《Lighting and Shading - 07-lighting》.pdf

Lighting and Shading Lighting and Shading Properties of Light Properties of Light Light Sources Light Sources Phong Illumination Model Phong Illumination Model Normal Vectors Normal Vectors [Angel, Ch. 6.1-6.4] [Angel, Ch. 6.1-6.4] Announcements Announcements • Written assignment # 1 due Thursday – Handin at beginning of class • Programming assignment #2 out Thursday 1 The Rendering Equation The Rendering Equation • (Angel, Ch 13) Outline Outline • Lighting models (OpenGL oriented) • Reflection models (Phong shading) • Normals • Color 2 Common Types of Light Sources Common Types of Light Sources • Ambient light: no identifiable source or direction • Point source: given only by point • Distant light: given only by direction • Spotlight: from source in direction – Cut-off angle defines a cone of light – Attenuation function (brighter in center) • Light source described by a luminance – Each color is described separately – I = [I I I ]T (I for intensity) r g b – Sometimes calculate generically (applies to r, g, b) Ambient Light Ambient Light • Intensity is the same at all points • This light does not have a direction (or .. it is the same in all directions) 3 Point Source Point Source • Given by a point p0 • Light emitted from that point equally in all directions • Intensity decreases with square of distance One Limitation of Point