Onyx2 Architecture Overview

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Onyx2 Architecture Overview
Curtis Lisle, Ph.D. Visual Systems
Scientist Silicon Graphics Computer Systems
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SGI Onyx2 Image Generator Overview
CPUs
High-speed crossbar interconnection Host and
host interface functions Database traversal,
cull, and draw processes
Digital Video Processor (distortion and extra
pixel fill)
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(No Transcript)
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The Legacy Host/graphics Architecture

• Front-end host computer with a separate but
  connected Image Generator (IG)
• Problem of access to a remote database

Host
Simulation Functions
Protocol for eye and object position, Database
queries, updates,
network
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The SGI Image Generator Architecture

• Integrated Computing and Graphics
• Local, shared memory database access
• CrayLink (800 MB/sec bidirectional) to/from
  rendering engine
• Multi-pass special effects rendering

Host
Graphics
DB Dynamics
Environment Database
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Embedded Host Architecture

• Multiple processors with high-speed
  interconnection fabric between them improves
  performance, reduces latency, and delivers more
  bandwidth into the graphics pipeline

Application
Graphics
Graphics Pipeline
1.1.1Onyx2 Deskside Image Generator
Geometry Engine
Raster Manager
Display Generator
1.1.1Onyx2 Deskside Image Generator
I/O Subsystem
Environment Database
Other simulation information or source data

Multiple Video Outputs

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SGI Run-Time Software Architecture

• Run-Time Software Architecture
• Application program - Handles host functions
  and/or user interaction makes Performer API
  calls
• Performer - manages scene graph representation
  processor allocation optimized for hardware
• Industry Standards - Authored by SGI

Simulator Application
Performer Run-Time API
OpenGL
Host
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Anti Aliasing

• SGI InfiniteReality systems have a
  multisampling feature allowing sub-pixel
  calculations for each pixel actually on the
  screen at near full performance.

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Anti-Aliasing and Priority

• Granularity of priority resolution (depth
  buffering) has a strong effect on the quality of
  the anti-aliasing
• Subsample, or fragment level depth buffering
  necessary for correct pixel color calculations

Primitives
No contribution by red, blue, or green polygon if
Z buffer works at pixel level (such as jittered
eye points)
Resolved pixel
SamplePoint
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Subsample Anti-Aliasing

• Quality AA solution uses fragment Z as well as
  color to compute resolved pixel color
• Multi-sample, or screen door transparency, can
  weight the fragment colors based on alpha
  yielding order-independent transparency

Primitives
Sample pattern masks are optimized for AA on
angled primitives - can be shifted
Resolved pixel
SamplePoints
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Color Displays

• The Frame Buffer (graphics memory)
• 24 bits 8-bits R,G,B 224 16.7 Million
  Colors
• SGI InfiniteReality VPro can have 10 or 12
  bits per component
• SGI InfiniteReality Up to 320MB for color and
  up to 256MB for texture
• SGI Octane/VPro has up to 128MB
• Highest-end PC cards have 64MB for color and
  texture

Display
Graphics subsystem
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Display Processing Features

• Necessary for high quality, abutted or blended
  visuals
• Framelock
• All screens of video output from the image
  generator have synchronized vertical retrace
  signals. Top to bottom picture-painting is
  aligned.
• Genlock
• Sync multiple pixel clocks
• Swapready
• All channels ready for swapping backbuffer
• Programmable video output

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Video Configuration

• IRcombine interactive program
• /usr/gfx/setmon
• /usr/gfx/ircombine
• Allows choice of predefined video formats
• VFC (video format compiler) for non-standard
  formats
• References
• Video Format Compiler Programmers Guide
• SGI TechReport (007-3402-003)

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Invoking a Video Format
Invocation Commands
/usr/gfx/setmon ltformatgt e.g. /usr/gfx/setmon
1280x1024_72 xsetmon IRcombine
Location of format files (system specific)
/usr/gfx/ucode/
KONA/dg4/cmb/ltformatgt.cmb (Onyx/IRx)
ODSY/vof/ltformatgt.vfo (Octane/Fuel
Vpro)
MGRAS/vof/ltformatgt.sdb (Octane SI/SE)
MGRAS/vof/2RSS/ltformatgt.sdb (Octane
SSI/MXI/SSE/MXE)
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Building a Format
User supplied
Video source text file ( .vfs )
SGI Software
Video Info File ( .info )
Video Format Compiler ( VFC )
Video Format File ( .vfo )
Board Definition File ( .def )
Chip Definition File ( .def )
/usr/gfx/ucode/...
Copy to
Hardware specific rules files. SGI supplied.
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Video Format Source (.vfs)
General ActiveLinesPerFrame
ACTIVE_LINES ActivePixelsPerLine
ACTIVE_PIXELS FramesPerSecond FPS
FormatName FieldsPerFrame 1
TotalLinesPerFrame 1.05 ActiveLinesPerFrame

Active Line HorizontalFrontPorch pixels(
iHFPp ) HorizontalSync pixels( iHSp )
HorizontalBackPorch pixels( iHBPp )
Field lt statements defining the field gt
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Compiling and Rules Definition Files
vfc -a asciijk1280x768_48.info -c
chipvoc1.def,boarddg4.def \ -o
jk1280x768_48.vfo jk1280x768_48.vfs
Graphics Chip def. Board def. IR voc1.def dg4.d
ef O2 O2_Chip.def O2_Board.def MGRAS mgras_vc3.d
ef mgras.def VPRO Vpro_Chip.def Vpro_DCD.def
Rules definition files found in /usr/gfx/ucode/vf
c/rules/ Sample format sources found
in /usr/gfx/ucode/vfc/vfs/
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Example Passive Stereo(with standard stereo
apps)
Polarizing filters 90-degrees out of phase
Eyewear
Onyx
Framebuffer
Channel 0
Left
Projectors
Channel 1
Right
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Example Passive Stereo(with standard stereo
apps)
- Make 2 Copies of std format source
1280x1024_60.vfs 1280x1024_60L.vfs and
1280x1024R.vfs - Add eye parameter to the
Field sections.
- Create a combination using IRcombine with
1280x1024_60L.vfo and 1280x1024_60R.vfo 100
overlap.
Field eye Left Vertical Sync
. . .
Field eye Right Vertical Sync
. . .
1280x1024_60R.vfs
1280x1024_60L.vfs
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SGI O2 Measuring signals

• Using SGI Tools (O2)
• colorbars
• videoout
• videopanel
• confidence
• audiopanel

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Measuring video signals

• Waveform and Vectorscope

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Video Links

• Encyclopedia Britannicahttp//www.britannica.com/
  
• How Stuff Workshttp//www.howstuffworks.com/
• Color Theory Pagehttp//www.barco.com/display_sys
  tems/support/colorthe/colorthe.htm
• Video Demystifiedhttp//www.video-demystified.com
  /
• Video Technology Pagehttp//www.epanorama.net/vid
  eo.html
• A guide to MPEG fundamentalshttp//www.tek.com/Me
  asurement/App_Notes/mpegfund/
• The Lurkers Guide to Video (Chris
  Pirazzi)http//www.lurkertech.com/lg/
• Techpubshttp//techpubs.sgi.com/

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Conclusion

• The SGI Onyx architecture has unparalleled
  support for multimedia
• Shared memory supports tightly-coupled graphics
  pipe coordination for large screen displays
• Software is standard unix development environment
• Large amount of commercial and freeware available
• The Onyx is an ideal foundation for creative
  talent to use during creation and replay of
  custom 3D worlds