Art Tevs, Saarbrcken, Germany

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• Art Tevs, Saarbrücken, Germany

osg-user-meeting, Paris, april 2008
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Overview

• About Me
• publications
• projects
• osgPPU
• overview
• classes
• examples

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About Me

• Art Tevs, born in Russia, living in Germany
• Master Degree in Computer Science in University
  of Saarland, Saarbrücken, Germany
• PhD student in Max-Planck-Institut Informatik,
  Saarbrücken, Germany
• research topics rendering, natural phenomena,
  GPUs, geometry processing (just started)?

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About Me (publications)?

• Siggraph07, I. Ihrke, G. Ziegler, A. Tevs, C.
  Theobalt, M. Magnor, H.-P. Seidel, "Eikonal
  Rendering Efficient Light Transport in
  Refractive Objects"
• realistic rendering of refractive objects with
  spatially varying properties (refractive index,
  attenuation, scattering, ...), first time using
  OSG and osgPPU

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About Me (publications)?

• I3D08, A. Tevs, I. Ihrke, H.-P. Seidel, "Maximum
  Mipmaps for Fast, Accurate, and Scalable Dynamic
  Height Field Rendering"
• quadtree-like datastructure for efficient
  ray-heightmap intersection on the GPU (usuable
  displacement mapping), using osgPPU for
  computations

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About Me (projects)?

• osgPPU ( http//projects.tevs.eu/osgppu )?
• developed during the Siggraph07 project
• offscreen renderer using GLSL shaders for
  computations
• used for post-processing effects
• used to compute maximum-mipmap in the I3D08
  project
• working hard on v0.2 release
• osgPlugins/osgdb_ppu to read/write osgPPU graphs
  from/to .ppu files

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osgPPU

• Screenshot from Eikonal Rendering (Siggraph07)?

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osgPPU

• Screenshots from Maximum Mipmaps (I3D08)?

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osgPPU

• Processor
• derived from osgGroup
• can be placed anywhere in the scene graph
• contains camera pointer to retrieve texture
  attachments and viewport data
• do initialize, optimize, update and draw PPU
  graph
• resolve cycles in the Unit graph by placing a
  BarrierNode which blocks the traversion

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osgPPU

• Unit (base class)?
• derived from osgGroup
• should be placed in the processor's subgraph
• collect Input data (textures) from the parent
  Units (output textures) or from processor (camera
  attachments)?
• connect input Unit to specified uniform (usefull
  for shader parameters)?
• a lot of virtual functions to override in derived
  classes

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osgPPU

• UnitBypass
• derived from osgPPUUnit
• perform no rendering
• do just set OutputTexture InputTexture
• very usefull to just bypass the data for example
  from the processor's camera
• UnitDepthbufferBypass
• derived from osgPPUUnitBypass
• perform no rendering
• bypass the processor's camera depthbuffer
  attachment
• usefull to bring the depthbuffer texture into the
  PPU graph

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osgPPU

• UnitTexture
• derived from osgPPUUnit
• perform no rendering
• bypass a user specified input texture (external
  texture) to the output
• very usefull to bring external data into the PPU
  graph

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osgPPU

• UnitInOut
• derived from osgPPUUnit
• render a 2D screenquad to perform computation on
  the input data
• use FrameBufferObject (FBO) to setup the output
  texture
• supports MRT by moving the MRT setup code into
  the FBO patch for the new osg v2.4
• UnitInResampleOut
• derived from osgPPUUnitInOut
• same as UnitInOut however resample the output
  texture by specified factor

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osgPPU

• UnitInMipmapOut
• derived from osgPPUUnitInOut
• same as UnitInOut however the output texture is
  mipmapped
• compute the mipmap data by either applying the
  glGenerateMipmapsEXT or the attached Shader
  program
• UnitText
• derived from osgPPUUnitInOut
• don't render the 2D quad, bypass the input to the
  output
• render an osgTextText on the output texture
• very usefull to render text into a texture

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osgPPU

• UnitOut
• derived from osgPPUUnit
• perform as UnitInOut but don't use FBO
• used to render the input to the frame buffer
• usualy the last unit in the osgPPU graph to bring
  the computed result to the screen
• UnitOutCapture
• derived from osgPPUUnitOut
• same as UnitOut but after the rendering write the
  input texture to a file
• very usefull to capture screen contents in upto
  4K resolution (8K on G80 chips)?

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osgPPU (examples)?

• viewer
• a simple viewer for the .ppu files
• ./viewer file.ppu scene.osg default teapot
• dof
• a simple faked depth of field effect with
  osgPPU
• ./dof scene.osg default cow.osg
• hdr
• shows implementation of HDR rendering
• ./hdr scene.osg default teapot

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osgPPU (examples - DoF)?
DoF resample 0.5
DoF resample 0.5
DoF blur horizontal
DoF blur vertical
DoF blur horizontal
DoF blur vertical
Color bypass
DoF Result
Depthmap bypass

• http//www.daionet.gr.jp/masa/archives/GDC2003_DS
  TEAL.ppt

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osgPPU (examples - DoF)?

• http//www.daionet.gr.jp/masa/archives/GDC2003_DS
  TEAL.ppt

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osgPPU (examples - HDR)?

• http//msdn2.microsoft.com/en-us/library/bb173484.
  aspx

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osgPPU (examples - HDR)?

• http//www.daionet.gr.jp/masa/archives/GDC2003_DS
  TEAL.ppt

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• Thank You!
• Questions, Discussion, French-Beer...