Mar. 14, 2019
Autodesk Revit: PBR material workflow for architecture
“Substance was mostly used within the M&E space, but in recent years it has also become the leading material ecosystem for industrial design and AEC.”
Hi guys, thanks for taking the time for this interview!
Could you please present yourselves to the community?
I’ve been a rendering architect and developer working on 3D graphics technology for the last 20 years. I’ve been with Autodesk for about 12 years now, working on real-time rendering, ray tracing, shaders, materials, and so on.
I’ve been with Autodesk for more than 20 years in various roles in the Media & Entertainment group, and the cloud rendering service. I did illustrations, sample files, animations, documentation, and support material. I have extensive knowledge of rendering and digital content creation tools, not just of those by Autodesk.Henrik Edstrom & Roberto Ziche.
A composite of 13 floor materials generated from a single Substance file
What are your respective roles at Autodesk?
Henrik: I’m the lead software architect for our graphics platform group, where we develop shared graphics technology for most of our bigger products, including 3ds Max, Maya, Revit, Fusion 360, Inventor, InfraWorks, and AutoCAD. Our responsibilities include both the graphics engines (viewport, offline, web, cloud) and content libraries for materials and other assets.
Roberto: I’m covering a few roles supporting the Cloud Rendering team. One of them is the creation of the new library of materials for Fusion 360 and Revit.
How are architects and ArchViz currently interacting with virtual materials?
Roberto: Each user has a different workflow, but there are definitely two major categories. One is the need for generic materials that are used just to make a space look realistic. In Revit, most of the time is spent on designing building spaces, but the final interior design is not yet a concern. All you need is a variety of photoreal materials that cover a range of options. Substance procedural textures are excellent for those material types.
The second category is when specific manufactured materials are needed. Things are trickier here, where materials need to look exactly like the real ones, and there is so much variety that a pure procedural workflow might not be possible. But Substance can procedurally process photos, adding a hybrid way to create new textures and variations while still using photo references as source material.
When and how did you discover Substance?
Henrik: We looked at Substance many years ago as a potential companion technology to our existing material offerings. At that time, Substance was mostly used within the M&E space, but in recent years it has also become the leading material ecosystem for industrial design and AEC.
Roberto: I’ve been following Substance for a long time. I remember playing with Substance files when they started being supported in 3ds Max. I followed the evolution of Substance and worked on it a couple of more times when we did test integrations for our cloud rendering engine. But I only recently picked it up and started authoring some materials. The main reason was that the photographic-based workflow I was using for Autodesk Fusion 360 materials wasn’t working well for the architectural materials required in Revit. Large patches, tiling, and variety were much easier to create in a fully procedural way.
How can Substance materials and PBR be useful in a Revit-based workflow?
Henrik: It gives our users access to a much wider range of materials than Autodesk can provide. The ability to customize a Substance material through intuitive parameters also makes it much easier to create variations compared to the current system we have in Revit based on static bitmaps.
Roberto: While Revit does not currently have native support for Substance files, the textures created in Substance can be used by Revit materials. As I mentioned above, architectural materials must be high quality, with good tiling, and often many varieties of base materials are required. Finding (or capturing) pictures is extremely difficult and the work to clean them and make them seamless is time-consuming. Often results are inconsistent and even, in some cases, just don’t come out right. Substance requires some effort for the original authoring of new materials, but variations are often simple and can be created in high numbers.
Could you tell us more about the demo video you made for Autodesk University 2018?
Henrik: The video basically shows how you can use Substance already today without any native support in Revit. It’s quite manual and inflexible, which is why we’re so excited about the collaboration with Allegorithmic to enhance this workflow.
Roberto: The video shows a typical workflow where Substance is used to create textures for a Revit material. Revit 2019 introduced new physically accurate materials, and the characteristics of a standard PBR material such as diffuse, roughness, bump, can be used directly with no modifications. The drawback of this method is that textures are static, representing whatever settings were used when they were created. If you want a parameter to change – to reflect, for example, the amount of dirt on a brick wall – all the textures would need to be re-generated.
Do you have a few suggested steps that would guide Revit users through the whole PBR material creation process within Revit?
Roberto: We suggest using the new physically accurate materials introduced with Revit 2019 (Found in the Appearance Library under Miscellaneous->Base Materials, as shown in the picture below), where you can easily plug in the textures created by a PBR Substance workflow. Pay attention to color saturation and levels. For photorealistic results, you don’t want pure colors, perfect blacks, or too much saturation. Use sRGB color-managed textures, and make sure bump and normal texture RGB levels are linear. And while color, roughness, and bump textures are well known, I also use the Advanced Highlight Controls Color to simulate occlusion in small cracks or dents of surfaces.
We’re very happy to start working more in-depth with the Revit team. Could you tell us more about what this collaboration encompasses?
Henrik: We’ll work together to make sure the Substance workflow fits in well with how Revit users expect to work with materials. We’ll also collaborate on APIs and data models to make sure we can deliver a very integrated user experience.
How do you see the workflow of Revit users evolving in the future?
Roberto: The ideal workflow would bring Substance right into Revit so that saving textures and creating materials pointing to them can be avoided. Instead, a user would have access to the actual Substance files with all their parameters, preview the result, and textures would be generated at viewport and render quality as needed.
Henrik: Having direct access to Substance Source inside of Revit would be a great addition.
What software is currently used in combination with Revit?
Henrik: Enscape is very popular as a companion product to Revit, but Lumion and Fuzor are used as well. For more advanced presentations, the model is typically exported to 3ds Max, and then either Unity or Unreal is used for real-time presentations and V-Ray for offline rendering and animations.
Roberto: Clever and Twinmotion are others that are also used with Revit for final presentations.
Examples of scenes rendered combining Substance materials and rendered in Enscape, by Hans-sen Hoefer: