Interactive Context Driven Visualization Tools for Augmented Reality

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Interactive Context Driven Visualization Tools
for Augmented Reality

• Erick Méndez, Denis Kalkofen, Dieter Schmalstieg

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Context Driven Tools

• Affect regions defined by magic lenses
• Affect according to contextual information
• Apply any possible rendering style change
• Multiple volumetric convex shapes

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Context Driven Tools
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Magic Lenses

• Introduced by Bier et al. in 1993
• Reveal hidden information
• Enhance data of interest
• Suppress distracting information
• Ropinski et al.
• Multi pass rendering 3D volumetric magic lenses

Bier et al. 1993
Ropinski et al. 2004
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Context Sensitive Scene Graph

• Scene graph framework
• Studierstube
• Problem
• Information scattered throughout scene graph
• Requires full search
• May require multiple manipulations
• Complicated by mix-and-match scene graph
  composition

search
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Context Sensitive Scene Graph

• Generic parameterization during traversal
• Reitmayr et al.
• Add generic parameter passing technique
• Binding of parameters happens during traversal
• Evaluated in the last possible moment
• Part of the complexity shifted to the data
  structure
• Based on existing standard scene graph
• Scene graph becomes a template structure - Collada

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Traversal and State

• Scene graph

• State stack

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• Transformation
• Material parameters
• Light sources

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Context Sensitive Magic Lenses

• Affect regions defined by magic lenses
• Objects grouped by context families
• Attach styling subgraph depending on contextual
  information
• Multiple volumetric convex shapes

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Context Families and Styling Subgraphs

• Subgraphs with contextual information
• Affected regardless of position in scene graph
• Build specialized subgraphs during traversal

• Arbitrary subgraphs
• Material
• Transformations
• Shape Nodes
• Result depends on scene graph behavior

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Rendering and Scene Graph

• Objects grouped by context families
• Every family precedes a styling subgraph
  depending on context
• Objects on context families rendered three times,
  behind, inside and in front lenses

Node in context family
Behind
In front
Styling subgraph
Inside
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Rendering and Scene Graph

• Ropinskis three pass technique
• Lenses depth information is encoded in textures -
  FBO
• Depth-textures used to determine 3D position of
  every fragment
• Magic lens is only a region
• Not anymore a styling tool

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Multiple Volumetric

• Use multiple textures
• Find containers of every fragment
• Multiple lens intersection built by concatenation
  of styling subgraphs
• Concave lenses
• High number of passes required

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Multiple Volumetric

• Hepatica - Red
• Porta - Blue
• Tumors - Green

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Pros and Cons

• Avoid searching
• Scene graph decomposition of styles and objects
• Dynamic styling of nodes
• Exploits contextual information
• Multiple arbitrary convex shapes

• Complexity shifts to scene graph data structure
• Results depend on scene graph behavior
• Control depends on contextual detail
• Number of passes
• Caching

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Applications

• Real data has context
• Important in AR
• Implicit user interaction
• Exploits contextual information
• Interaction does not depend on the tool but on
  the information itself

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www.studierstube.org
Funded by The Austrian Research Promotion Agency
(FFG)