As you’ve progressed through your Autodesk® Revit® implementation into your office workflow, just how far have you utilized Revit within your daily design and document process? Typically, the first step is to match the graphic standards of the documents you had previously created using some other CAD platform such as AutoCAD®. Further steps might include such things as integrating trade coordination, quantity takeoffs, and analysis. Many companies only make it to the first step without realizing the true benefits of Revit and BIM. One great way to learn how to leverage the underlying data in Revit is to utilize graphic filters. This little known and easy-to-use feature will help expose some of the many paybacks of investing in a BIM workflow. It can also serve as a tool for quality control and project management that provides graphical and intuitive feedback.
What are Filters and Why Do We Need Them?
As mentioned previously, graphics are typically the first hurdle in a Revit implementation and are very important to initial success. There are a number of ways to adjust the appearance of objects in Revit; Object Styles, Visibility Graphics, Phasing, View Depth, Worksets, Linked Files, View Templates, Linework, and so on. Revit objects belong to Categories instead of Layers, and Categories have appearance settings that are applied to all objects in a category. Category appearance settings control object characteristics of line color, line weight, and line pattern and can apply to an entire project or to individual views. At a global project level these are controlled by Object Styles. At a view level, they are controlled by Visibility Graphic Overrides.
For structural engineers, the graphics tend to be relatively simple for such things as floor plans, elevations, and details with the majority of these being fully controlled by Object Styles and Visibility Graphics Overrides. But there are some instances where that’s not enough. For example, there is no sub-category of walls for bearing versus non-bearing walls, or concrete columns versus steel columns. So how do we control the graphic representation of an object by its parameters instead of just its category? This is where filters come in. Filters allow us to quickly and effectively select and modify the appearance of objects from within the same category.
Figure 1: Filter of concrete and steel columns
While filters have not been widely used in the Structural Engineering field, they are quite common for MEP Engineers. That’s because filters are an absolute necessity in order to graphically differentiate systems, such as Supply and Return, in order to coordinate them.
The Anatomy of a Filter
Filters can be found on the View tab or by going into the Visibility Graphics of most views. The filter dialog is made up of three main sections: Filters, Categories, and Filter Rules.
Figure 2: Visibility Graphics overrides
Filters – refers to each of the named filters within the project. This is similar to other dialogs where these named rule sets can be created, duplicated, renamed, and removed. A standard naming convention should be used that is descriptive, yet brief, to help the user easily identify the rules applied to the filter.
Categories – refers to the available Revit categories of which to apply the named filter. Like schedules, this will dictate the parameters you will have available to apply rules.
Filter Rules – defines the logical statement that will determine to which objects the filter will apply. Each set of rules consist of three elements: a parameter to filter by, an operator (equals, less than, does not contain, etc.), and the value to look for in the specified parameter. Up to three logical statements can be used per filter using the “And” statement.
Figure 3: Concrete column filter
Applying a Filter
Once you have the filter defined, you may apply it to a view. To do this, go into the Visibility Graphics and select the Filters tab. You will then select the “Add” button and continue to select the named filters that you would like to add to your view. Once they are added to the view you will continue to define the overrides you would like to apply to the filter. Graphics that can be controlled are Visibility, Projection/Cut Lines and Patterns, and Transparency. Ultimately, this allows you to control your graphics by categorical parameters instead of just object categories.
Now that you’ve learned how to create a filter and apply it to a view, get imaginative and start applying them in ways that enhance your design workflow. The opportunities are limitless. Following are some ideas of ways that filters can assist.
Filters for Documentation
There are always cases where you need to highlight specific kinds of elements, or conversely, greytone them or even hide them. Revit Categories don’t provide great flexibility, and overriding individual elements can be time consuming and cause problems down the road. Use Filters to dig into the Revit parameters of the categories and override the graphics of the targeted elements.
- Bearing wall and shear wall pattern overrides
- Visibility of steel versus concrete columns
- Category (bracing & trusses)
- Material surface shading
- Existing grids & levels
- View tags (section/elevation/callout) visibility
- Linetypes by object parameter
- Phasing or sequencing by custom parameter
- Concrete pour sequence
- Transparent floor by parameter
- Owner furnished, contractor installed
- Owner finished, owner installed
Figure 4: Bearing wall and shear wall filter
Filters for Management, Review, and Coordination
Have you ever wondered if there was another way to quality control your design and documents without using paper and a highlighter? Now there is. Set up a new Revit view of your floor plan or 3D view. Then create a filter to test your design and use graphics to highlight the correct, or offending, items. For instance, highlight moment frames in green in a 3D view so that you may graphically check that you have applied end connections correctly (see Figure 4). Or add a custom parameter to structural elements showing whether design calculations have been checked for individual elements or sections. Then set up a QC view that shows checked items in green and unchecked items in red. This can be a great way to show the project reviewer or project manager which items have been reviewed.
- Moment frames/braced frames
- Trade coordination
- Engineering review check
- Design review dates
- Fire ratings (color by rating)
- Color by associated level (3D)
- Color structural embeds by location
- Beam sizes by color
- Foundation sizes by color
- Host references
- “Appears in Schedule” custom parameter
Figure 5: Moment frame filter
Filters for Analysis
Have you ever tried transferring your Revit Structure project to structural analysis tools and received several errors or warnings regarding the connectivity of nodes? Now you can graphically check the connections of nodes in your model before exporting. Revit 2014 comes preloaded with a couple new filters in its structural template for node connectivity. Also utilize these filtered views to check your structural loading and look for things such as high moment or shear values that might require some extra attention in design.
- Analytical adjustments
- Special design calcs or considerations
- Connected analytical nodes
Figure 6: Analytical node filter
Utilize view templates to apply these filters to many other views and standardize in your company template. Since filters cannot be copied and pasted, this is the surest way to easily apply graphics settings to multiple views. View templates and filters can also be transferred between projects by using the Transfer Project Standards command.
Get Your Priorities Straight
There are times when a particular object might be selected by multiple filters at once. Fortunately, Revit has a system in place to manage this. The filters have priorities so that the filter listed as the highest priority will control its visibility. If each filter is controlling different graphic settings, then both filters may be applied with the higher ranking filter taking priority. The one exception to filter priority is the “Visibility” setting. If any of the filters has this setting unchecked, then the object will not be visible, regardless of priority.
Also look out for other conflicts with graphic overrides. Filters rank high on the list, as shown in Figure 6, but overrides that rank higher are individual element overrides and the Linework tool. You should use this list as a guide for the best ways to approach your graphics changes. Start at the bottom and work your way to the top with the Linework tool being your absolute last resort.
Many of us in this industry are graphical people who can understand illustrations better than numbers. Using graphic filters allows us to test our design and present it in a way that is easily understandable and can provide us with visual clues to designs that can be difficult to interpret on paper or by numbers. Try digging into the filters tool to see what kind of creative uses you can find. I would be interested to hear some of them.
Figure 7: Visibility overrides priorities