What is NPR? Amy Gooch Amy Gooch Amy Gooch Define Photorealistic - PDF document

What is NPR? Amy Gooch Amy Gooch Amy Gooch Define Photorealistic Rendering Photo: Photo: Photo: • Comes from the Greek Comes from the Greek phos phos , meaning light , meaning light • • Comes from the Greek phos , meaning light or produced by light or produced by light or produced by light Page ‹#›

Define Photorealistic Rendering Realistic: Realistic: Realistic: • Dictionary definition: Dictionary definition: • • Dictionary definition: – fidelity in art and literature to nature or to – fidelity in art and literature to nature or to – fidelity in art and literature to nature or to real life and to accurate representation real life and to accurate representation real life and to accurate representation without idealization without idealization without idealization Rendering: Rendering: Rendering: • Convert a representation of a virtual scene Convert a representation of a virtual scene • • Convert a representation of a virtual scene into an image for viewing into an image for viewing into an image for viewing Understand Photorealistic Rendering • Light, material properties, reflections & Light, material properties, reflections & • • Light, material properties, reflections & refraction refraction refraction • • Radiosity Radiosity, ray tracing, & image-based , ray tracing, & image-based • Radiosity, ray tracing, & image-based rendering rendering rendering Page ‹#›

Example: Art of Jan Vermeer Example: Photorealistic Rendering From From Lightscape Lightscape From Lightscape Page ‹#›

Define Non-Photorealistic Rendering Descriptors: Descriptors: Descriptors: • expressive expressive • • expressive • • artistic artistic • artistic • • painterly painterly • painterly • • interpretative interpretative • interpretative Approach Photorealistic rendering: Photorealistic rendering: Photorealistic rendering: • Simulation, usually physically based Simulation, usually physically based • • Simulation, usually physically based Non-photorealistic rendering: Non-photorealistic rendering: Non-photorealistic rendering: • Stylization, driven by human perception Stylization, driven by human perception • • Stylization, driven by human perception • • Brings together art and science Brings together art and science • Brings together art and science • Concentrates less on the process and more Concentrates less on the process and more • • Concentrates less on the process and more on the results on the results on the results Page ‹#›

Characteristic Photorealistic rendering: Photorealistic rendering: Photorealistic rendering: • Objective Objective • • Objective Non-photorealistic rendering: Non-photorealistic rendering: Non-photorealistic rendering: • Subjective Subjective • • Subjective Influences Photorealistic rendering: Photorealistic rendering: Photorealistic rendering: • Simulation of physical processes Simulation of physical processes • • Simulation of physical processes Non-photorealistic rendering: Non-photorealistic rendering: Non-photorealistic rendering: • Artistic processes Artistic processes • • Artistic processes • Perceptual-based • Perceptual-based • Perceptual-based Page ‹#›

Level of detail Photorealistic rendering: Photorealistic rendering: Photorealistic rendering: • High level of detail, hard to neglect detail High level of detail, hard to neglect detail • • High level of detail, hard to neglect detail Non-photorealistic rendering: Non-photorealistic rendering: Non-photorealistic rendering: • Runs the range Runs the range • • Runs the range • • Adapt level of detail across the image to Adapt level of detail across the image to • Adapt level of detail across the image to focus the viewers attention focus the viewers attention focus the viewers attention Level of Abstraction From Understanding Comics, by Scott McCloud From Understanding Comics, by Scott McCloud, 1993 , 1993 From Understanding Comics, by Scott McCloud, 1993 Page ‹#›

Illustrators Use of Lines From Technical Illustration From Technical Illustration by Judy Martin by Judy Martin From Technical Illustration by Judy Martin Wire frame versus Edge Lines Are Real Edges Sufficient For Object Recognition? Are Real Edges Sufficient For Object Recognition? Sanocki et al. Sanocki et al. Page ‹#›

Silhouettes Submitted to The Journal of Graphics Tools: Submitted to The Journal of Graphics Tools: Evaluating Silhouette Algorithms for Polygonal Models, Hartner et al. Evaluating Silhouette Algorithms for Polygonal Models, Hartner et al. A Top-Down Approach to Normal Cone Hierarchies, Hartner et al. A Top-Down Approach to Normal Cone Hierarchies, Hartner et al. Evaluating Object Space Methods for Silhouette Rendering, Beddes et al. Evaluating Object Space Methods for Silhouette Rendering, Beddes et al. Creases Page ‹#›

Surface boundaries Silhouettes in Black, Creases in White Gooch et al., I3D 1999 Gooch et al., I3D 1999 Gooch et al., I3D 1999 Page ‹#›

Artistic Silhouettes Gooch et al., I3D 1999 I3D 1999 Gooch et al., Gooch et al., I3D 1999 Shading Used by Artists Complementary Shading Complementary Shading Final image Final image Complementary Shading Final image The Book of Color, by Jose Parramon, 1993 The Book of Color, by Jose Parramon, 1993 The Book of Color, by Jose Parramon, 1993 Page ‹#›

Tone Shading on a Gray Model Tone Shading Phong Shading Phong Shading Phong Shading Tone Shading Tone Shading Tone Shading Gooch et al., ACM Siggraph 1998 ACM Siggraph 1998 Gooch et al., Gooch et al., ACM Siggraph 1998 Page ‹#›

Treasure Planet Material Properties Illustration Illustration Illustration Photograph Photograph Photograph Page ‹#›

Imitating Material Properties Phong shaded Metal shaded Phong shaded Phong shaded Metal shaded Metal shaded Illustrators Use of Shadows Page ‹#›

Soft Colored Shadow Gooch et al., Gooch et al., ACM I3D 1999 ACM I3D 1999 Mayan Temple Example Potter et al. Potter et al. Potter et al. Page ‹#›

Motivation for Computer Scientists Provide tools for : Provide tools for : Provide tools for : • artists artists • • artists • non-artists • non-artists • non-artists Categorizing NPR Hard to categorize NPR Hard to categorize NPR Hard to categorize NPR • Natural media emulation Natural media emulation • • Natural media emulation – pen-an-ink – pen-an-ink – pen-an-ink – watercolor watercolor – – watercolor Winkenbach et al. et al. 1994 Winkenbach Winkenbach et al. 1994 1994 – – oil oil – oil Curtis et al. 1997 Hertzmann 1997 Hertzmann Curtis et al. Curtis et al. 1997 Hertzmann 1997 1997 1997 Page ‹#›

Line and Stipple Drawing Secord et al. 2002 et al. 2002 Secord Secord et al. 2002 Deussen et al. Deussen et al. Deussen et al. Way et al. 2002 Way et al. 2002 Way et al. 2002 Sousa et al. 2003 Sousa et al. 2003 Sousa et al. 2003 Hatching Webb et al. 2002 Webb et al. 2002 Webb et al. 2002 Hertzmann Hertzmann 2000 2000 Hertzmann 2000 Praun et al. 2001 et al. 2001 Praun Praun et al. 2001 Page ‹#›

Cartoon Rendering Markosian Markosian et al. et al. Markosian et al. Kaplan et al. Kaplan et al. Kaplan et al. Lake et al. Lake et al. Lake et al. Simulating materials Rudolf et al. 2003 Rudolf et al. 2003 Rudolf et al. 2003 Wax Crayons, Rudolf et al. 2003 Wax Crayons, Rudolf et al. 2003 Wax Crayons, Rudolf et al. 2003 Page ‹#›

Embossing Sourin 2001 Sourin 2001 Sourin 2001 Categorizing NPR • Image and video enhancement Image and video enhancement • • Image and video enhancement Before After Before Before After After From www.revisionfx revisionfx.com .com From www. From www.revisionfx.com Page ‹#›

Categorizing NPR • • Image and video enhancement Image and video enhancement • Image and video enhancement From www.revisionfx From www. revisionfx.com .com From www.revisionfx.com Categorizing NPR • User interface, like a paint program (2D & 3D) User interface, like a paint program (2D & 3D) • • User interface, like a paint program (2D & 3D) Haeberli Haeberli 1990 1990 Haeberli 1990 Cohen 2000 Cohen 2000 Cohen 2000 Gooch et al. 2002 Gooch et al. 2002 Gooch et al. 2002 Salisbury et al. 1997 Salisbury et al. 1997 Salisbury et al. 1997 Page ‹#›

Categorizing NPR • • Process applied to geometric models Process applied to geometric models • Process applied to geometric models Meier 1996 Meier Meier 1996 1996 Saito et al. 1990 Dooley et al. 1990 Saito et al. Saito et al. 1990 Dooley et al. Dooley et al. 1990 1990 1990 Categorizing NPR • Process applied to geometric models Process applied to geometric models • • Process applied to geometric models Gooch et al. 1998 Gooch et al. 1998 Gooch et al. 1998 Page ‹#›