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The Importance of Lessons Learned and Mastering Shared Coordinates in Revit

Digital By Oct 03, 2024 No Comments

We’ve all heard the term “lessons learned,” but what does it really mean in our day-to-day work? Recently, someone told me their team doesn’t do lessons learned because it focuses on failures. That kind of mindset completely misses the point. Lessons learned are about growth and improvement, not just pointing out mistakes.

Let’s talk about a real-world example of lessons learned – dealing with shared coordinates in Revit. The process of using shared coordinates is fundamental to successful collaboration across different disciplines in construction projects. Establishing a consistent coordinate system the right way can avoid costly misalignments that arise from working in separate models.


Understanding Shared Coordinates

One recurring issue I’ve noticed across teams is the handling of shared coordinates in Revit. The example in this post is based on a lessons learned session I led on the topic.

For those unaware, in Revit, shared coordinates provide the essential framework for aligning models from different disciplines. They ensure that every model—whether architectural, structural, or civil—sits in the correct location and orientation relative to both real-world site coordinates and other models. The main elements involved are:

  • Project Base Point (PBP): The starting point for measurements in your project.
  • Survey Point (SP): Connects your model to real-world coordinates.
  • Internal Origin: An invisible anchor point used for calculations.

These elements help different teams work on their parts of a project while keeping everything aligned.

Common Issues with Shared Coordinates

We’ve seen several recurring problems:

  • Misalignment between models from different teams.
  • Confusion from using outdated coordinate systems.
  • Errors when transferring coordinates between software platforms.

In Australia, the tectonic shift of the continent has caused significant changes in the geodetic coordinate system, prompting a transition from MGA94 to MGA2020. This change reflects how Australia’s landmass has drifted about 7 cm per year, resulting in a total shift of up to 1.8 meters over the past two decades.

We’ve all seen that meme image of the bridge that doesn’t meet in the middle. Imagine if a linear infrastructure project was being designed by separate teams along it’s length. Now imagine that one team is using MGA94 and the other MGA2020. Both teams positioning are technically correct, but in fact they’re out of sync. Failing to account for this update in coordinate systems can lead to serious misalignments in construction and infrastructure projects.

The Revit Rotation to True North

In most projects, Project North is set to align with the building’s primary orientation to simplify modeling tasks. However, True North represents the actual geographical direction.

Revit allows users to rotate a model to True North independently from Project North, enabling more accurate geographic alignment without disrupting day-to-day modeling. The process involves adjusting the Project Base Point and Survey Point to align with the site’s geographic conditions, either manually or by acquiring the coordinates from linked files like site plans or survey data.

A real-world example of why it’s essential to correctly understand the relationship between True North and Project North involves a situation where a BIM Manager was reviewing and rejecting models because the rotation to True North was not 0 degrees.

The issue arose from a misunderstanding of Revit coordinates and Project North. while True North must align with the real-world geographic north, rotating Project North does not impact the shared coordinate system of the model. Project North is simply an alignment used for easier documentation and modeling, especially when the main geometry of the building is at an angle to True North

In this case, the reviewer was linking my model into other project models and claimed that the coordinates were incorrect due to the angle of True North. However, linking models based on shared coordinates verifies that the coordinate system remains accurate, regardless of the Project North rotation. The shared coordinate system governs how models align in relation to each other, not the Project North setting

An example of rotated project coordinates (left) versus rotated project north (right)

To ensure the project is documented clearly, rotating Project North allows the design to be oriented correctly on drawing sheets. This rotation is essential when the building doesn’t naturally align with True North but still needs to be represented cleanly for documentation purposes.

Aligning Drawing Sheets with Scope Boxes

The alternative to rotating Project North is to use Scope Boxes to control the orientation of views on sheets. Scope Boxes can be rotated independently of the model’s true geographic orientation, ensuring that views appear properly aligned on sheets without affecting the actual project or site coordinates. This method offers more flexibility when presenting different portions of a project that might require unique orientations across drawing sets.

Scope Boxes allow for:

  • Rotation of views without impacting the model’s coordinate system.
  • An easy way to manage view rotation where multiple rotations are required to correctly orient the drawings
  • Multiple views can reference the same Scope Box to maintain uniformity across the project’s drawings.

Using Scope Boxes can simplify drawing management and coordination without compromising the project deliverables, and eliminates the issues associated with confusion between how Project North and True North function.

Best Practices for Managing Shared Coordinates

Based experience, here are some practical steps:

Set Up Shared Coordinates Early.

Establish the shared coordinate system at the beginning of the project to ensure that all models align properly. Make sure that both Project North and True North are understood and set correctly for the entire team from the start. This will help avoid significant rework later in the project.

Model Validation.

Regularly check the integrity of the shared coordinates as the project evolves. This includes verifying that linked models align correctly, particularly if design updates or model changes are introduced

Clear Communication.

Ensure all teams are informed of any updates or changes to the coordinate system. Miscommunication about coordinate changes can lead to significant misalignments. Use a ‘master control’ or ‘datum’ model that is derived from the survey file (usually a DWG) and contains the shared coordinates.

Documentation.

Maintain detailed information related to shared coordinates in your BIM Execution Plan. Documentation ensures that everyone involved in the project—both current team members and new stakeholders—has a reference for how coordinates are being handled.

Project North and Scope Boxes.

When aligning views for documentation, use Project North to simplify the orientation on drawings without affecting the shared coordinate system. This prevents unnecessary rotation of the coordinate system itself, which can lead to misalignment issues. Additionally, if further flexibility is needed, consider using Scope Boxes to rotate views on sheets while maintaining the correct geographic positioning.


    Why Lessons Learned Matter

    So, why bring this up? Documenting and sharing experiences like these—whether they highlight challenges or successes—helps everyone improve. Lessons learned aren’t about pointing fingers or dwelling on what went wrong; they’re about finding better ways to work going forward.

    By openly discussing mistakes and successes, we:

    • Improve Performance. We can fine-tune our processes to be more efficient.
    • Reduce Risks. Identifying potential pitfalls early helps us avoid them.
    • Promote Collaboration. Sharing knowledge strengthens the team as a whole.
    • Retain Knowledge. Documenting lessons means that valuable insights aren’t lost if team members move on.

    Overcoming Challenges

    Admittedly, documenting lessons learned can be challenging. Time constraints, tight deadlines, or even a workplace culture that prioritises speed over reflection can get in the way. But taking the time to capture and review these insights is invaluable. In the case of shared coordinates, failing to reflect on misalignments could lead to repeated errors across multiple projects, costing time and resources. However, by documenting these issues, we can ensure they are avoided in future projects.

    Building a Culture of Continuous Improvement

    Embracing lessons learned fosters a culture where continuous improvement is the norm. It encourages everyone to:

    • Share Experiences. Both good and bad, so that others can learn.
    • Ask Questions. If something isn’t clear, it’s better to ask than to assume.
    • Be Open to Change. Sometimes the old way isn’t the best way.

    Lessons learned are a vital part of professional growth and project success. They not only help us avoid repeating mistakes but also enable us to build on our successes. The example of mastering shared coordinates in Revit illustrates how even technical challenges can serve as broader lessons in communication, planning, and teamwork.

    Don’t shy away from discussing what didn’t work. Instead, use those experiences as stepping stones to improve your processes and deliver better results.

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