Presentation ofLR2V

Kadi BouatouchIRISA

Email: kadi@irisa.fr

Course: LR2V No prerequisite

French: Lancer de Rayon, Rendu et Visualisation

English: Ray Tracing, Rendering and

Visualization

Context

• Representation and visualization of things which do not exist– Create 3D virtual worlds

• Choose the model of the objects we want to represent

– Visualize them or simulate wave propagation• Choose a representation model• Choose its appearance• Choose a visualization method (rendering)

– Animate these worlds

Interest in 3D virtual worlds• Computer aided design• Manufacturing• Movies• Entertainment: video games• Data Visualization• Virtual Reality• Working without risk• Simulation• Acoustics

Application

Application

Application

Application

Application

Application

Application

Rendering Engine

Geometric Model

Appearance Model

RenderingEngine

Rendering Engine

• Real-time– Z-buffer

• 10 images per second >> 0,1s• 25 images per second >> 0,04 s• 60 images per second >> 0,016 s• 120 images per second >> 0,008 s

• Non real-time (also for acoustics simul)– Ray Tracing, Path Tracing, Photon Mapping– Radiosity

Ray Tracing: Principle

Y

X

Z

eye

screen

incident ray

worldcoordinates

scenemodel

nearestintersected

surfacerefracted

ray

reflectedray

shadow“feeler”

ray

Ray Tracing: Principle

Ray Tracing: Principle

View point Screen

Reflected ray

Shadow ray

Normal Primary ray

Refracted ray

Contents• LR2V - tronc commun

– Deterministic Ray Tracing• Geometric computation : intersection, hierarchy of bounding

volumes • Illumination model: reflection, refraction• Acceleration : methods of subdivision into cells: 3D, BSP

tree, KD-Tree, Octree, Uniform Grid– Stochastic Ray Tracing: Monte Carlo, stochastic

sampling, area light sources, fuzzy reflection, anti-aliasing

– Volume Rendering: how to render volume data? Medical Imaging, Scientific Visualization

Reflections• If only one reflected ray is considered, then ray-

tracing will only handle perfect mirrors.

Reflections• Glossy reflections (multiple reflected rays) blur

the reflection: use of Monte Carlo method

Translucency

Translucency

Example of Volume Rendering

Example of Volume Rendering

Example of Volume Rendering

Example of Volume Rendering

Available Documents

• Available : – Introduction to Computer Graphics– Deterministic Ray Tracing– Texturing– Stochastic Ray Tracing– Volume Rendering

http://www.irisa.fr/prive/kadi/Cours_LR2V/