How do I know my materials will look right in the final render?
Rob replies This is a very good question and the answer deals with a few aspects of material creation that are really important to producing believable renders. The overall answer is a combination of things, but the main part would be to have a standardised method for creation that you stick to, allowing you to always work in a predictable situation. This will support your ability to recognise faults that lie elsewhere in your scene, such as lighting or render settings.
The trick here is to set up an object that can cater to different types of material, from solid surfaces to transparent or translucent ones. Usually a sphere with some detail works well and, in this example, I have a ring beneath the surface to help when working with SSS.
Other elements you will need to make this scene work are an environment, which should have something that can show in reflective materials. I actually use a combination HDRI on a sky dome as well as an image-based spot light. This means I can turn light sources on and off, which is great for when you’re working with light-emitting materials.
When it comes to the lighting on the scene it is more important to get simple but variable options so you can easily deal with different render requirements. For example, if you find yourself working on a project that doesn’t have a GI solution, you will want to switch to a procedural lighting setup, using your host software’s procedural lights, which may or may not include falloff.
These days it’s more common than not that you will be using a linear workflow, but keep in mind that you may not. It’s worth having a duplicate of the material setup scene for this, as turning it off will have quite a few knock-on effects for your materials.
Next, and in some ways most importantly, there is the element of scale. I talk about this a lot in my classes and training articles and it is becoming more and more important as we move to ever more physically accurate render solutions. Set up your scene using a known scale and create your materials based on this scale. A metre is a good middle ground and caters well for everything from product design to architectural visualisation. Having a grid in your studio is a good way to help reinforce this, but keep it mid-grey to avoid it skewing your material work.
Finally there are the physical attributes. Most apps let you specify things like refractive index and Fresnel settings, and even IES profiles; so a quick search can help bring the most realism to your work.
Set up your scene using a known scale and create your materials based on this scale