Unit 4: Shading

• Shading in CG is computing the pixels colors
• It is very much about lighting

Shading and Lighting

• Given the surface normal is and the light direction vector is

• By rotating the surface, we will have the angle and which we can use to calculate the light intensity

Lambertian (Diffuse) Material

• This way, we can model a relation between the light intensity and the surface color property given that is the original surface color

• By adding another factor which represents the amount of light coming from the light source, we can have a full formula to calculate the pixel color and it is called Lambertian (Diffuse) Material

Phong Specular Reflections

• Reflections viewing depends on the viewer direction

• It is one of specular reflection models

• Given the perfect reflection direction vector and the viewer direction vector

• Properties:
• Material props:
• the specular reflection color
• the shininess of the material (opacity of shininess)
• the light intensity

• The phong material model is defined according to the formula

• The formula of the perfect reflection direction

Phong Material Model

• It’s defined by combining Lambertian (Diffuse) Material model and Phong Specular Reflections

• When we want to implement it, we should consider eliminating the negative values of cosine. So finally it becomes:

Resources

Texture Resource Guide - andrew letourneau

The Texture Resource Guide is a book that I put together that aims at consolidating a lot of information about making materials for 3D models. As I taught myself these skills and concepts I found it difficult to find a unified source of information to learn from.

https://www.letourneaudesign.com/texture-guidebook

Introduction to Shading

Keywords: shading, light, shadow, diffuse, mirror, reflection, refraction, transmission, index of refraction, Snell's law, reflection law, Fresnel equation, inverse-square law, square falloff, distant light, spherical light, point light, distant light, sun, shadow, shadow acne, acne, shadow map, Lambert cosine law, albedo, texturing, procedural texturing, aliasing, anti-aliasing, texture coordinates, checkerboard pattern, specular reflection, glossy reflection, roughness, dielectric, conductor, delta light, area light, shadow ray, shadow bias, differential area, diffuse BRDF, normal, facing ratio, smooth shading, Gouraud shading, physically based rendering, photorealistic rendering, direct illumination, indirect illumination, view dependent, view independent.

https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-shading

www.youtube.com

Interactive Computer Graphics. School of Computing, University of Utah. Full Playlist: https://www.youtube.com/playlist?list=PLplnkTzzqsZS3R5DjmCQsqupu43oS9CFN Course website: https://graphics.cs.utah.edu/courses/cs6610/spring2021/

https://www.youtube.com/watch?v=esC1HnyD9Bk