Janek Press

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Janek Press janek.press_at_ut.ee University of
Tartu October 1st 2008
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Legend

• About Eurographics
• Human Perception and Computer Graphics
• Papers from Eurographics 2008
• Parallel Graphics
• Papers from Symposium on Parallel Graphics and
  Visualization 2008

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European Association for Computer Graphics
Eurographics is the only truly Europe-wide
professional Computer Graphics association. The
association supports its members in advancing the
state of the art in Computer Graphics and related
fields such as Multimedia, Scientific
Visualization and Human Computer
Interfaces. Through a world-wide membership, EG
maintains close links with developments in the
US, Japan and other countries, promoting the
exchange of scientific and technical information
and skills on a global scale.
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Eurographics Publications

• Digital Library
• The Eurographics Digital Library Archive is
  freely accessible regarding the bibiographic and
  the metadata content. Only the access to most of
  the full-text documents is restricted to
  Eurographics members with an electronic
  subscription option or to people from
  institutions which have an Institutional
  Membership in Eurographics.
• Computer Graphics Forum
• The international journal Computer Graphics
  Forum (CGF) is jointly published by the
  Eurographics Association and Wiley Blackwell. CGF
  is a leading journal for in-depth technical
  articles on computer graphics.

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Eurographics Annual Conference

• This year in Crete, Greece

Next year in Munich, Germany
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EG08

• Role of Perception for Computer Graphics
• Render2MPEG A Perception-based Framework Towards
  Rendering and Video Compression
• Apparent Grayscale A Simple and fast Conversion
  to Perceptually Accurate Images and Videos
• Tutorial Designing multi-projector VR systems
  from bits to bolds
• Tutorial Perceptually-Motivated Graphics

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Role of Perception for Computer Graphics

• Traditionally computer graphics strived to
  achieve the technically best representation of
  the scenario or scene
• Rendering representations based on physics of
  light interacting with different media and
  materials
• VR focus on interacivity and real-time
  techniques to improve the immersion
• Visialization representations that maimize the
  information content
• Integration of knowledge and methods from
  perceptual research into computer graphics
• Fundamental changes
• New research questions
• New ways of solving old ones

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Render2MPEG A Perception-based Framework Towards
Rendering and Video Compression

• Couple renderer and MPEG codec
• Precise motion vectors to codec
• Perceptual error threshold for each pixel to
  renderer
• DCT coefficents on the codec side enable to use
  advanced models of the HVS in the perceptual
  error threshold derivation without significant
  cost. Those thresoholds are used to control
  rendering quality, to align it with compressed
  stream quality

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Apparent Grayscale A Simple and fast Conversion
to Perceptually Accurate Images and Videos

• Globally assigne grey values and determine colour
  ordering
• Image independent, incorporates
  Helholtz-Kohlraush colour appearance effect for
  predicting differences between isoluminant
  colours
• Locally enhance the greyscale to reproduce
  original contrast
• Reintroduces lost discontinuities only in regions
  that insufficiently represent original chromatic
  contrast
• All operations are restricted so that they
  preserve the overall image appearance, lightness
  range and differences, colour ordering and
  spatial details

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Designing multi-projector VR systems from bits
to bolds

• Different lamp types
• Stereoscopy active vs passive
• Projection and Screen Geometries
• Calibration, synchronization
• Projector arrays
• Color
• User tracking
• Multimodeal interfaces

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Perceptually-Motivated Graphics

• HVS Human Visual System
• Not all parts of visble scene are of same
  interest
• Information slots which have not been filled with
  perceptual information, are filled be default
  assignements based in stereotypic expectations
  from past experience
• Virtual Reality systems
• Users notify latency of 15ms 75 probability
• Depends on scenery

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EGPGV08

• Multi-GPU Sort/Last Valume Visualization
• Streaming Model Based Volume Ray Casting
  Implementation for Cell Broadband Engine
• High-Fidelity Rendering of Animations on the
  Grid A Case Study
• CUDASA Compute Unified Device and System
  Architecture
• Parallel Volume Rendering on the IBM Blue Gene/P

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Multi-GPU Sort-Last Volume Visualization

• Multiple GPUs, single CPU no networking
• Each GPU renders a brick of data
• 3D texture based slicing
• Raycasting
• Compositing
• CPU blend pictures back-to-front
• GPU sort intermediate pictures on CPU, using
  back-to-front or front-to-back technique depends
  on the target GPU
• GPU technique 3x faster, scales to 4 nodes

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Streaming Model Based Volume Ray Casting
Implementation for Cell Broadband Engine

• Cell B.E. thoeretical peak 204 GFlops/s
• PPE 64-bit PowerPC Processor Element
• 8x SPE Synergistic Processor Elements, 3.2GHz
• SPU Synergic Processor Unit
• 128-bit wide SIMD 4-way 32-bit floating point
  operations
• MFC Memory Flow Controller
• LS 256kB local storage
• EIB Element Interconnect Bus, 204GB/s
• Raycasting acceleration techniques
• Empty space skipping (PPE)?
• Early ray termination (SPE)?

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High-Fidelity Rendering of Animations on the
Grid A Case Study

• Parallel rendering
• Shared memory machines
• Small to medium clusters
• Grid
• Massive parallelism
• Multi-user environment
• Relatively low inter-node communication
• Sharing irradiance cache, 2-pass method
• Expoit temporal coherence between animation
  frames, no extra data structures required

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CUDASA Compute Unified Device and System
Architecture

• CUDA C-style programming language for GPGPU
• Higher level of parallel abstraction from bus and
  network interconnects
• Multi-GPU
• GPU-clusters
• CUDASA compiler
• CUDA code
• Multi-threading application code
• MPI network communication

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Parallel Volume Rendering on the IBM Blue Gene/P

• Distributed-memory parallel architecture
• BG/P 4096 cores, soon 128K cores
• PowePC 450 850MHz, 2-way SIMD
• Measuring performance
• Disc I/O up to 64TB, MPI-2
• Rendering
• Compositing
• Scaling efficiency
• 128 cores 50
• 4096 cores - 25

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Thank You!