OpenPBR strengthens interoperability, enabling enhanced creativity

Our ways of working are constantly evolving towards greater collaboration, necessitating improved interoperability between various tools and companies. One of the areas that this impacts is 3D creation, an area in which we have been working to provide new solutions for authoring and sharing digital assets such as materials.

This is why we are delighted to announce the launch of OpenPBR, a new digital material model designed in collaboration with Autodesk under the guidance of the MaterialX Technical Steering Committee. It is a new step towards more convergence in the industry and more efficient workflows for 3D content creators.

Digital materials are a description of a surface’s look: varnished cherry wood, shiny blue plastic, frosted glass, or polished green metallic car paint. How to express materials is the role of the material model: a well-defined list of properties, with clear meanings and possible values, exposed to an artist through the UI of their editor.

Determining a convenient, simple, yet expressive set of properties is the tricky part. Over the years, consensus has emerged over what some of those properties should be and how they should behave, for example most models provide control over the roughness of the material and how metallic it is. But as 3D technology has become more sophisticated and we’ve gained the ability to simulate more complex effects and materials, such as translucent iridescent pearl or dusty brushed metal, different companies have tested slightly different decisions and their material models have yet to converge. Because artists use a variety of tools in their workflows, these small misalignments can amount to hours of additional work ironing out look differences.

Alongside Autodesk, we agreed on the need to join forces and propose a solution. We’ve combined our existing material models Adobe Standard Material and Autodesk Standard Surface into one that we call OpenPBR, in which “Open” refers to the governance and “PBR” stands for “Physically Based Rendering”.

OpenPBR is a highly art-directable material model: an expressive yet intuitive set of parameters, neatly grouped, with direct control over the perceived colors, detailed enough to represent most real-world materials. It is physically based, meaning that materials look realistic by default, while still giving artists the freedom to represent imaginary ones. OpenPBR aims to strike a balance between simplicity of use and expressivity.

We want artists’ materials to operate in as many production pipelines as possible, regardless of the industry they work in. In order to enable more actors to contribute, and so that anyone can implement it into their own software, we’re making the standard open. This is why OpenPBR is under the governance of the Academy Software Foundation (ASWF), the same group that hosts great projects like OpenColorIO. More specifically, OpenPBR is a subproject of MaterialX. We would like to express our sincere thanks to the Academy Software Foundation for its support and advice.

OpenPBR is still in a draft state and, with the contribution of other companies, we expect to publish the specification in the coming months. It will then gradually be implemented into our Substance ecosystem. There’s still a lot of work ahead, but we are already very happy with the results, and we hope other industry actors will join this initiative and add support for OpenPBR to their own tools

We would like to thank Julien Guertault, Peter Kutz, Andrea Machizaud, Nikie Monteleone, and Anthony Salvi for their contributions to this article:

"Our goals were all aligned from the start. "Lets help artists by creating a stronger, more artist friendly bridge between software applications." I can't count the amount of times I've gone back and forth from one software package to another with completely unexpected results. OpenPBR will eliminate the technical worry of "how will I achieve what I did here... over there?" Artists will have more time to create with less worry of how they will make it work later knowing that it just will. As a 3D Artist with most of my experience in Look Development, I couldn't be happier for the possibilities of OpenPBR's future."

- Nikie Monteleone, 3D art director and senior artist, 3D&I, Adobe

"One of the coolest things about OpenPBR is the way it’s specified as a description of the physical structure of the material as opposed to a specific set of formulas. This allows each renderer to implement the model in the most physically correct way that is practical in that context. Defining the model in this way lets us achieve interoperability and user-friendliness without sacrificing the sophisticated appearance that results from physical correctness. For example, our implementation at Adobe aims to be fully energy-conserving and compatible with different path-tracing algorithms, which gives it a really nice look right out of the box."

- Peter Kutz, senior rendering software engineer, 3D&I, Adobe

"What struck me the most about this initiative, is that even though we were two groups from two different large companies, we worked as one team on a common goal. When there was a choice to make, no one stayed entrenched in their position, but instead, the interest of the artist was put front and center every single time. To be fair, rendering engineers tend to be passionate, so right from the start the barriers disappeared very quickly, as the technical discussion took over."

- Julien Guertault, senior software engineer, 3D&I, Adobe

"I have always been passionate about material appearances, and I am really grateful for the opportunity to work on such a project. I do believe OpenPBR will be a great addition and improvement in material workflow in any 3D tool. It felt great to have several companies joining efforts on trying to improve the material workflow for artists by using a common approach rather than focusing on different material models which is always a pain point to deal with when switching tools. I can’t wait to see more people taking interest and joining the OpenPBR project."

- Andrea Machizaud, senior software engineer, 3D&I, Adobe

"As an artist, defining the appearance of your 3D object is a very important step. And all this has to work within a set of tools that can evolve. That's why the creation of digital materials is crucial. We believe that digital material authoring should be accessible, creative, accurate to reality and, above all, future-proof. That's why working together and sharing our expertise and experience of digital materials with other 3D players was an essential component here. We strongly believe that this new digital material model will provide artists with the creativity and flexibility they need in their work today and in the future."

- Anthoni Salvi, director of product management, 3D&I, Adobe