3D Materials and Textures

3D Bedroom Scene Without Materials and Textures

3D Bedroom Scene Without Materials and Textures

Following on from our previous articles on the basics of 3D Modelling and the basics of 3D lighting we now continue on to look at the basics of 3D Materials and Textures.

In 3D graphics, materials and textures are nearly as important as shapes. Imagine how boring and fake scenes would be if all the objects were grey. The material system in your chosen 3D software will allow you to model a wide variety of materials and how they each interact with light. "Light? How does that effect how an object looks?" you ask, and "didn't we already cover that?".

Well it's not just the light but rather how the material interacts with the light. You see, a material defines the optical properties of an object, its color, opacity, whether it is dull or shiny and more besides by deciding things like how much light is absorbed or reflected by the object. So what does a texture do then?

A texture is a pattern that breaks up the uniform appearance of the material. Very few objects in the real world have completely uniform surfaces. Instead most of them have patterning or variation in color: consider the grain in a piece of wood or the pile in a carpet or the mortar in a brick wall. Ok, so that the basics of 3D Materials and Textures, now let's look at them in more detail.

Materials:

Materials are applied to 3D models and they have a huge effect on how the final 3D model will look like. Materials can have a wide array of properties and it is the combination of all of these things that define the way a material looks, and how objects using that material will appear when rendered. Remember that the appearance of your materials are affected by the way that they are rendered, and by the rendering engine used (some 3D softwares have multiple render engines built in).

Materials have many surface characteristics which are used, often together, to define the final look of the model. These characteristics include...

Color

Surface colour, often also referred to as the diffuse shader is the basic flat colour of the material. When other properties are added or edited this colour will be the underlying colour that comes through. For example a material may have a high transparency value to mimic glass but the colour of the glass is decided by the diffuse shader.

3D sphere with flat surface colour

Transparency

Transparency, often called Opacity, allows other objects to be seen through the object being edited. The object still remains solid but this material setting allows more light to pass through it than is reflected thus making it "see through". Representing glass is a classic use of this material setting.

Refraction

Refraction is the change in direction of a wave due to a change in its transmission medium. And what does that mean in 3D terms you ask. The index of refraction (IOR) controls the amount by which the material refracts transmitted light. The IOR of air, 1.0, causes no distortion of objects behind the transparent object. At 1.5 the object behind distorts greatly (like a glass marble). At an IOR slightly less than 1.0, the object reflects along its edges, like a bubble seen from under water. Default=1.5 (the IOR of typical glass). As this setting is used mainly with glass it is often a sub option to Transparency or Opacity.

3D sphere with evidence of refraction

Specular

Glossiness, also called specular, settings are similar to reflection settings in that they will reflect a certain proportion of surrounding objects but glossiness is more geared toward giving the object a shiny appearance. Ideally used when representing high gloss plastics or varnished wood or stone.

3D spheres with glossy material

Reflection

Reflection does what it says, simple as that! Ideal for representing mirrors or high shine, smooth metals like chrome.

3D sphere with reflective finish

Bump maps can be applied to 3D models to alter surface appearances thus altering light interactions with scene objects to simulate "bumpiness". Although bump maps can simulate topology such as surface bumps and ripples, they do not actually change the 3D geometry.

3D spheres with bump map applied

Textures:

A texture is a bitmap file which is applied to the 3D model through a material and wrapped around the 3D model with the help of special mapping tools. Mapping coordinates define how the texture is wrapped around the 3D model. The process of applying and modifying the mapping coordinates in 3D is a process often called UV unwrapping. 

A texture will not override the settings of a materials when added to it but rather work alongside the existing material setting to create a more realistic finish. For example an image of wood grain could be added as a texture to a material which already has a glossy effect to create a high gloss, wood finish. Another example would be of a floral image being added as a texture to a material with high transparency to create a patterned glass finish.

Selection of 3D textures

Next up in the 3D Modelling and Animation series is our 3D Animation Article.