a very brief overview of non-photorealistic rendering

A Very Brief Overview of Non-Photorealistic Rendering

Conrad Albrecht-BuehlerGraduate Thesis SeminarSeptember 24, 2001

What is Non-Photorealistic Rendering (NPR)?

Rendering of an image to mimic media other than a photographGooch: provide info not readily apparent in a photo

NPR’s Usefulness

New Artistic ToolsCan provide more useful information than a photo mightLends attractiveness to visualizationsNew modes of visualization

NPR Applications

Artist ToolArchitectureCinemaGamesScientific VisualizationCartography

Types of NPR

Image Space Effects

Perspective Space Effects

Data Mapped Visualization

Image Space Effects

Techniques applied to an output image

Style “filters” mimic a familiar artistic style by modifying the pixel image

Some work has been done in automatic media generation based on an imput image, e.g. watercolor

From Teece

From Teece

From Curtis et al.

Perspective Space Effects

Techniques applied on input models Much work has been done recreating artistic

styles using 3D models as subjects Toon Shaders typically highlight silhouettes

based on the model Technical and Architectural sketch renderings

are created from models as well

From Teece

From Teece

From Teece

From Buchanan and Sousa

From Teece

Data Mapped

Techniques applied to input data and mapped to variables Cartography Scientific Visualization

From Agrawala and Stolte

From Healey

Implementing NPR techniques

Pencil and Paper

NPR for gaming Toon rendering in real-time NPR Quake

Pencil and Paper Rendering

Simulating the interaction of paper, pencil lead, eraser, and blender based on an observational model

From Buchanan and Sousa

From Buchanan and Sousa

From Buchanan and Sousa

From Buchanan and Sousa

Cartoon Rendering

Most cartoon rendering involves heavy, dark outlines and flat shading.Some work has been done in stylized cartoon rendering such as Dr. Suess

From Kawalski

From Sega’s Fur Fighters

Creating that Toon Look

The silhouette is the edge between a front and back facing polygonFor every front facing polygon XOR in 1 into the F fieldFor every back facing polygon XOR in 1 into the B field

The Vertex Hash Table

Vertex

VFB VFB VFB VFB

1 200 300 400 500

2 300 500 X00 X00

3 400 500 X00 X00

4 500 X00 X00 X00

5 X00 X00 X00 x00From Buchanan and Sousa

The Vertex Hash Table

Vertex

VFB VFB VFB VFB

1 210 310

400 500

2 310 500 X00 X00

3 400 500 X00 X00

4 500 X00 X00 X00

5 X00 X00 X00 x00From Buchanan and Sousa

P[1,2,3]

The Vertex Hash Table

Vertex

VFB VFB VFB VFB

1 210 300

410

500

2 310 500 X00 X00

3 410 500 X00 X00

4 500 X00 X00 X00

5 X00 X00 X00 x00From Buchanan and Sousa

P[1,3,4]

The Vertex Hash Table

Vertex

VFB VFB VFB VFB

1 210 300 410 500

2 310 500 X00 X00

3 411 501

X00 X00

4 501 X00 X00 X00

5 X00 X00 X00 x00From Buchanan and Sousa

P[3,4,5]

The Vertex Hash Table

Vertex

VFB VFB VFB VFB

1 211 300 411

500

2 311 500 X00 X00

3 411 500 X00 X00

4 500 X00 X00 X00

5 X00 X00 X00 x00From Buchanan and Sousa

Silhouette={(1,2),(2,3),(3,4),(1,4)}

Note: (3,1) would not be drawn

NPR Quake

Intercept OpenGL calls so that the rendering style can be implemented independent of the game engine