Views and Visibility
For the MEP engineer, there may seem to be too many ways to control the visibility of elements in Autodesk® Revit®. Working in a shared MEP model with architectural and structural links, things get complex and fast. With competing needs and endless options, how can a firm settle on a shared plan for visibility control? Let’s start with a walkthrough the basics then analyze advantages and pitfalls of the various visibility controls of Revit.
At the very base level of Revit there are line weights. Best practice is, don’t change them. People have tried to match them to their AutoCAD® line weights, which seems legit, but it will cause issues when new families are created from the Autodesk template. The line weights mismatch from the families to the project template. It will hit again when linking in consultants’ drawings in two ways. Number one, when linked, the architectural backgrounds will look plain wrong. Number two, the host model will also appear wrong when linked into the architectural model. At the end of the day, just use the line weights provided out of the box and skip the hassle.
Line weights, color, and patterns are set in the Object Styles dialog for every Revit element by category, establishing the default appearance of every Revit element (Figure 1).
Once every element has a default appearance, some thought should be given to why that default appearance should be altered and how to best do it. The usual suspects for visibility control are outlined below.
The View Discipline
Controlled by Revit, setting the view discipline for a view automatically changes the appearance of elements based on how a discipline would typically use it. In the case of views set to Mechanical, Electrical, or Plumbing view discipline:
- MEP elements display according to object styles while all other elements are half-toned and can only be selected one at a time (not window selectable).
- Ceilings in plan views will not display.
- Most MEP elements are drawn on top of other elements regardless of the location of the cut plane, except for plumbing fixtures.
- Hidden lines are only shown for MEP elements if the Show Hidden Lines view property is checked.
- Callouts, elevations, and sections display only for corresponding disciplines in plan views.
View filters are accessed through the Filters tab in Visibility Graphics and apply only to the views they are applied. View filters allow the user to pick out certain elements in a category based off parameters for the category. This makes view filters a good choice for overriding subelements of Revit categories by view, by use of rules. A common use of view filters is to change the color of piping based off the piping system.
First a filter is created to isolate subelements of a Revit category or categories (Figure 2).
Then the visibility, color, pattern, and transparency of the isolated elements can be overridden and a halftone could also be applied in any view (Figure 3).
Because of this two-step process, the same filter can have different overrides applied in separate views, or may not be applied at all. Sometimes this is good and sometimes, not so good. The industry has been extremely creative in producing view filters to aid in visualization, design, and validation. View filters have been created to hide elements, to distinguish powered from unpowered equipment, and highlight underground circuits. There comes a point when there are too many view filters to choose from, and it is preferable to keep the number of available view filters to a manageable level. Be aware that multiple view filters applied to the same view can apply to a single element. The result is something that should show up as blue is turned blue, but is also turned off and not seen. The order that the view filters are applied will change the result, making it very difficult to diagnose problems.
Using worksets for visibility control may be controversial, but it is a tool in your arsenal and should be considered. It can simplify what is seen and what is not by reducing the number of clicks and places to look for visibility. Instead of turning multiple categories on and off in visibility graphics, all categories can be turned on as long as every element is placed on the correct workset and the view is set up to only show the required worksets. Figure 4 shows how a view used for power would control filter out HVAC, plumbing, and lighting elements.
This method requires strict adherence to worksets, but is also one of the simplest solutions for users to understand. A con to this method is when an element is required to be in multiple contradicting views; therefore, shared worksets would have to be created. Say an electrical panel needs to be seen in power sheets as well as lighting sheets. Electrical panels should then be placed on a shared electrical workset or a background workset to be seen on every plan.
Worksets can also be handy when hiding elements in an overall plan and only showing them on enlarged plans by creating enlarged worksets. Just like filters, there reaches a point when more is no longer better.
Revit provides the ability to create subcategories under program dictated categories. By assigning portions of family geometry to different subcategories, these portions can be displayed with different line weights, line colors, line patterns, and material assignments. Subtypes can also be created for equipment types, making subcategories an elegant answer to items that defy workset organization, such as mechanical equipment. A Pump may want to be on plumbing plans and power plans, but not HVAC plans. By creating a subcategory under mechanical equipment called “Pump,” users can now decide if pumps or any other kind of mechanical equipment is visible, by the equipment type. Watch out for poor subcategory naming. Without strict naming standards for subcategories, projects can and will include subcategories for Pump, pumps, M-pump, Pumps, and who knows what else (Figure 5).
Another drawback to subcategories is the inability to control them as linked Revit files without digging deep into the linked project. This is shown when sharing the project outside of a firm. The receiving firm will not have context to what the subcategories are and why they exist. Autodesk Seek has created a standard subcategory naming convention and so have other standards such as ANZRS. That being said, only your firm can say what works best for you and your clients.
View templates are Revit’s way of taking anything that can affect a view and packaging it to be applied or assigned to other views. It’s important to understand the options of applying a view template and assigning one. When a view template is applied to a view it is a onetime setting that will not lock in. If the template is altered, no changes will reflect in the view, nor will an applied view template stop users from making view changes after the template is applied. To apply a view template, go to the View tab of the ribbon, select the View templates drop-down, and pick “Apply Template properties to Current View” (Figure 6).
An assigned view template locks users out of making changes to the view that are dictated by the template. Instead, the user must alter the template itself. Altering the template will in turn push those changes to each view that the template is assigned to. To assign a view template, choose the template under Identity Data in the view properties (Figure 7).
So when to apply and when to assign? It might be easiest to just ask the question, “Does this template need to be associated with more than one view?” If that is the case, assigning is the way to go. By assigning the template the user can be assured that each view that calls this template will have an identical setup, and that setup can be refined over time by altering the template. For one-off situations, applying the template can quickly get the user to a great starting point, and leave the user free to tweak the visibility setting without having to navigate the template further.
Taking things a step further, it can make sense to do both. Templates can be assigned to control the linked architectural and structural files. Then a separate template can be applied to control the host file for discipline specific setups such as lighting, plumbing, and HVAC. In this way each discipline will work off an identical background, but also have the discipline-specific control of the view. In cases like this, the user may find that the applied discipline view template may need to be updated as the project progresses and reapplied. This is easily done by selecting all the appropriate views in the project browser, right clicking, and selecting “Apply Template Properties….”
Hierarchy of Visibility
There are still many more parts of Revit that effect visibility and further complicate things in a single file. Once worksharing and file linking are added to the mix, it becomes difficult to remember which rules apply and why something is being seen or not seen. Understanding the hierarchy of Revit visibility can help the user sort out what went wrong. The higher numbers in the list below trump the lower numbers.
- Project Object Styles
- VG Overrides
- Phasing Overrides
- View Filters
- Override Graphics in View by Element
- Override Graphics in View Halftone
How to best leverage these techniques to work for your firm’s processes may take a bit of trial and error. In general, Object Styles should lock in the defaults, then Worksets can be used to limit unneeded elements. View Filters are used to change the appearance of elements by system or condition. Subcategories can be used to refine the visibility of elements shared by multiple disciplines and help limit the number of view filters. Wrap it all up in applied and assigned view templates to ensure consistency and you have a functional approach that is easy for users and support.