Basic principles of materials

From TOI-Pedia

Shader attributes

Once the shader is created the properties of the shader can be altered. To view the the properties of the shader and get an idea what can be altered the Attribute editor has to be opened by dubble clicking on the shader or select the shader and press CRTL-A. In the Attribute editor we can see the name of the shader an its properties. In this case the attribute editor is used to further define the material. The hypershade menu is best left open.

Adjusting the properties of the Shader

There are a range of properties which can be adjusted. Like the shaders not all the options have to be adjusted to generate the majority of the materials. There are two main parts of the material property which almost always have to be adjusted.

  • The first is the Common Material Attributes- This menu is independent of the type of shader used. It will contain the color and transparency information of the shader.
  • The second is the Specular Shading.- This menu will contain the information of the material on how it reacts to light. The shininess of the material simulates the smoothness of the surface of the material and will define the highlight on the object and the reflection on the object. These settings and therefore the appearance of the materials are closely related to the position , amount and strength of the light sources in the scene.

Hypershade materialenPR3.jpg

Common Material Attributes

Not all of the shader properties have to be altered. The main properties which have to be adjusted, depending on the material properties, are limited to the:

  • Color – the color of the material
  • Transparancy – the transparency of the material
  • Bump - small indentations in the object like the seams between the bricks. The bump is a fast method of simulation depth on an object without actually modeling it. This will save time but also reduces complexity of the model. A good example is a brick wall. To create the effect of the indentation of the mortar between the bricks a bump map can be used. The alternative would be to model all the bricks separately, which is not done in any case !

Hypershade materialenPR4.jpg

Specular Shading

The Specular shading properties are depending on the type of shader which is used. These settings are crucial for a realistic appearance of the material. They will have to be adjusted every time. The effect of the settings can be viewed in the small icon at the top of the Attribute Editor. There are two main sets of properties which have to be adjusted.

  • The first are the settings of the shininess of the materials. A simple rule of thumb is the smoother the material the sharper the highlight.The more microscopic scratches on the material the duller the highlight.
  • The second settings which always have to be checked is the reflectivity of the material. The default value is 0.5. This value is for most of the materials to high and have to be adjusted.

To use reflection the option of raytracing has to be activated in the render menu if the software render engine is used, if Mental Ray is used no additional settings have to be adjusted. Standard reflecting amount of materials other then Lambert and Ansiotropic is set on 0.5. The amount of reflection is based on the material properties like type and smoothness.

  • A mirror 0.9
  • Glass 0.3
  • Shiny plastic 0.4
  • Shiny floor 0.1
  • Shiny metal 0.2
  • Brick 0

Hypershade materialenPR5.jpg

There are three different options to alter the setting of the property. (From left to right)

  • A color or value can be selected and altered – if clicked on the color swatch a menu opens where a color can be selected.
  • The value of the color or the value itself can be altered by moving the slider.
  • A texture can be added. A texture is an image, like a digital photo or an image generated by Maya itself. If the checker is clicked a menu opens where a texture can be selected and added.

Hypershade materialenPR6.jpg

Note: The Specular Shading settings always have to be adjusted. The default value of the reflection of a new shader (not a Lambert)is 0.5 and is in most cases much to high.
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