Project Raytracing

Project Raytracing

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

Ray casting

Our Ray Caster

From Ray Casting to Ray Tracing

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

Lightmodel• Used: Phong reflection model• 3 types of light: ambient, diffuse, specular

=

Ambient and Diffuse

The coefficient is specific for a material

Specular

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

Video link 1

Video link 2

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)

Achievements

Light effectsAnimation renderingDifferent shapesAntialiasing

ImprovementsRefraction and transparencyTextures and noiseDepth of FieldImage mappingBounding VolumeRadiometry (power, energy, radiance...)Photon mapping

Thanks!

Thank you for your attention!

Questions?