particle systems and special effects

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particle systems and special effects
MUL242 Multimedia Design II
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why particle systems?

• many phenomena from the real world cannot be
  easily modelled as surfaces because the elements
  that make them up are ephemeral
• smoke, gas, steam, water, fire, clouds
• the surfaces in these phenomena are really
  molecule sized particles, which are so small and
  numerous that modelling them as geometry is
  impractical
• particle systems handle these types of phenomena
  by defining a number of particles which exist
  and move in 3D space
• the properties of the particles are numerous and
  must be defined in order to achieve the required
  effects

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particle system parameters

• particle system parameters are variable from
  system to system, some are vary complex, others
  quite simple
• lightwave comes with a simple particle system,
  Particle FX, built in.

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particle system parameters

• the essential parameters of a particle system
  include
• number of particles
• emission rate - the rate at which particles are
  emmited from the system (particles/sec)
• speed of particles - allowed to specify a minimum
  and maximum speed of emission so all particles
  are not going at the same speed
• lifetime of particles - how long the particles
  will live for
• eg. sparkler has a short life, flames longer,
  smoke longest
• particle source/emitter - the source of the
  particles in space
• can be parented or targeted to follow an object

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particle system parameters

• emitter spread - defines how wide a spread the
  particles have on emission
• eg. sparkler is 360, flame is wide, gun barrel
  firing very narrow
• wind - can be used to define a wind direction and
  turbulence to affect the way motion of the
  particles
• color range - the range of colors that a particle
  takes on during its life span
• eg. fire is red then yellow then dark over its
  life span
• collision detection - particles can bounce off
  each other and other geometry in the scene
• gravity - particles can be affected by gravity
• eg. particles in a water fountain

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other uses of particle systems

• hair and fur modelling
• hair and fur are commonly modelled using
  particles which leave a trail behind them as they
  move
• flocking
• systems which simulate animals in a flocking
  pattern, eg. birds, fish, lemmings
• explosions
• systems which take an object and break it into
  its polygons and move each as if it were a
  particle in a particle system

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Particles in Lightwave

• 2 Main types of emitter
• HVE Emitter - No actual volume, simply points in
  space
• Partigon Emitter - outputs single point polygons
• Partigons can be used to create many effects (eg
  fireworks, sparks)
• Have surface, so surface properties can be
  altered
• Are quicker to render than HVE particles
• HVE Emitters simply create nulls
• Surfaces need to be added using Hypervoxels
• Take Longer to render
• Hypervoxels can still be applied to partigons to
  create more complex effects than simple points of
  light

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hypervoxels

• hypervoxels allow you to create organic globs
  around points, these globs interact with one
  another when they are close enough cf. metaballs
• hypervoxels have no real geometry (other than the
  point from which they are created)
• hypervoxels allow you to define 3d algorithmic
  textures which can be used to define objects
  which have irregular/natural surface variation
• Can be used to create effects such as running
  water, smoke steam etc.

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Other uses of hypervoxels
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How did they do that?

• Create a Null Object
• Add Hypervoxels to the Null Object
• Choose Volume as the Hypervoxel effect (more
  suited to fire than surface)
• Geometry
• particle size 2m
• Size variation 65
• Shading
• Color to RGB 250, 210, 120
• Luminosity 150 (creates inner glow)
• Opacity density 100, Thickness 80, smoothness
  30 to create fiery smoke look (dense centre
  softer outer edge)
• Create a gradient texture using local density as
  input parameter for both colour luminosity to
  create changes as explosion expands out

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How did they do that?

• Use Hypervoxesl Hypertexture tab to use a
  procedural texture to alter the surface over
  space (assists in billowing effect)
• Texture type turbulance
• Frequencies 0
• Contrast 0
• Small Power 0.5
• Texture amplitude 125
• Texture effect billowing
• Effect Speed 65
• Animating the explosion
• In Layout, select size and create 2 keyframes,
  one where the null is small, another where it is
  large (animates the explosion)
• Create an envelope for dissolve in the
  Hypervoxels panel. This brings up the graph
  editor and allows you set keyframes for the speed
  at which the explosion dissipates
• Adding a texture for dissolve allows you to use
  turbulence or other effects to make the dissolve
  less regular smooth

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How did they do that?

• Finally.. Add Camera Shake
• Select the Camera and enter the motion options
  (m)
• Add LW_Jolt plug-in
• Double click on the plug-in to change the
  parameters
• Create key at frame 0 (Jolt starts then)
• Duration 55
• Position XYZ 0.01,0.02,1.2
• Rotation HBP 0.1,0.2,1.2
• Fallof on
• Spring off

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Modelling Hair Fur

• Hair Fur can be generated using a plug-in
  called Sasquatch (Sasquatch Lite now integrated
  into Lightwave 3D)
• Allows the creation of realistic hair fur
  surfaces using particles

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Modelling Hair Fur

• Hair Fur can be generated using a plug-in
  called Sasquatch (Sasquatch Lite now integrated
  into Lightwave 3D)
• Allows the creation of realistic hair fur
  surfaces using particles

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SasLite Parameters

• Fiber Color
• Hue Bright Vary
• Adds randomness to fibre colour
• Diffuse, Specularity Glossiness
• how individual fibres react to light
• Courseness
• thickness of fibres
• Frizz
• makes the fibres wiggle more
• Fur Density Length
• how many fibres and their length in relation to
  the objects size
• Non-Linear ie doubling the amount more than
  doubles the effect
• Drooping
• Fibres bend downwards due to gravity
• Clumping
• Fibres gather toghter in groups
• Combing
• Hair fur have preferred angles

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Compositing

• 3D animation can be seamlessly combined with live
  footage
• Makes use of
• Background Foreground images
• Alpha Channels
• Compositing can be done in Lightwave or Video
  Editing Tool (eg Adobe After Effects)

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Combining Live Action 3D

• Walt Disneys Dinosaur

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Combining Live Action 3D

• Walt Disneys Dinosaur

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Combining Live Action 3D

• Walt Disneys Dinosaur

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Combining Live Action 3D

• Walt Disneys Dinosaur

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Combining Live Action 3D

• Walt Disneys Dinosaur

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Compositing in Lightwave

• Foreground Background images are loaded as
  Backdrops into Lightwave
• Images centre stretch to fill the screen,
  regardless of camera position and perspective
• Volumetrics (eg fog) do not affect Backdrops
• Individual surfaces (eg transparency) do not
  affect Backdrops unless this option is set in
  Surface Editor
• Alpha Channel acts as a mask or cut-out,
  allowing part of the image to be opaque, and part
  transparent
• Foreground Keys allow you to define colour ranges
  as a mask, (similar to blue screen effects in
  traditional TV compositing

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Start with a basic scene
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Load Foreground, Background Alpha
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Finished Result
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Intermediate Compositing

• Intermediate Objects (eg trees, buildings etc)
  are often required to allow your rendered objects
  to trace a path behind in front.
• Can be achieved using Front Projection image
  mapping onto flat polygonal surfaces
• Things to note
• Increase the Luminosity of the surface to prevent
  scene lights as only source of light (would look
  unnatural)
• Shadows can be applied by altering light
  positions, but
• Luminosity luminosity diffuseness need to be
  further adjusting to ensure the intermediate
  scene elements blend with foreground and
  background
• See Chapter 18 of Inside Lightwave for more info

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MUL242

• Hypervoxels
• Particles
• Compositing