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Project Raytracing. Content. Goals Idea of Raytracing Ray Casting Therory Practice Raytracing Theory Light model Practice Output images Conclusion. Specifications. Ray tracer depends on how to represent objects Parametric equation for precision, not rapidity - PowerPoint PPT Presentation
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Content• Goals• Idea of Raytracing• Ray Casting
– Therory– Practice
• Raytracing– Theory– Light model– Practice
• Output images• Conclusion
SpecificationsRay tracer depends on how to represent objects
Parametric equation for precision, not rapidity
Develop a Ray Tracer in order to explore a new intersection algorithm
Two teams :
- for mathematics
- for code
Main principleCreate 3D pictures
Mathematical equation
Throw ray from eye to pixels
Not FROM source light: TO it
Number of reflections
Great pictures but slow
AlgorithmsRay casting
- first method
- no bounce
Ray tracing
- from eye to pixels
- reflection
- refraction
- shadow
Fields of useAnimation studio
Pixar: with parsimony
→ light effects
Video games
→ with triangles
→ faster and great
Ray casting
For each pixel:
● Shoot a ray from the observer to the position of the pixel
● Test if the ray hits an object in the scene
● If there is a hit:
the color of this pixel will be the color of the object● If there is no hit:
the pixel receives the color of the background
Ray casting
What do we need ?● A position for the observer (eye, camera)● A direction/object to look at (and a « way
up »)● An object to show on screen● A representation of the 2D screen in the 3D
space
From Ray Casting to Ray Tracing
We add :● Lights
ambient, diffuse, specular● Shadows● Reflexion
=> recursion : another ray is shot from the intersection
● Material properties
ambient, diffuse, and specular coefficients
Shadows• Only add diffuse and
specular light, if a lightsource is visible
• Test for intersections between a point on the sphere and the lightsource
From Ray Casting to Ray Tracing
We add :● Lights
ambient, diffuse, specular● Shadows● Reflexion
=> recursion : another ray is shot from the intersection
● Material properties
ambient, diffuse, and specular coefficients
Interesting modules● Positionning of the screen in 3D space● The RayTracer class
● That's the core of the program (light model)● Shadows
● The use of inheritance to compute intersections● Obtaining an animation
● Camera and lights movement● Export a sequence of images, make a movie
● The Draughtboard
Difficulties
- math libraries- C++, compilation, building environment- Screen implementation- Unexpected results (debugging)
ImprovementsRefraction and transparencyTextures and noiseDepth of FieldImage mappingBounding VolumeRadiometry (power, energy, radiance...)Photon mapping