Now that we’ve covered the basics of material definition in Part 1 (Graphic, Appearance, Appearance Assets), we can investigate the most typical Revit material problems
- Grey materials
- Duplicate Appearance Assets
- Autodesk materials.
Part 2: Common Material Problems
Hunting Down Default Grey Materials
A common problem with fast-track projects is that a design team may sometimes forget to assign appropriate materials during the modelling phase. This is especially true if the office does not have a material library standard and every material must be created on the fly. Usually the initial focus is on spatial layout rather than material creation. If no materials are specified, Revit will use “default” materials.
Default materials are grey (RGB 80 80 80) and 50% reflective (glossy). They do not look like anything that we would be familiar with in real life. A good way to hunt these materials down for replacement is to create a Material Takeoff schedule of all the elements in the model and filter by material. Here’s how to execute this process:
- Select View>Schedules>Material Takeoff
- Rename the Schedule “Default Materials”
- Add the “Family and Type” and the “Material:Name” Fields
- Add a Filter for “Material Name” equals “Default”
- Select all the resulting objects in the schedule
- Open a 3D View that includes the whole model
- Middle-mouse click into an empty area to keep the selection active
- Use the “Isolate Element” button to isolate the delinquent elements
Now that you’ve isolated the elements with default materials, change them to the appropriate materials. You can easily use this technique by copying the schedule to all your projects or by including it in your project template(s). You can use the schedule as a quality control mechanism, to keep track of any material mistakes.
By Category Materials
Another source of Generic Grey Materials are unfilled “By Category” materials. Revit System families, such as Floors, Masses, Roofs and Walls have default “By Category” materials applied to them. This is meant to help the Revit workflow, so users can start modelling elements before applying a material or apply a material across all the elements at the same time. The animation below shows how you would go about replacing these “By Category” materials.
If you forget to specify the “By Category” materials as shown above, they will show up as grey Default materials. In practice, it is usually best to assign materials to individual objects rather than changing the “By Category” material. It’s a bit more work, but it gives you full control over material assignment and eliminates any assumptions.
Secretly Default Materials
Sometimes users set a Graphic Shading color without changing the Appearances tab’s Generic Color. Everything seems fine, but the colors disappear at render time. The solution is to assign a material on the Appearance tab instead of the Graphic tab and ideally to select “Use Render Appearance” in the Graphic tab. The distinction between Graphic and Appearance of materials was covered more extensively in Part 1.
Duplicate Assets – Unwanted Material Changes
Duplicating Appearance Asset names can result in materials that seemingly change appearance on their own. This can create huge problems if you don’t know why your materials are changing on their own and need to do some last minutes renders.
There are two scenarios that lead to unwanted Appearance Assets:
- Using the “Duplicate Material Asset” button
- Creating families with Generic Material Asset names
Let’s look at the first scenario.
Duplicating Material without changing material Appearance Asset names
If you duplicate a material, but do not change the Appearance Asset name, all materials with the same Appearance Asset name will be tied together. Notice how the Appearance Asset name still says “Blue” in the duplicate material.
To complicate the matter, if you’ve duplicated materials and try to rename the material’s Appearance Asset name, it will be changed in both. It is unclear whether this is a bug or working by design. Usually changing the Appearance asset name disrupts the appearance Asset link, but not if you used the “Duplicate” material button.
The solution is to use the “New Material” button for all new materials rather the problematic “Duplicate” button. This will help prevent any unwanted links between different materials. Feel free to use the “Duplicate” button for materials that have the exact same appearances, but be aware that this can lead to problems down the line.
Loading Families with Generic Material Asset names
Creating new materials in families without changing their default Appearance Asset Names creates problems. Let’s look at an example.
A user creates a chair, table and plate with new materials. but does not change the material Appearance Asset names. Since the users did not change the asset name, each family’s material Appearance Assets remains the default: “Generic” and “Generic (1)”. There are no conflicts yet and no shared Appearance Assets since the Assets are isolated within the families.
- Material: Table Appearance Asset: Generic
- Material: Table Legs Appearance Asset: Generic(1)
- Material: Chair Appearance Asset: Generic
- Material: Chair Legs Appearance Asset: Generic(1)
- Material: Plate Appearance Asset: Generic
As soon as the families are imported into the main project, the material’s Appearance Asset’s names begin conflicting. They are all named the same, so Revit has to pick which one is right. The first definition that was imported will win and overwrite the other ones. Most Revit project templates already includes a “Default” material that uses the “Generic” Material asset definition, so this will likely be the definition that wins, resulting in a proliferation of grey materials when families are imported in the project.
This issue may not be apparent right away, but at some point Revit will start changing materials to reflect the duplicate Material Appearance Asset definition. Materials with duplicate Material Appearance Asset definitions are tied to each other’s Appearance Asset. If you change one material Appearance, it will affect all other materials sharing the same Appearance Asset. You can see these results in the animation above.
You can prevent the problem if you create unique Appearance Asset names before uploading your families to the project. An even better long term solution is to create a consistent material library standard and place it in your family template. You will then avoid problems that stem from users quickly creating materials and not specifying the Appearance Assets names.
Unfortunately, once the families have been imported, it is not possible to fix their Asset Appearance names in the individual families and re-upload them into the project unless you first delete the problematic materials in the project or rename the material in the family. This is a complicated and somewhat dangerous procedure, so we will ignore it for now. The only feasible way to fix the problem is to re-assign proper Appearance Asset names in the project’s material browser. Like most problems in Revit, it is easier to prevent the problem than to fix it. Let’s go through this method.
Troubleshooting and Fixing Materials with Duplicate Appearance Assets
Let’s examine how to fix a project with conflicting Appearance Assets names. The first thing we have to do is identify the materials that are sharing Appearance Assets. Go to the project’s Material Browser and look for materials with the Hand/Sharing icon showing any other number than zero. In our example, all materials are shared, so they will all have a number higher than zero.
If your office has created a proper material library standard, you have the option to use the “replace asset button”. We do not recommend using Autodesk’s “out of the box” material library.
We will proceed assuming that your office has not set up a material standard library. We therefore have to use the “Duplicate Asset” button and rename each asset with a unique name. To keep things simple, we will rename the Material Appearance Asset to match the material’s name.
- Material: Table Appearance Asset: Table
- Material: Table Legs Appearance Asset: Table Legs
- Material: Chair Appearance Asset: Chair
- Material: Chair Legs Appearance Asset: Chair Legs
- Material: Plate Appearance Asset: Plate
Please note: The Appearance Asset names could be more specific. Naming something “Table” is not specific enough for a large project with multiple tables and table materials, but it will be fine for the purpose of this example.
Once the Appearance Assets have been duplicated and renamed, there should be no shared Appearance Assets shared between materials. The material links are broken and we are ready to redefine the Appearance of the materials. This is a tedious process, you will need to redo all the initial work defining the material’s Appearance properties manually.
Hopefully revealing the difficulty of fixing this issue will encourage offices to create a material standard library and inspire users to define the material Appearance Asset name from the get-go. Since the problem applies to any imported family, we also suggest that you check families downloaded from the internet for any problematic Material Asset names. Always rename material Appearance Assets that are named “Generic”.
To automate the material standard checking process, you can investigate free tools such as Revit’s Model Review to hunt down any Appearance Asset with the name “Generic”.
Please note: In the previous article, we were discussing “Material Appearance Assets” with the name “Generic“. This is different than our new topic with a different use of the word generic: Creating “Generic Materials” instead of “Autodesk Materials”.
Autodesk Materials are packaged materials meant to simplify the act of creating typical materials. Unfortunately, they are not well implemented and tend to create more problems than solutions.
The alternative to an Autodesk Material is a Generic Material. Generic materials are better than Autodesk materials because they allow you to use the full gamut of material properties that are required. Many of the material properties don’t need to be used, but at least they are available to you, should you ever need them. Understandably, this long list of options can be daunting for beginners.
On the other hand, Autodesk materials hide many of these properties in an attempt to simplify the creation of common materials. The unfortunate result is that these materials restrict flexibility and confuses designers who do not know how to access more material properties. Oftentimes, designer are unaware that they can create Generic Materials because they have been using the “Duplicate Material” button and have not yet discovered the “Create New Material” button.
The following chart exposes the properties of each materials. You will notice that the extensive list of Generic Material parameters are not present in the Autodesk Material, instead they are replaced with a minimal custom interface.
Here is a comparison of a glass material that uses a Generic material and an Autodesk material with a small set of custom Autodesk parameters for glazing.
Let’s analyze the Autodesk Glazing Material, it is a great example of the issues associated with Autodesk Materials. It offers the following options:
- Blue Green
- Custom color
- Reflectance: 0-100
- Sheets of Glass: 1-6
- Tint color
Right away, red flags pop up: How does the color of the glass differ from the tint? What percentage of the tint is applied onto the color and how much does it affect it? Why would anything need a tint, can we not just have an accurate color or texture in the first place?
There is another bigger problem with the glass material: It is impossible to know or control the transparency! Perhaps the color affects the transparency? If our glass specification says that the glass is 97% transparent, we cannot be sure that we are showing this in our BIM model. Maybe our model is accurate, maybe it isn’t. BIM models should be as accurate as possible and avoid arbitrary values.
The number of glass sheets is also confusing. Is this meant for six sheets of glass that was modeled as a monolithic sheet of glass? How exactly does this modify our material? The logic behind this parameter is obtuse.
What about frosted glass? Is it simply impossible to achieve with the glass material since the required parameters, glossiness and translucency, are not present.
We can look at other problems that this chart exposes. For example, it is impossible to apply a bump map to an Autodesk Metal or Wall Paint material.
Another problem with Autodesk materials is that they do not convert well to other render engines. So if you are planning on using Octane, Corona or Iray+, you have an extra reason to avoid Autodesk materials.
When confronted with a problematic Autodesk Material, the best thing to do is to delete it and to start the material from scratch so that you have access to all the material options. Unfortunately, Autodesk Materials will cause more issues than they’re worth and it best to avoid them from the start.
Thankfully Revit does not allow you to create an Autodesk Material, only to use existing ones. I suggest removing these materials from your office material template and from your active projects if they are giving you any problems or confusing designers.
This concludes our foray in the world of Revit material problems. Our next excursion will delve in the world of material realism.
If anything confuses you or requires further explanation, please let us know in the comments.