2. Eikonal Rendering: View Renderer
refEiko - View renderer
“Eikonal Rendering: Efficient Light Transport in Refractive Objects”, Ivo Ihrke, Gernot Ziegler, Art Tevs, Christian Theobalt, Marcus Magnor, Hans-Peter Seidel

3. Overview: 2 main components
System capable of Refractive Object Rendering:
Light Simulator (pre-process, ~10 secs)
View Renderer (real-time, 5-60 fps)
To efficiently map our concepts onto the GPU we have developed new algorithms and data structures that enable us to strongly accelerate
light simulation and achieve real-time view rendering performance. We use a volumetric scene representation to store all relevant
data in textures, such as refraction indices, their local gradients and attenuation values describing the local energy loss due to material properties.

4. Renderer Shader Model >= 3.0 GPU
Use OpenSceneGraph (v1.2) for the low level tasks, e.g. transparency sorting, mesh rendering, etc.
nrEngine: script handling, resource management, …
Volume Ray Casting
- Renderer implements the image formation model of our algorithm
- Implemented on SH4.0 but can run on SH3.0 hardware
- For ray propagation use the ray casting principle (shooting rays from camera through the object)‏
- Thus try to find a solution for the volume rendering integral

5. Scene Graph based rendering (depth and transparency sorting)
OpenSceneGraph for rendering the meshed environment,
It gives us also Depth and Transparency sorting
Refractive objects can be seen from the other one but by one frame difference (since the envmap is rendered before volume object)‏

6. Renderer Full HDR color along complete rendering pipeline
Post processing by PPUG (post-processing units graph)
Completely scriptable

7. Scene Representation XML description of a complete scene
Supported objects:
Camera
Light
Shader
Texture
Model (Mesh)
Entity (Static, Voxel Volume)
Environment Map (CubeMap, PlaneMap, ShadowCubeMap)
Post Processing Unit

8. Scene graph Root Node Environment Renderable Map Root Node Entity
Light Group
Light 1
Light 2
Mesh (Geode)
Mesh (Geode)

9. Volume rendering Volume rendering is required for our approach
VoxelVolume class stays for an osg node handling volume rendering
VoxelVolumeDrawable derived from osg::Drawable, implements volume rendering by a shader program
Rendering by a proxy geometry (ray casting)
Box primitive (default)
Geode as a child-node

10. Post Processing Effects
Post processing by a so called PPU, post processing unit
PPUs are combined into a graph
Multiple inputs for each of PPU (osg::Texture)
Multiple outputs (MRT) are implemented, but not well tested ;-(
PPUG could contribute to osg as a new node kit

11. PP Effects (HDR bloom, Depth of Field, Motion Blur, [+ tone mapping])
Post Processing effects.
Renderer implements a ppu graph
Result after the volume ray casting is stored in a 16bit float texture.
blooming or glowing, depth of field and motion blur are done in HDR
at the end an adaptive tone mapping approach

12. Post Processing Units Graph (Depth of Field)
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
Taken from

13. Post Processing Units Graph (HDR Bloom + tone mapping)
DoF Result
Downsample
Compute avg.
luminance
Compute scaled
luminance
Brightpass
Downsample
Blur vertical
Blur horizontal
Tone mapping
Based on

14. Summary & Future work Nice renderer for our approach
HDR rendering and scripting
Osg 2.x is supported, but not well tested
osgLua implementation required
Possible contribution to the community by developing a new node kit osgPPU
New SH4.0 features are in development, hence new contribution to osg will follow: Texture2DArray, GeometryProgram, …

15. Advertisement
Visit our implementation sketch at Thursday, 9th August, Room 3 at San Diego Convention Center: GPU-based Light Wavefront Simulation for Real-Time Refractive Object Rendering
Google for Eikonal Rendering or just go to : and download slides, videos and source code.
Visit my Homepage ;-)

16. Discussion & Demo