Having read the Blender Manual Section TEXTURES, many people still find the concepts behind the texturing system and applying textures difficult to grasp.
There are some excellent tutorials about texturing on the net. In this tutorial we will explore how to apply these concepts with the Blender texturing system. The texturing system is quite complex, and more advanced maps are normally created by combining several different textures. Also for more advanced texturing you will need to learn how to create and use UV-Maps.
This is the most basic mapping type. You can use an image or a procedural texture to change the color of a material.
1) Use an image texture as texture type. Leave everything else as it is. The button Col in the Map To Panel determines that a map is a colormap. The slide number button Col governs the blending amount of the texture, Neg inverts the colourvalues. If you use No RGB only the intensity information from the picture is used. The color is then taken from the RGB sliders in the Map To Panel.
2) It's a bit more complicated with procedural textures, because the result depends on the type of value the texture produces. If the resulttype is intensity (e.g. Clouds), the color is taken from the RGB sliders in the Map To Panel. If the resulttype is color (e.g. Magic), everything is handled as with image textures. If the resulttype is a normal value (e.g. Stucci), you don't get any color.
A Diffusemap changes the parameter Ref, i.e. the amount of light a surface reflects with diffuse reflection.
To understand the effect of this and all other mappings, we have to discuss the meaning of the NumButton DVar (Destination Value). White in a texture will be mapped to the value of the DVar Button. So if you set Dvar to 1, white will be mapped to 1, if you set DVar to 0, white will be mapped to 0. The result is multiplied with the value of the Var number button. Black on the other hand does not change anything, so the settings from the material will stay unchanged. The difference between the material settings and the DVar button is the range for the texture. Let's take a look at an example.
If we use the default settings for the Diffusemap the range of the values is small, the Ref Value is changed between 0.8 (black pixels in the texture) and 1.0 (white pixels in the texture). The range is 1.0 - 0.8 = 0.2.
When we change the Ref parameter in the Shaders panel to 0, we'll get a much larger range of Ref values from 0.0 (black pixels in the texture) to 1.0 (white pixels in the texture).
There is another way to get a large range. Many of the Map To buttons have three states, Off/On/Inverted. Set Ref to "Inverted" (click it twice, it will be painted in yellow), DVar to 0 and Ref in the Shaders panel to 1.
Why is this so complex?
Well, with complexity comes flexibility. You can use an image (or procedural texture) for a few mappings at once, e.g. Color, Diffuse, Alpha, Spec and the like.
Luminosity is the property of self-illumination, i.e. of objects emitting light. So the parameter to change with the texture is Emit. This light does not illuminate other objects - you would have to use Global Illumination (Yafray) to use an emitting object as a true light source. Radiosity rendering does not work with Luminositymaps.
Everything that was said about the DVar value applies here exactly as with Diffusemaps.
This is the second most important material attribute. Specularity fakes the reflections of light sources. Of course you can modify the general specularity with a texture. In Blender you can change three different attributes related to specularity:
- Spec: The degree of specularity. You can't set values above 1.0 with Specularitymaps, but you could invert the texture and set Spec on the Shaders panel to a higher value and Dvar to the lowest value of your range. So the texture actually lowers the specularity in all areas, that should have a low specularity.
- Hard: The hardness of the specular reflections. Sometimes called "Glossiness". A DVar of 1 is equivalent to a hardness of 130. Use the same method as described above to achieve a greater range for the hardness.
- Csp: The specularity color.
You will probably use some kind of "Dirtmapping" (stenciling) to change the specularity in certain regions of an object, like an often touched object, that is shinier on the used or touched parts.
A Reflectionmap would be used to fake real raytracing reflections, either because you don't want to use raytracing, or you don't want to create a scene, or you need a special effect you don't get with raytraced reflections (like blurred reflections). A Reflectionmap would be a Colormap, typically an Environment Map. Since you can use prerendered Environment Maps, you can fake a surrounding for your object. Sometimes it is sufficient to use a simple Colormap that just bears the right colours, e.g. if you want to create a stormy sea it is not necessary that the clouds above are truly reflected in the water.
Environment Maps are a bit more complicated to create, see the respective section in the manual.
A very different kind of texture would be used to change the amount of raytracing reflections, the RayMir value. This is usefull for something like a stained or dirty mirror. Simply click the RayMir button in the Map To panel and lower the DVar.
Transparency- or Alphamaps change the (partial) visibility of an object. They don't have to be transparent themselves (though it doesn't hurt, see Use Alpha for Object Transparency). You will often use an image as Colormap and Transparencymap together. A nice example for a Transparencymap is in the paragraph Translucencymap.
There's one catch though, you can't change Fresnel transparency with a Transparencymap. So you have to use plain transparency, or fake the Fresnel effect with the method described in the section Map Input. The importance of the DVar Value is here especially evident. The texture increases the Alpha value of the material. But of course one could use it just the other way round. Then you would have to set the Alpha value in the Material panel to 1, and the DVar to 0.
Well, there's no such thing as a Refractionmap. You can't change the IOR with a texture. You may try and use Environment Maps to fake refraction (see Tutorials/Solid and Hollow Glass), but the result is often not worth the effort (for stills, in an animation it might not be that noticeable).
Translucency is a material property of all semitransparent materials, like frosted glass, paper, plastic, cloth, skin, stained glass and the like. It allows objects to be lit from behind.
Totally clear glass does not show where the lightrays travel through it. But if the glass is dirty or uneven you will see the path of the light. In the first example (Translucency 1) the glass material has a transparency of about 0.5 and a translucency of 0.78. So the glass is brighter where the light rays hit the surface from behind. Additionally a Transparencymap - which sets Alpha to 1 - lets the surface appear to be stained. If we use the same map also as a Translucencymap (Translucency 2), the stain appears to be lit - which it would be of course also in reality.
The settings for the material (Z-Transp, but ray tracing shadows):
The texture itself is a Hard Noise Clouds texture, with modified Brightness and Contrast.
Bumpmaps are very usefull to create the illusion of geometry. Something like a canvas or any small structures are either difficult to model, or the number of vertices would become much to high. As long as you don't get too close with the camera you wont notice the difference.
A typical Bumpmap would be a greyscale image applied to Nor in the Map To Panel. The Nor slider sets the depth of the bumping.
If you want to know more about bumpmapping, see the respective section in the manual (Bump and Normal Maps).
Now I will try to explain what a Dirtmap is and how you create one. There are many different things that people mean when they talk about dirtmapping. Sometimes a Diffusemap is meant. Dirtshading on the other hand is often used for Ambient Occlusion.
With a Dirtmap I simply mean any texture, that breaks the clean, uniform, untouched look of image or procedural textures. You may do this by simply combining some partially transparent textures resp. textures that affect only parts of the picture in a semirandom way. You can also select parts of the object with a Stencil texture. And of course you can (and will) combine both of these methods.
As long as two textures doesn't affect the same property you can simply apply one after the other. To select only parts of your texture to apply another texture with the same properties use stenciling. Or use it as an convenient method to separate two different sections on your texture.
You need at least three textures for this.
- The basic texture (e.g. color).
- The selecting (stenciling) texture.
- The Dirtmap affecting the same or other properties then the first texture.
Be aware of the fact that the stenciling texture has to be an intensity texture, so if you want to use an image (or other RGB) texture you must click No RGB.
The image texture used as a dirtmap for our example contains some semirandom noise.
Nor for the stenciling texture was not really necessary, but it adds a nice 3D effect. Since the stenciling texture is mostly white, I had to use Neg to use the black pixels as mask.
The third texture ("Dirt") affects Col, Nor and Spec.
Use UV Coordinates for your Maps
It is often necessary to create UV coordinates for more complicated textures/objects. Remember, UV coordinates only describe the geometry of the mapping, i.e. which pixels to map on what face. You can use the UV coordinates to create any mapping you want.
- Create an UV map for your object. This is beyond the scope of this tutorial, see the section UV Mapping in the manual.
- Don't turn TexFace in the Material Panel in the Material buttons (F5) on.
- Load the image you used tor UV-mapping (or any image with the same size) as an image texture. Change Map Input to UV.
- Now you can use this image - or multiple different images - for your maps, including colormapping.
The advantage of this technique is that you have much better control over your texture. Even if you just want to texture something like a cube shaped object, you're often better off with UV mapped textures.