basics: diffuse

In our first 3D Essentials exploring materials, let’s look at Diffuse properties

Mike Griggs explores the Diffuse properties of materials with this essential guide

I f you’re new to CGI, you may feel that there are far too many tools to choose from in a dizzying array of software. This series aims to break everything in CGI down to the very basics, so that every artist can be armed with the knowledge of which tool is best. This issue we start exploring different types of materials and shaders by focusing on Diffuse properties.

One of the simplest ways to bring some extra life to any 3D object is to add colour and texture to it. There are a variety of names given to this process, adding shaders or materials or even textures. A rule of thumb is that a ‘texture’ is an image that is used to drive a property of a ‘material’, which defines the basic properties of the surface of the object. This itself is the child of a ‘shader’, which is effectively a holding group for all the various elements – some software can blend materials together to give the appearance of rusting metal, for example.

A material is defined by a range of different parameters and again this is software dependant. While ‘physically based rendering’ or PBR is becoming a standard for contemporary material systems, it is not consistently applied across all software, so therefore we will try and take a look at ‘legacy’ uses as well.

The first material property that is consistent across nearly all material types is its Diffuse properties. Diffuse or ‘Albedo’ properties control the underlying colour of a material on an object. The Diffuse properties are usually divided into two distinct elements, one is the Diffuse colour and the other is the Diffuse weight or value, which effectively determines the brightness of the colour underneath.

Both of these properties can, if the artist chooses, be driven by textures, with Diffuse weight being driven by a black and white patterned image.

Using the Diffuse as a base for any new material/shader system is a good way to learn the basics of creating successful and convincing materials. Even though Diffuse properties may not be used very much in metallic materials, knowing why is one of the keys to making any application’s shader system work for you.