This article will explain you two super important concepts - textures and UV mapping, so make sure you read this carefully! :)
Textures (also called texture maps or just maps) are images we “stick” on our 3D models to make them more realistic.
Most of the stuff around us does not have flat color finish. Instead, real-world objects have a great variety of finishes, from grainy woods to the rough stones. Let’s consider the difference between two rendered views, one without the use of textures and the one with the textures:
Texture maps are property of materials, and each material can have more than one texture, that each define different aspect of its appearance.
If you take a look at the Rhino material, below Basic Settings, we have a list of properties called “Textures”.
Now let’s quickly consider what each of these do:
Color texture (also called “diffuse”) is what affects the look of the material the most. It defines the main color or pattern of the object, such as browny tiles of the wooden floor, or the red/white patterns of the brick, as seen above.
Transparency texture does not define the color of the material but -as name suggests- its transparency. These are grayscale images that work like this: the darker the pixel on the texture is, the more transparent material will be at that point. Consequently, white pixels are totally opaque, while black pixels are totally transparent.
Transparency texture allow us to achieve complex effects without having to do much modelling – see above example of a black/white wire mesh image used as transparency texture on a simple cylinder.
Bump textures are grayscale images that give “3D effect” of bumps and wrinkles on the surface of the object. The brighter the pixel is, the more that part of the surface will appear to “stick out” and vice versa – dark pixels will make effect of hole and gaps punched into the surface.
Here’s an example of the same rendering of the brick wall without and with the use of bump map, notice how the bump map gives more richness and roughness to material:
Finally, here is how color map and bump map for this brick material look like and how they are applied together:
We will skip Environment texture for now – so these are the texture types that Rhino material allows for. Please note that more advanced program (or rendering plugins) offer much more texture types to provide more visual fidelity. But for a starter, we can make pretty good images just by using these 3 texture types.
Before we jump into tutorial, there is one very important concept to introduce first:
So we said that textures are images that we “stick” (or “project”) to our 3D objects to make them look realistic, but there are many ways that the texture image can be applied to the object. Consider the following examples:
As you can obviously see, we applied the very same map in different way to this box representing a wall, and obviously the size of the image and direction play a crucial role in making it look realistic (or even logical).
UV Mapping (or just mapping) is a process of defining how the texture map will fit the object: the size and direction (rotation) of the fit.
After covering the basic terms, check the following tutorial to learn how we actually use textures in Rhino:
1C-2 : Using Textured Materials In RhinoHere's how to use textured materials in Rhino.