UV Mapping

After a 3D object has been modeled it must be prepared for texturing. 3D surfaces can be “unwrapped” into a 2D representation with . This process is generally done by either the modelers before the geometry is sent to texturing or by a texturing artist before texturing can begin. It is particularly useful to know what the final object will look like before laying out UV’s. If and object is just going to be a solid color then the UV’s can be rough, but if the object is going to have extremely detailed textures, then a thorough UV set has to be laid out before texturing can begin.

Materials/Texturing

Once a UV set is laid out for a model, materials can be applied to the surface. This process can involve painting texture maps or using procedural shaders to define surface properties. Texture artists have to pay close attention to the surface properties of the object they are texturing in order for the object to accurately interact with the cg lighting.

Ambient Color

Ambient color simulates the effect of base illumination without a light source. If there are no lights in a scene, the ambient color attribute of a material shader can create illumination. A higher ambient color value can flatten a surface because it is adding illumination to all areas including parts of the geometry that are in shadow.

Diffuse

The diffuse value of a material shader determines how much light is absorbed by the material. Diffuse can be thought of as how “responsive” a material is to the lights in the environment. Metals generally have low diffuse values because they rely on reflections and specular attributes for illumination. Pure reflective surfaces like mirror have a diffuse value of zero.

ColorColor is an RGB value that is used during lighting calculation. The saturation of the color attribute of a surface shader determines how much of the base color of a surface interacts with color lights.

Specularity

Specularity is a term that is used to describe the shininess of a surface. A specular highlight is the very bright spot of a shiny surface where light is perfectly reflected. Specular highlights are often used by lighting artist to enhance the shape of geometry

Shader Type

• Lambert

• Phong

• Phong E

• Blinn

• Anisotropic

• Use Background

Lambert

Lambert surfaces have no specularity or reflectivity. They are often used for matte surfaces without reflectivity. A Lambert surface diffuses and scatters light evenly across the surface.

The phong shader type was the first shader with specular highlights and reflectivity. They are often used for glossy objects like plastics and glass. The phong material has a adjustable sharp specular highlight

Phong

Blinn

The Blinn shader type has a specular highlight with more control than a Phong. A Blinn surface creates a specular highlight that diffuses more gradually than a Phong. Blinn surface shaders are often used for shiny surfaces like metals.

A Phong E is an expanded version of the Phong surface material that creates a specular highlight that drops off more gradually that a Phong, yet sharper than a Blinn. Phong E shades are often used to create metallic surfaces due to the fact that that offer greater control over specular highlights than a Phong or Blinn.

Phong E

Anisotropic

Anisotropy (the opposite of isotropy) is defined as the property of being directionally dependent. The specular highlight of an anisotropic surface material is different depending on your viewing angle. Anisotropic shaders are often used for brushed metal surfaces.

A Use Background shader is a used to “knock out” or occlude one object from another. They are often used for compositing computer generated images into live action plates in order to create integration

Use Background

Bump Maps

Bump maps are used to added texture to surface materials. A Bump map creates the appearance of surface deformation by altering the direction of surface normals without actually deforming the surface. A Bump map modifies the direction of a surface normal during lighting calculations.

Displacement Maps

A displacement map is similar to a bump map in the sense that it uses a texture to create surface deformation, but a displacement map is applied directly to the geometry rather than being applied to the shader like a bump map.

Transparency

The higher the transparency the more “see-through” an object becomes. A value of 1 or color of white is fully transparent. A value of zero or color of black is fully opaque. Generally transparency is represented as a black to white gradient.