction 0 0 -1
  (-,)
• exposedField SFFloat intensity 1
  0,1
• exposedField SFVec3f location 0 0 0
  (-,)
• exposedField SFBool on TRUE
• exposedField SFFloat radius 100
  0,)

13
Spot Light Details

• Radiates a solid angle from a given position and
  direction in local coordinates.
• angle the angle between the Spotlight's
  direction vector
• and the vector from the Spotlight
  location to the point
• to be illuminated
• if (angle gt cutOffAngle)
• multiplier 0
• else if (angle lt beamWidth)
• multiplier 1
• else
• multiplier (angle - cutOffAngle) /
  (beamWidth - cutOffAngle)
• intensity(angle) SpotLight.intensity
  multiplier

14
Spot Light 3
15
Textures

• Texture types
• Image Texture
• Movie Texture
• Pixel Texture
• Applications
• Intensity textures (one-component)
• Intensity plus alpha opacity textures
  (two-component)
• Full RGB textures (three-component)
• Full RGB plus alpha opacity textures
  (four-component)
• alpha opacity vrs transparency (where alpha 1 -
  transparency).

16
Image Texture

• ImageTexture
• exposedField MFString url
• field SFBool repeatS TRUE
• field SFBool repeatT TRUE
• 2D coordinate system (s, t) that ranges from
  0.0, 1.0 in both directions
• .PNG, .JPEG, (gif)

17
Pixel Image

• PixelTexture
• exposedField SFImage image 0 0 0
• field SFBool repeatS TRUE
• field SFBool repeatT TRUE

18
Texture Transform

• TextureTransform
• exposedField SFVec2f center 0 0 (-,)
• exposedField SFFloat rotation 0 (-,)
• exposedField SFVec2f scale 1 1 (-,)
• exposedField SFVec2f translation 0 0 (-,)

19
Mathematics of Light

• http//www.web3d.org/x3d/specifications/vrml/ISO_I
  EC_14772-All/part1/concepts.html4.14