Transcript Real-Time Ray Tracing

Real-Time Ray Tracing
3D Modeling of the Future
Marissa Hollingsworth
Spring 2009
OBJECTIVES
• Current method: Rasterization
• What is Ray Tracing?
• Ray tracing Algorithm
• Applications
• Why ray tracing? Why not?
• Conclusions
• Questions?
Current Method: Rasterization
• Current leader for rendering 3D graphics
• Implemented on most standard GPUs
– Meaning speed and efficiency
• Takes one triangle at a time, projects it to the
screen and paints all covered pixels
– linear complexity with respect to scene size:
– Requires additional shading/shadow/texture
algorithms
What is Ray Tracing?
• Technique for rendering 3D
graphics
• Accurately imitates properties of
light rays
–Reflection, Refraction, Shadows
• Allows for global illumination
http://www.oyonale.com/modeles.php?lang=en&page=40
Ray Tracing Algorithm
1. Scene Description
2. Ray Generation
Viewpoint
Light Source
3. Ray Traversal
4. Object intersection
5. Shadow rays
6. Recursive reflection
and refraction rays
7. Pixel coloring
Image
Scene Object
Applications: Video Games
Oasen
Quake III
• First game using ray tracing
• Complex illumination model for
daytime, weather conditions etc.
• Collision detection using rays
• Simple code for realistic effects
Interactive Global Illumination
• Simulating global lighting through tracing rays
• Greatly increases realism by adding global lighting
effects
With
Without
Wald, I., Kollig, T., Benthin, C., Keller, A., and Slusallek, P. 2002. Interactive global illumination using fast ray tracing.
Massive Modeling
Scales
logarithmically
with scene size
Can render
entire CAD
models
without
simplification
Why Ray Tracing?
•
•
•
•
Highly realistic images
Physical correctness and dependability
Ease of implementation
Highly efficient
–Parallel computations
• Ray reuse (i.e. distance detection)
VW Beetle With Correct Shadows and Reflections
Slusallek, P., Shirley, P., Mark, W., Stoll, G., and Wald, I. 2005. Introduction to real-time
ray tracing. In SIGGRAPH '05: ACM SIGGRAPH 2005 Courses. ACM, New York, NY, USA,
1.
Why Not?
• Slow rendering times
• Not fully supported in hardware…yet
–Mostly implemented in software
–Programmable RPU (Ray
processing unit)
• Computationally expensive!
Summary
• Ray tracing renders highly realistic 3D models
• Allows for efficient computations, but SLOW
• Many useful applications
• Not feasible for real time implementation in
near future…but eventually!
QUESTIONS?