BBB: BBB Computer Graphics Systems Group, Hasso-Plattner Institute, University of Potsdam,


Outline: Outline ¨ Introduction & Basic Concepts ¨ Generalization Concept ¨ Implementation ¨ Applications ¨ Conclusions


Mission: Unified Rendering Technique: Mission: Unified Rendering Technique Unify techniques for: Non-planar projections 2D lens effects Image warping Implementation requirements: Real-time visualization Large scene rendering Single projection center (SCOP)


Basic Concept – Overview : Basic Concept – Overview Components: Dynamic cube map Screen-aligned quad Fragment shader 3-Phase rendering: Create/Update dynamic cube map Setup projection shader Render screen-aligned quad Main characteristics: Image-based approach Fully hardware accelerated Cube map


Basic Concept – Details : Basic Concept – Details Define projection function: Apply camera orientation: Sample from cube map:


Example: Cylindrical Projection: Example: Cylindrical Projection Projection function: Horizontal Vertical Horizontal FOV: 360°, Vertical FOV 60°


Example: Spherical Projections: Example: Spherical Projections Projection function: Viewport truncation: A B C


Optimization: Normal Maps: Optimization: Normal Maps For static projection functions Store normalized cube map sampling vectors Using Render-To-Texture (RTT) Floating point texture precision


Outline: Outline þ Introduction & Basic Concepts ý Generalization Concept ¨ Implementation ¨ Applications ¨ Conclusions


Generalization Concept – Overview : Generalization Concept – Overview A B C D


Projection Tile Screen - Example: Projection Tile Screen - Example Final Rendering


Projection Tile Screens: Projection Tile Screens Projection tile screen (TPS)=set of projection tiles Projection tile=set of tile features Tile Feature:


Generating Feature Maps: Generating Feature Maps Feature-map rendering: Setup render-to-texture Setup orthogonal-projection Encode feature properties as color values: Angles: Render tiles successively Cube map sampling vectors: Calculated using fragment shader Vector derived by:


Projection Tiles – Extensions : Projection Tiles – Extensions Limitations: PTS is hard to model and control Triangulation influences interpolation Covers not all possible tile shapes No hard transition between tiles Improvements: Regular grid  triangulated planar mesh („triangle soup“) Enables hard transitions between tiles Enable the usage of modeling tools


Outline: Outline þ Introduction & Basic Concepts þ Generalization Concept ý Implementation ¨ Applications ¨ Conclusions


Dynamic Cube Maps: Dynamic Cube Maps Single-Pass: needs DX10 compatible hardware Evaluate the scene only once Geometry shader multiply primitive Project primitive to cube map faces Rasterization to six texture layers in parallel Multi-Pass: most compatible approach Evaluate scene six times RTT to each cube face Runtime optimizations: Omit whole cube map update Omit cube map side update


Main Shader: Main Shader Shader main entry point


Cylindrical Projection Shader: Cylindrical Projection Shader Projection function


Outline: Outline þ Introduction & Basic Concepts þ Generalization Concept þ Implementation ý Applications ¨ Conclusions


Non-Planar Projection Surfaces: Non-Planar Projection Surfaces Horizontal FOV: 360°, Vertical FOV 90° Normal Map Final Rendering


Using Custom Normal Maps: Using Custom Normal Maps Final Rendering Horizontal FOV: 90°, Vertical FOV 60°


Combinations of Projections: Combinations of Projections


Lens Effects: Lens Effects Horizontal FOV: 180°, Vertical FOV 135° Final Rendering Normal Map


Compound Eye: Compound Eye Horizontal FOV: 120°, Vertical FOV 60°


Outline: Outline þ Introduction & Basic Concepts þ Generalization Concept þ Implementation þ Applications ý Conclusions


Limitations: Limitations Rendering quality depends on: Cube map resolution Tessellation of tile screen Undersampling / Oversampling Dynamic cube map can be costly Interpolation artifacts by contrary tessellation Haik Lorenz, Jürgen Döllner, Dynamic Mesh Refinement on GPU using Geometry Shaders, WSCG 2008 (to appear) A B


Conclusions: Conclusions Take aways: General concept for SCOP distortions: Non-planar projections 2D lenses with arbitrary shapes Image warping and distortions Applicable in real-time for large scenes Controllable via projection tile screens Important: resolution of cube map and tessellation of PTS Future work: Improve rendering quality Develop graphical user interface for PTS Shift PTS tessellation to GPU


Q & A: Q & A Thank You. Contact: Matthias Trapp matthias.trapp@hpi.uni-potsdam.de Computer Graphics Systems Group Prof. Dr. Jürgen Döllner www.hpi.uni-potsdam.de/3d Research group 3D-Geoinformation www.3dgi.de