From BlenderWiki

[edit] Diffuse Shaders

[edit] Description

A diffuse shader determines, simply speaking, the general colour of a material when light is shined on it. Most shaders that are designed to mimic reality give a smooth falloff from bright to dark from the point of the strongest illumination to the shadowed areas, but Blender also has other shaders for various special effects.

[edit] Options

All diffuse shaders have the following options:

Color

The base Diffuse color of the material

Ref

The shader's brightness, or more accurately, the amount of incident light energy that is actually diffusely reflected towards the camera.

[edit] Technical Details

Light striking a surface and then re-irradiated via a Diffusion phenomenon will be scattered, i.e., re-irradiated in all directions isotropically. This means that the camera will see the same amount of light from that surface point no matter what the incident viewing angle is. It is this quality that makes diffuse light viewpoint independent. Of course the amount of light that strikes the surface depends on the incident light angle. If most of the light striking a surface is reflected diffusely, the surface will have a matte appearance (Light re-irradiated in the diffusion phenomenon.).

[edit] Hints

Some shaders' names may sound odd - they are traditionally named after the people who invented them.

[edit] Lambert

[edit] Description

This is Blender's default diffuse shader, and is good general all-around work horse...neigh!

[edit] Options

This shader has only the default option, determining how much of available light is reflected. Default is 0.8, to allow some other objects to be brighter.

[edit] Oren-Nayar

[edit] Description

Oren-Nayar takes a somewhat more 'physical' approach to the diffusion phenomena as it takes into account the amount of microscopic roughness of the surface.

[edit] Options

Rough

The roughness of the surface, and hence, the amount of diffuse scattering

[edit] Toon

[edit] Description

The Toon shader is a very 'un-physical' shader in that it is not meant to fake reality but to produce cartoon cel styled rendering, with clear boundaries between light and shadow and uniformly lit/shadowed regions.

[edit] Options

Size

The size of the lit area

Smooth

The softness of the boundary between lit and shadowed areas

[edit] Minnaert

[edit] Description

Minnaert works by darkening parts of the standard Lambertian shader, so if Dark is 1 you get exactly the Lambertian result. Higher darkness values will darken the center of an object (where it points towards the viewer). Lower darkness values will lighten the edges of the object, making it look somewhat velvet.

[edit] Options

Dark

The darkness of the 'lit' areas (higher) or the darkness of the edges pointing away from the light source (lower).

[edit] Fresnel

[edit] Description

With a Fresnel Shader the amount of diffuse reflected light depends on the incidence angle, i.e. from the direction of the light source. Areas pointing directly towards the light source appear darker, areas perpendicular to the incoming light become brighter.

[edit] Options

Ref is the Reflectivity; amount of color reflected for each unit of light received. Fresnel is the power of the Fresnel effect, and Fac is the amount of the effect to blend in.

[edit] Other Options

If you look farther down the side of the shaders tab, you will see several other buttons.

• Cubic:

Uses cubic interpolation of diffuse values for smoother transitions (between light and dark).

• Bias:

Eliminates ray-traced shadow errors with the Phong specular shader.

Without Cubic enabled.

With Cubic enabled.

Animation switching between Non-Cubic and Cubic shadowing. You will need a modern, standards compliant, browser to see the animation. Click to View Animation.