Establishing Origins - Part 1 (Revit users)
How to get everyone aligned quickly and easily? …at least 90% of the time.
We have all been there, it is the first coordination meeting and everyone’s model seems to come into Navisworks everywhere but the right spot. Most of us in the 3D coordination field are self-taught. We may have learned the software at college or a trade school, or if you’re like me you learned from my two favorite teachers trial and error. We may have learned our particular trade through apprenticeship and field work or we are learning the trade through guidance from our peers at the company we work for. However you came about your training one thing is likely certain, it was not standardized in any way. To a large degree the BIM/VDC 3D coordination process is still relatively new and there are no set industry wide workflows. To be frank a lot of us just wing it.
This simple fact can be a double edged sword. On one hand figuring things out for ourselves has allowed us to figure out the best method that works for each of us individually. The down side to that is that this approach has steered the overall 3D coordination process into the wild west. We all have our own unique workflows and processes and they don’t always mesh well with others. This point is illustrated every time we join our first coordination meeting with a new team. On virtually every project we have done it is fairly typical for the first one or two meetings to be spent reviewing the project BIM guidelines, schedules and trying to get everyone’s models aligned. As a result, these are not very productive meetings, and the project schedule just keeps moving along.
One thing we can do to help tighten up this phase of coordination and expedite the process is to try to standardize the process of alignment. Our group would like to spread the word on a simple and effective way to get everyone aligned right from the start. As the subtitle to this blog mentions this process will align everyone right from the start at least 90% of the time. However, you will find that every now and then for some reason a design professional has gone rogue and used some mystery alignment method that does not automatically line up their design model to the rest of the design team models. We will cover that in a later blog.
How do we get set up? Well the answer is surprisingly simple. For some of us this will be old hat, but for others it will be welcomed news. Let’s walk through a common project set up in Revit. We will help the CAD folks as well in a later post.
First save all the background models to their own folder. I prefer to keep my backgrounds in a specific folder labeled “Design File References” mainly to help me from accidentally messing with them during coordination (see Figure 1). Once all the necessary backgrounds are gathered update them to whatever version of Revit you will be using. If you get a message from Revit that reads “This model has been transmitted from some other location. What do you want to do?” I always opt to “Save this model as a central in its current location” (see Figure 2). I prefer to keep the original backgrounds as untouched as possible. This includes keeping any worksets the designers have established; you never know when they will come in handy.
Note: some projects are aligned by the Survey Point. This blog will focus on Project Base Point as most of the projects I have come across use that as the shared origins. This process works either way.
Start by creating a new project using whatever template you normally use. Name it and save it in the way you always do. After doing that the first background you will want to open will be the Architectural model. This model will be used to establish the Project Base Point. Once you have the Arch model updated, saved as a central and ready to go, open a 3D view with no view template. You want a raw view of everything. Now you can find the Project Base Point one of two ways. You can just Reveal Hidden Elements. Sometimes though the model has a very large number of elements, or the origins are very far away from the building, this can cause a ton of lag when trying to move the model around or zoom in and out of a certain area. Lag is bad. If that happens the other way of revealing the Project Base Point might be desirable. For that open the Visibility/Graphics Overrides window. With that open turn off all Annotation Categories, Analytical Model Categories and Imported Categories. Then go to the Model Categories and turn off everything except Site. Expand the Site category and hide everything except the Project Base Point and Survey Point. With just those two items shown you can move around the model lag free (see Figure 3).
Now you can click on the Project Base Point icon and reveal the model origins (see Figure 4). At this point I like to create a simple .txt document with Notepad and copy all the project transforms and save them (see Figure 5). This can be shared with other team members if needed and it will come in handy when creating a .DWG origins file for those using CAD software to model their systems.
Once you have the Architectural origins copied and saved it’s time to transfer them to your working model. Open a 3D view and Reveal Hidden Elements. Then click your Project Base point and copy the transforms into the corresponding axes (see figure 6). Sometimes the project origins are way off from the project base point. Revit has a 20-mile model geometry limit so if one of the X or Y coordinates is more than 10 miles from the center you will get a message that reads “The Project Base Point cannot be placed more than 10 miles/16 kilometers from its startup location. What would you like to do?” (see Figure 7). If this happens choose to “Move the Project Base Point to its start up location”. Depending on which version of Revit you are using this is done in one of two ways. In 2020.2.1 and earlier: Un-clip base point and use Relocate Project to move project base point (see Figure 8). In 2020.2.2 and later: Go to Manage > Coordinates > Specify Coordinates at Point (see Figure 9). Then continue to copy and paste the transforms as you normally would. Note that moving the Project Base Point to the new startup location will also move the Survey Point. I like to set those transforms to match the Architectural Background as well.
Note: If you have to move the start up location you will notice that the Specify Shared Coordinates window displays the Angle from Project North to True North in minutes, degrees and seconds rather than an angular degree. DO NOT COPY THE ANGLE IN THIS SPOT. Just move the X, Y and Z, then go to your Architectural background 3D view and open the Specify Coordinates at Point menu and copy and paste the correct Minutes, Degrees and Seconds. Otherwise your angle will end up slightly off.
Now that our shared Project Base Point has been established it’s time to link our backgrounds. But first sync and save. It should not need repeating, but I will anyway, sync and save often. There is no such thing and syncing and saving too much. After that is done go to Insert > Link Revit or Manage > Manage Link and insert all your backgrounds by Auto – Project Base Point to Project Base Point and everything will come in perfectly aligned, 90% of the time anyway (see Figure 10). Now export all of your backgrounds with the Shared Coordinates option in the Revit Navisworks exporter tool (see Figure 11). And we’re ready to append our backgrounds to our coordination .NWF. Open your .NWF and append away. All of your exported .NWC’s will come into Navisworks with the Units and Transforms already set (see Figure 12).
So if you didn’t before, now you know.
And as G.I. Joe always said…”Knowing Is Half The Battle.”
