State of the Art Commercial Systems

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State of the Art Commercial Systems

• JunHyeok Heo
• HyungSeok Kim
• Computer Sciene Dept. of KAIST

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Levels on Tools
VR Tools
3D Graphics API
Performer Inventor VRML Browser OGL Optimizer DX
3D RMode ...
Vega OpenGVS WTK SuperScape ...
GL/OpenGL DX 3D IMode ...
Glide DX 3D IMode ...
Application-specific processing
Pixel processing
Polygon processing
Scene processing
Special Effects Input Devices Network Sound Dynami
c Behaviors
Hidden pixel removing Texture mapping Color
interpolation (?) Antialiasing
Geometric Transformation Clipping Lighting (?)
Culling LoD
Depth buffer
Texture memory
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Commercial Systems - with mind of Culling/LOD

• Runtime libraries
• Performer, Inventor, Java3D, OpenGL Optimizer
• VRML97 based libaries
• VR systems
• WTK
• OpenGVS, Vega
• VRT
• Modeling Systems
• MultiGen
• SoftImage
• 3DS Max / Maya

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Practical Usability of Cull/LOD
Desired Draw Time
Time
DRAW
1 processor
SAVED
CULL
LOD
DRAW
Success
CULL
LOD
SAVED
DRAW
Fail
Success
3 processors
DRAW
CULL
LOD
SAVED
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Practical Usability of Cull/LOD

• 1 Processor
• Possibility of practically unusable algorithms
• decrease less DRAW time than the increased
  overhead of computation time (negative gain)
• gain saved time - compuational overhead in time
• 3 Processors
• Possibility of practically unusable algorithms
• takes more computational time than the desired
  DRAW time (frame time)
• Possible delay of the scene update

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Culling

• PerformerTM
• View frustum culling
• using scene graph hierarchy
• Grouping node type
• pfGroup,pfSCS, pfDCS,...
• Two levels of bounding volume
• Bounding sphere of pfGeode
• Bounding box of pfGeoSet
• User can specify bounding volume
• No automatic updates
• Dynamic objects
• (eg. merry-go-around)

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Image excerpt from IRIS PerformerTM Programming
Guide
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Culling

• OpenGL OptimizerTM
• View frustum culling using scene graph hierarchy
• bounding box of csGeoSet
• Occlusion culling
• eliminate objects for which a specified fraction
  of their bounding boxes are occluded by
  foreground objects
• partial occlusion control

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without culling
with view frustum culling
Images excerpt from OpenGL OptimizerTM
Programmers Guide
with view frustum culling and occlusion
culling
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Culling

• VRML97
• View frustum culling using scene graph hierarchy
• Bounding box defined in local coordinate for all
  grouping nodes
• Anchor, Billboard, Collision, Group, Inline,
  Switch, Transform

Transform eventIn MFNode addChildren
eventIn MFNode removeChildren
exposedField SFVec3f center 0 0 0 (- ?, ?)
exposedField MFNode children exposedField
SFRotation rotation 0 0 1 0 -1,1,(- ?, ?)
exposedField SFVec3f scale 1 1 1 (0, ?)
exposedField SFRotation scaleOrientation 0 0 1 0
-1,1,(- ?, ?) exposedField
SFVec3f translation 0 0 0 (- ?, ?) field
SFVec3f bboxCenter 0 0 0 (- ?, ?)
field SFVec3f bboxSize -1 -1 -1 (0, ?)
or -1,-1,-1
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Culling

• WTKTM
• View frustum culling using scene graph hierarchy
• Grouping nodes
• Anchor, Group, Inline, LOD, ROOT, Separator,
  Switch, Transform
• leaf nodes
• Geometry, Fog, Light, Transform
• Two levels of bouding volume
• Extents of node
• world axis aligned bounding box
• Radius and Midpoint of node
• Bounding sphere

Z axis
Y axis
radius
extents1Z
extents0Y
midpoint
extents1Y
extents0Z
X axis
extents0X
extents1X
Image excerpt from WTKTM Reference Manual Release
6
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Culling

• OpenGVSTM
• View frustum culling using objects hierarchical
  bounding boxs
• GV_obi_set_bbox_local()
• GV_obi_inq_bbox_local()
• GV_obi_inq_bbox_full()
• GV_obi_inq_bbox_full_world()
• Turn on or off culling
• GV_obi_set_culling_state()
• GV_obi_inq_culling_state()
• No special grouping nodes for the hierarchy
• GV_obi_dettach_child()
• GV_obi_attach_child()
• GV_scn_add_object()

Scene
objects
obd
obd
obi
obi
obi
obd
obd
obd
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Culling

• Why view frustum culling using the hierarchy of
  bounding volumes
• Big gain big saved time - small computational
  overhead
• If the uniformly distribution of objects and 60o
  field of view
• then more than 80 objects are culled

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LOD in Commercial system

• General process of the Virtual World management
• World creation (Modeling)
• World running (Runtime management)
• Multiresolution model generation
• In the modeling stage
• Generating models with multiple details from the
  original most detailed one
• LOD selection
• In runtime management stage
• Selecting an appropriate detail of the
  multiresolution model

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LOD in Commercial System

• Commercial systems with the modeling stage
• General Purpose 3D Modeling Tools
• MayaTM / 3DS MaxTM / SoftImageTM
• VR Oriented Tools
• MultiGenTM / VRTTM (SuperscapeTM )
• Commercial systems with the runtime management
  stage
• General 3D libraries
• PerformerTM / InventorTM / Java3DTM / OpenGL
  Optimizer / VRML 97TM based libraries
• VR runtime systems
• WTKTM / OpenGVSTM / VegaTM / VRTTM
  (SuperscapeTM )

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LOD in modeling stage

• MayaTM
• Multiresolution creation is supported
• Nurbs based surface modeling
• Multiresolution through Nurbs tessellation
  resolutions
• Multiresolution selecting in preview rendering
  mode
• Discrete selection
• Based on the distance

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LOD in modeling stage

• MultiGenTM
• Multiresolution Creation is supported as a basic
  feature
• Grid subsampling methods
• Discrete set of
• different detail models
• Morphing Mechanism

Images excerpt from MultiGen II ProTM Users Guide
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LOD in modeling stage

• 3DS MaxTM
• Multiresolution Creation is supported as a basic
  feature
• Face removing methods
• Face size / Edge angle / Edge length / Smooth
  based simplification
• Discrete set of different detail models

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LOD in modeling stage

• SoftImageTM
• Multiresolution Creation is supported as a basic
  feature
• Three methods
• Rule based
• Angle / Radius / Length / Area / Height
• Optimization based
• Choosing points from the generated point clouds
• Filter based
• Discrete set of different detail models

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LOD in modeling stage
Images excerpt from SoftImageTM 3D 3.5 Users
Guide
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LOD in modeling stage
Images excerpt from SoftImageTM 3D 3.5 Users
Guide
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LOD in modeling stage
Images excerpt from SoftImageTM 3D 3.5 Users
Guide
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Other LOD generator

• OpenGL OptimizerTM
• Built-in LOD generator
• Decimation Method
• vertexWeight W 0 distance W 1
  normalDeviation W 2 curvature
• Lattice Method

Images excerpt from OpenGL OptimizerTM
Programmers Guide
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Images excerpt from OpenGL OptimizerTM
Programmers Guide
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LOD Generator

• Why the most of the tools using simple
  algorithms?
• Complex algorithms requires a lot of patience of
  the user
• Interactive control over parameters with simple
  algorithms
• vs. Sub-optimal algorithms with a lot of waiting
  time
• Alternatives Let the user may intervene the
  process of the complex optimization (like
  SoftImage)
• Why the most of the tools using simple
  representations?
• Object-wise discrete detail levels
• Simple and easy to integrate in the existing
  scene graph

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LOD in runtime

• PerformerTM
• LOD node Grouping and selecting different
  detail geometric nodes
• Selecting using distance criteria
• Fade / Blending between two different levels

Image excerpt from IRIS PerformerTM Programmers
Guide
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LOD in runtime

• PerformerTM continued
• Frame rate control

Image excerpt from IRIS PerformerTM Programmers
Guide
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LOD in runtime

• PerformerTM continued
• More sophisticated detail control For Terrain

Image excerpt from IRIS PerformerTM Programmers
Guide
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LOD in runtime

• InventorTM / Java3DTM / VRML97 / OpenGL
  OptimizerTM
• LOD node based selector

Images excerpt from OpenGL OptimizerTM
Programmers Guide
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LOD in runtime

• WTKTM (R8) / OpenGVSTM / VEGATM / VRTTM
  (SuperScapeTM )
• Basically performer based systems

Images excerpt from WTKTM R8 Reference Manual
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LOD in runtime

• Selector in general
• Scene graph level selector
• Easy and simple representation
• Selector for the specific object type
• Terrain
• Tightly coupled with the object internal
  representation mechanism