Using Micro Roughness with Metals

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Using Micro Roughness with Metals

What is Micro Roughness?
How exactly will it help me to create better metallic shaders?

These are some of the questions that will be answered in this article.

What is Micro Roughness?

Micro Roughness simulates the natural phenomenon where smooth objects appear to have reflections with a variation in the amount of roughness, as the viewing angle changes from normal to shallow. This practically means that while taking a close-up look at a metallic sphere with a rough surface, you will notice that roughness decreases when the eye goes to grazing angles.

There is an excellent tutorial created by Patrick Nieborg that describes in detail the way Micro Roughness works and you should definitely watch it!

How exactly will it help me in creating better metallic shaders?

Micro Roughness was designed as a property of the surface, taking the already physically-based material editor, one step forward. By default, rough materials in Thea have a uniform value of roughness, no matter how you look at them. We created the following images of a metal shader having a roughness value of 30%. The only difference between them is Micro Roughness.

Difference between the two renderings.

By looking at the Diff image we can see where Micro Rougness has been applied, making the reflections more evident and the object shinier.

Here are the two images in higher resolution. Micro Roughness On  |  Micro Roughness Off

Thank you for reading through this article and feel free to post your renderings in the comments below!

Note: Micro Roughness is available for Basic and Coating layers but can also be used with Glossy and SSS layers starting from version 1.5.08 onward.

With deep knowledge of nearly every 3D platform out there and a passion for rendering, George works restlessly in providing exceptional content, tutorials and training.
  • Rombout

    The video isn’t not really about metals…

    • George Gliatis

      Hi Rombout! The video describes the logic behind Micro Roughness and users need to watch it in order to get a better idea of what Micro Roughness is. This article was written to point out the benefits of using Micro Roughness with Metals.

      • Rombout

        okay, with the title i thought the article would describe more info about using it with metals

        • George Gliatis

          Not sure what you expected to be honest. It does explain the reason of using it with metals and I believe that it is important for users to create metals in this way too.

          • Rombout

            Well seeing the example here, i thought it would be explained better how to use them with metals. I find the info about the width for micro roughness a bit vague…

  • Ioannis Pantazopoulos

    Micro roughness in Thea basically implements a physically-based approach on how roughness changes with the viewing angle. In many cases, this effect can be seen on metals (that we have chosen for the article here) but also on other materials (for example plastics).