Tutorial: Materials - Part 1

Together with the texture of a body the material is a main factor for the creation of realistic scenes within Blender. There are quite a few options to create effects and materials within this programme.

1. The surface:

Within the shading context, there are a number of parameters at the Material Buttons, that should be explained briefly now:

Colors:

Colors can be created in Blender with 2 systems. One is the RGB System (meaning the primary colors red, green and blue), the other on is called HSV System (meaning Hue, Saturation and Value). Within the material panel you can switch the material buttons between those systems.
In these Systems the you can selelct figures between 0.0 and 1.0. For example:

Just try to experiment with those figures to become familiar with the color mixing.

If you select the button Color a window with all color mixtures opens. There you can select the desired color by clicking the left mouse button on the specific point of the color window. With the button Sample the color can be finally selected.

Beside you have the option for selecting Hexadezimalcolorcodes, which are also used for HTML pages. Therefor you have to click the button Hex:.

With the button Spe you can adjust highlights with the color controllers. For example if you want to create a metalic object it is recommendable to adjust the color of the highlight divergent to the actuell color of the material.

With the button Mir the produced color is created by reflected light (=specula light).

Diffused Lightreflexions:

To create a realistic impression it is also important to consider how a material reflects light. In graphic design the interaction of texture, material and light is called Shader.

You will find the Shader-Panel at the material buttons, consisting of two adjusters: Ref and the related adjusters Spec and Hard.

Ref determines the amount of light, reflected by the texture, whereas Spec determines the intensity of the highlights.

There are 6 different types of diffused shaders in Blender:

Lambert: The only parameter for its adjustment is Ref

Oren-Nayar: This shader offers besides the Ref parameter also a Rough parameter dertermining a soft light distribution.

Toon: This is a shader mainly used for material needed to create a cartoon look. It consists of two shaders, for selecting the Size of the illuminated area and for defining the acuity of the borders of the shadow (=Smooth)

Minnaert: similar to the Lambert-parameter but consists aditionally of the Dark parameter. This creates a velvetly texture, if the figures of this parametern are above 1.0. In that case surfaces appeare dimmed in the direct view. If the dark parameter is below 1.0 the surfaces are brightened and the material appears more of the metallic type.

Fresnel: If light impinges on a surface in a flat angle, it will be brightened by the

Fresnel shader. This effect can be selected with the parameter Fresnel, the intensity of the effect by Fac.

Tangent-Option: This optionapplies to all shaders. It is particularly suitable if you want to brushed material, or e.g. the bottom side of a CD. For this option UV coordinants for the Mesh have to exist.

Highlights on objects are basically approximations for mirroring of a bright light source on objects. This kind of reflections hardly ever assume an objective shape, but can be realistically emulated by different types of shaders, without really calculating a mirroring. This shaders are called Specularity-Shader.

The main parameters are figures, which modulate intensity and size of the highlights.

5 types of Specularity Shaders in Blender:

CookTorr: This is a shader with 2 parameters: Spec modulates the intensity of the highlight; Hard modulates the sharpness and the size.

Phong: This consists of the same parameters as Cook Torr, differs just in the algorithm.

Blinn: Matches with the diffuse shader Oren-Nayar. This can be idealy completed with the parameter Ref for creating realistic highlights.

Toon: Matches with the Toon-Diffuse-Shader. By using this shader, you can create smooth and stridently severed highlights.

WardIso: (=Ward Isotropic Gaussian Specular Shader) This shader uses the parameter rms instead of Hard. Small values of this parameter create small but also stridently severed highlights.

The ajduster Emit states, how strong a material itself should shine. Here the material itself shines, and no other light sources casts light on it.

To experiment with such a material you can load the scene Material/Material100.blend. In this scene you can create material for the monkey head (mascot of Blender). Select the monkeyhead – create within the material buttons F5 with the button Add New at the Links and Pipeline-Panel a new material.

All options mentioned before can be tested and rendered on this monkey head. It helps at the beginning if you select extreme values in order to recognize the differences better.

It is quite a helpful tool for the comparison of before and after pictures if you switch rendered pictures with J in the render window.

2.Texture

Usually there are hardly any surfaces with a real smooth and plain-colored surface. So the parameters mentioned above won't be enough to create real realistic impressions. Therefor 3D grahic uses textures which enable you to simulate complex colorings of surfaces and materials.

Blender offers 3 different types of textures which can be also combined:

Intensity Texture: This value determines the intensity of parameters of the surface such

as glance, transperency or different features of reflections.

RGB Texture: This value determines the chrominance.

Bump Texture: This value can be used to simulate structures of a surface without

modeling the structures before.

2.1 How to add the texture to the material?

Again, take the monkeyhead from Material/Material100.blend as an example to create a texture. Try to add a material to the object and color it by using the color parameters.

• Select the object and then select the icon for Texture Buttonsor press F6

• Within the Texture-Panel by clicking Add New a new texture will be created.

• Choose the texture typ Marble, by clicking the menu button Texture Type.

• It is advisable to choose a meaningful name for the texture or by clicking the Auto icon in the header of the Texture Buttons so that Blender accomplishes this automatically. But remember, the more complex your work will be, the more important is it to name objects and certain steps to keep an overview over the whole process.

• A testrendering will now show you a purple marbled monkey head. The basic color is, as preset before.

• In the Material-Button F5 you will have - on the right side of the window – the option to modify the color of the Marble Textur within the Map To panel.

Literatur:

Carsten Wartmann (2007), Das Blender Buch. 3D Grafik und Animation mit freier Software. Heidelberg:Dpunkt.