Non-Photorealistic RenderingNon-Photorealistic Rendering

Mario Costa SousaMario Costa Sousa

Department of Computer ScienceDepartment of Computer Science

University of CalgaryUniversity of Calgary

Mario Costa SousaMario Costa Sousa

Department of Computer ScienceDepartment of Computer Science

University of CalgaryUniversity of Calgary

Computers: Process, Transform, Computers: Process, Transform, CommunicateCommunicate

Origin (where does information come from?)Throughput (how frequent?)Latency (how long do I have to wait)? Presentation (what does it look like?)

Information

Computers GraphicsComputers Graphics: : technology for presenting informationtechnology for presenting information

What impresses most people is the photorealistic quality of

the images

What impresses most people is the photorealistic quality of

the images

Computer Graphics:Computer Graphics:

Information transported by an image can take many

different forms

Information transported by an image can take many

different forms

Photograph of a sailboatPhotograph of a sailboat

Vast amount of information:Vast amount of information:

Time of dayTime of dayThe weatherThe weatherWind directionWind directionSpeedSpeedRelationships between boat and environmentRelationships between boat and environmentetc…etc…

HOWEVER…HOWEVER…

Little use to someone attempting to build a sailboat!Little use to someone attempting to build a sailboat!

A sailboat builder would certainly prefer:A sailboat builder would certainly prefer:Technical drawings, blueprintsTechnical drawings, blueprintsLine drawing representations of boat partsLine drawing representations of boat partsSketches of design ideasSketches of design ideas

Imagery generated by illustrators (artistic, Imagery generated by illustrators (artistic, technical, scientific) has been used to technical, scientific) has been used to provide information that may not be readily provide information that may not be readily apparent in photographs or real life.apparent in photographs or real life.

Traditionally…Traditionally…

Imagery generated by illustrators (artistic, Imagery generated by illustrators (artistic, technical, scientific) has been used to technical, scientific) has been used to provide information that may not be readily provide information that may not be readily apparent in photographs or real life.apparent in photographs or real life.

Non-Photorealistic Rendering (NPR):Non-Photorealistic Rendering (NPR):

• Apply a similar goal to computer generated-Apply a similar goal to computer generated-imagesimages

• New field of research in computer graphicsNew field of research in computer graphics

Traditionally…Traditionally…

PhotorealismPhotorealism

• Driving force behind computer graphics Driving force behind computer graphics for the past 35 yearsfor the past 35 years

• Quality of image judged by how closely Quality of image judged by how closely they resemble a photographthey resemble a photograph

• Images are rendered by running a Images are rendered by running a physics-simulation which emulates the physics-simulation which emulates the behavior of light inside the modeled behavior of light inside the modeled scenescene

• Driving force behind computer graphics Driving force behind computer graphics for the past 35 yearsfor the past 35 years

• Quality of image judged by how closely Quality of image judged by how closely they resemble a photographthey resemble a photograph

• Images are rendered by running a Images are rendered by running a physics-simulation which emulates the physics-simulation which emulates the behavior of light inside the modeled behavior of light inside the modeled scenescene

Effects needed for realismEffects needed for realism

• ShadowsShadows

• Reflections (Mirrors)Reflections (Mirrors)

• Transparency Transparency

• Interreflections

• Detail (Textures etc.)Detail (Textures etc.)

• Complex IlluminationComplex Illumination

• Realistic MaterialsRealistic Materials

• And many moreAnd many more

Non-Photorealistic Rendering (NPR)Non-Photorealistic Rendering (NPR)

• Images are judged by Images are judged by how effectively they how effectively they communicatecommunicate..

• Involves Involves stylizationstylization and and communicationcommunication, , usually driven by usually driven by human perceptionhuman perception

• Knowledge and techniques long used by Knowledge and techniques long used by artists and illustratorsartists and illustrators

• Emphasis on specific features of a scene, Emphasis on specific features of a scene, expose subtle attributes, omit extraneous expose subtle attributes, omit extraneous informationinformation

• Brings together Brings together artart and and sciencescience

• Images are judged by Images are judged by how effectively they how effectively they communicatecommunicate..

• Involves Involves stylizationstylization and and communicationcommunication, , usually driven by usually driven by human perceptionhuman perception

• Knowledge and techniques long used by Knowledge and techniques long used by artists and illustratorsartists and illustrators

• Emphasis on specific features of a scene, Emphasis on specific features of a scene, expose subtle attributes, omit extraneous expose subtle attributes, omit extraneous informationinformation

• Brings together Brings together artart and and sciencescience

Non-Photorealistic Rendering (NPR)Non-Photorealistic Rendering (NPR)

• Alternate display modelsAlternate display models

• Increase expressive power of CG Increase expressive power of CG

• Many fieldsMany fields

• CG revisitedCG revisited

• Alternate display modelsAlternate display models

• Increase expressive power of CG Increase expressive power of CG

• Many fieldsMany fields

• CG revisitedCG revisited

Recipe for Image Generation

Computer Science

MathLinear Algebra (Matrices, Vectors)Discrete representations (Images)

PhysicsLighting/Energy transferColor reflections/refraction

Mechanical EngineeringCAD/CAMSolid Models

Recipe for Image Generation

Computer Science

MathLinear Algebra (Matrices, Vectors)Discrete representations (Images)

PhysicsLighting/Energy transferColor reflections/refraction

Mechanical EngineeringCAD/CAMSolid Models

Art and IllustrationNon-Photorealistic Rendering

Applications NPR == CG&Viz!Applications NPR == CG&Viz!

• Art, Entertainment, PublishingArt, Entertainment, Publishing– Movie Production, Animation, Special EffectsMovie Production, Animation, Special Effects

– Computer GamesComputer Games

– World Wide WebWorld Wide Web

– Slide, Book, Magazine, Multimedia DesignSlide, Book, Magazine, Multimedia Design

• Science and EngineeringScience and Engineering– Computer-Aided Design (CAD)Computer-Aided Design (CAD)

– SimulationsSimulations

– Scientific Analysis and VisualizationScientific Analysis and Visualization

– Process Control and MonitoringProcess Control and Monitoring

• Art, Entertainment, PublishingArt, Entertainment, Publishing– Movie Production, Animation, Special EffectsMovie Production, Animation, Special Effects

– Computer GamesComputer Games

– World Wide WebWorld Wide Web

– Slide, Book, Magazine, Multimedia DesignSlide, Book, Magazine, Multimedia Design

• Science and EngineeringScience and Engineering– Computer-Aided Design (CAD)Computer-Aided Design (CAD)

– SimulationsSimulations

– Scientific Analysis and VisualizationScientific Analysis and Visualization

– Process Control and MonitoringProcess Control and Monitoring

Traditional Art & IllustrationTraditional Art & Illustration

• Art, Entertainment, PublishingArt, Entertainment, Publishing

– Artists, Designers, illustratorsArtists, Designers, illustrators

• Science and EngineeringScience and Engineering

– Technical IllustratorsTechnical Illustrators

– Scientific Illustrators or Scientific Illustrators or Natural Science Illustrators Natural Science Illustrators (medicine, botany, archeology, etc)(medicine, botany, archeology, etc)

• Art, Entertainment, PublishingArt, Entertainment, Publishing

– Artists, Designers, illustratorsArtists, Designers, illustrators

• Science and EngineeringScience and Engineering

– Technical IllustratorsTechnical Illustrators

– Scientific Illustrators or Scientific Illustrators or Natural Science Illustrators Natural Science Illustrators (medicine, botany, archeology, etc)(medicine, botany, archeology, etc)

Art, Entertainment, Publishing :

Movie Production, Animation, Special Effects

“What Dreams May Come”First motion picture with full NPR effects

“Tarzan”“Star Wars II”“Matrix II”…

Tools for artists, painting systems, pre-production

Art, Entertainment, Publishing :

Computer Games, Interactive Theatre

• Tools for artists• Painting systems• Pre-production• Stylized output• Real-time NPR• …

Art, Entertainment, Publishing :

WWW, Slide, Book, Magazine, Interactive Multimedia Design

Science and Engineering:Computer-Aided Design (CAD)

Mechanical EngineersMechanical EngineersLand DevelopersLand DevelopersCivil EngineersCivil EngineersLandscape ArchitectsLandscape ArchitectsArchitectsArchitectsCivil PlannersCivil Planners

Scientific Analysis and VisualizationSimulations

MedicineMedicineBotanyBotanyArcheologyArcheologyPaintingsPaintings