Shading

What is Shading?

• Assigning of a color to a pixel in the final image.

• So, everything in shading is about how to select and combine colors to get the look you want.

What impacts shading?

• The lights in a scene.

• The geometry of objects in a scene.

• The normals of objects.

• The shader properties of an object:– Color,transparency, emissivity, etc…

• The rendering algorithm– Eg ray-tracing versus scan-line rendering.

The Original CG Shading Techniques

• Faceted Shading

• Smooth Shading

• Specular Shading

What is a Normal?

Plane

Normal

Light

Reflected Light

Plane

Normal Reflected Light

Eyepoint

Eyepoint

Faceted/Flat Shading

Smooth/Gouraud Shading

Specular/Phong Shading

Next: Surface Shaders

• A grouping of all variables that influence the rendered color of a 3D object.

• Surface finish

• Simulated material.

• Surface libraries/material databases.

• Surface Layers

• RenderMan Shading

Surface Layers

• Combine multiple shaders for astonishing effects.

• Build up shades like a painter.

Renderman Shaders

• Renderman is a procedural shader language with tremendous versatility.

• All major feature animated feature films use Renderman as part of production.

• Like programming in C code.

• You write Shaders for Renderman like you would write C code for computers.

Image Mapping

• Generally referred to as Texture Mapping.

• 2D Texture Mapping

• Creating the map

• Maps for real-time

• Maps for feature film

1 Map Many Attributes

1 Map Many Parts

Image Mapping in Games

Image Mapping in Film

Projection Methods

Projection Methods

Positioning the Map

Map Blending

Surface Reflectivity

• Ambient Reflection

• Diffuse Reflection

• Specular Reflection

• Reflection maps

• Environment Maps

• Glow/Incandescence

Surface Reflectivity

Reflection/Environment Maps

Color Maps

Surface Texture/Roughness

• Visual textures – like brick wallpaper.

• Spatial textures/roughness – mod geometry.

• Bump maps – modify surface normals.

• Displacement maps

• 2D Procedural `Texture’ maps.

• 3D Procedural `Texture’ maps.

Bump Map Example

2d Procedural texture maps

3D Procedural texture maps