3D Diff®

Table of Contents

Model Change Management with 3D Diff®

In this article, you will learn the principles of Model Change Management in 3D Repo and we will cover the basics of:

  • How 3D Diff works
  • How to use 3D Diff on a model
  • How to use 3D Diff on Federated models

How 3D Diff works

3D Diff is a simple to use tool designed to help you track changes across any model revision.
The real benefit is that you can detect geometric changes in 3D Models regardless of their file type or underlying data structure.
Model comparison is based solely on geometry and missing object IDs are no longer a problem.
As a result, you can run model comparison across any file format, here is an example:

  • Revit vs IFC
  • IFC vs DGN
  • IFC vs Navisworks
  • Any combination you like

Comparison Results are easy to comprehend and as following:

  • Green for new geometry
  • Red for deleted geometry

Below is an example scenario of how you would use 3D Diff to track model changes:

  1. We have received the initial model revision “Revision 1”
  2. Later on, we have received a new model revision with some changes “Revision 2”
  3. Using 3D Diff we can capture those changes and see their exact locations

Model Revisions


3D Diff Comparison results

Model setup for 3D Diff

3D Diff works across model revisions (Not different models).
If you want to compare several files you need to upload them to 3D Repo into a single model container but as separate model revisions.


Let’s take a look at the structural model in our project.
Currently, our model container holds 5 revisions (versions) of the model.
Each revision may contain design changes & be of a different file format.
Click on the revisions to see what they are.

Revision table will contain the following information:

  1. Revision name
  2. Username of a person who has uploaded the revision
  3. Revision description (optional information)
  4. The file format of the model
  5. Date & Time model uploaded
  6. Revision Status:
    1. If a model is Active it will appear in the list of revisions for 3D Diff
    2. If a model is Inactive it will not appear in the list of revisions for 3D Diff
      Use this option if you accidentally upload a wrong model revision (revisions can’t be deleted in 3D Repo)

How to use 3D Diff on a model

3D Diff is easy to you use and you can activate it in a few simple steps as shown below:

  • Open a model you want to check for revision changes
  • Open Compare Card in the features panel
    1. Select the 3D Diff Panel
    2. Select the model you want to check with 3D Diff
    3. Click on the drop-down menu to select any model revision you want to compare
    4. Click on the Green button to start the Diff
  • When you activate 3D Diff you will get the results in
    • green for new geometry
    • red for deleted geometry
  • Toggle between the Base & Target Models to understand model changes
    • Base Model (current model revision)
    • Target Model (selected model revision from a drop-down menu)
  • Deactivate 3D Diff by clicking the Orange button as shown below

By default, when you open a model container your base model is the latest model revision which you compare to any other model revision.
If for any reason you want to use other model revision as your base model, just open the model revisions table and open the desired model from there.

How to use 3D Diff on Federated models

There is no difference between using 3D Diff on a single model & federated model, other than the list of available models to Diff.
Since the federated model contains multiple files you get a longer list of models to choose from.
Essentially you have the following options when diffing a federated model:

Option 1

Run 3D Diff on individual models by selecting the one you want from the list.
3D Diff will isolate the model you have selected and run the comparison between 2 revisions

Option 2

Run a comparison of multiple models simultaneously.
This may enhance your visual understanding of certain geometric changes as they may be driven by changes in other models

Option 3

In some cases, when you run a comparison check on a single model you may lack some context to comprehend the reason behind some model changes.
This can be fixed by introducing additional models without comparing them.
All you have to do is select them in a list, but compare them to its current revision.
In the example below, we are comparing the MEP model only and showing the rest for context