IFC Change Management

Note: Since Tekla Structures 2016, this tool is replaced by the IFC change detection feature available in Tekla Structures. See Detect changes between reference model versions.

1. Purpose and description

Compare any two IFC models to find differences between model revisions.

This IFC Change Management tool in coordination with Tekla Structures unique IFC Reference model technology and the Tekla IFC object converter allows project team members to visually inspect the modifications, deletions and additions of materials between two different IFC format models in Tekla Structures at any time.

The user can control which properties stored in the IFC file they want to compare, such as profile, material grade, length, piece marks, rebar properties etc. Project team members can then get printed reports showing the description of the changes on those parts and properties that are different for submission of change orders to other project participants and the owner.

Since these changes are automatically being detected and reported in the 3D environment, costly delays and rework caused by days of manually processing change orders from 2D drawings can be greatly reduced thus bringing savings to all of the project participants and the owner.

The change management tool supplements the workflow of absorbing changes between project team members, where changes are first studied, then absorbed into the model. New objects are converted from reference models into native Tekla objects using the IFC Converter. Once converted, these native objects can be later updated to the current properties through the IFC Change Management tool.
 

1. IFC Change Management: Internal Workflow
   
   
   
   This video shows how IFC files can be used internally to track differences between revisions and/or design changes. For example the user could create an IFC file as a snap shot of the current state of the model. They could then make the needed design changes and then create another IFC snapshot of the new state of the model. Those can then be compared and a report can be generated of any and all changes.


2. IFC Change Management: Engineer to Detailer 1
   
   
   
   This video shows the workflow of how a detailer can use an IFC file that they receive from an engineer to begin their detailing model. The detailer would insert the IFC file, convert to native objects and then begin detailing the project. If/when they receive and updated or revised IFC file they can then compare that with the original file to see what’s new, modified or deleted. Since the detailing model originated from the IFC file they can even update the native members from the new IFC file to incorporate the changes.


3. IFC Change Management: Engineer to Detailer 2
   
   
   
   This video shows how a detailer that has already started the creation of their model can use an IFC file for comparison purposes if they receive an IFC file at any stage in the project. Since the model did not originate from an IFC file the detailer can use the IFC Change Management extension to build a bridge between the IFC file and the native members so that a comparison can be done. Once this bridge is built they can continue to receive and compare IFC files to view what’s new, modified or deleted.

2. System requirements

Tekla Structures configuration: Any

Environments: Any

3. Installation and launch

To install and launch the extension:

1. Download and launch the appropriate 32bit or 64bit (x64) IFC Change Management installer. The installer will automatically detect your environment and install toolbars and files to the appropriate folders.

2. Restart Tekla Structures. On certain environments, a new toolbar with an icon should appear in the user interface. If not, follow the steps below.

   Note: The toolbar is user (ie, Windows user account) specific; which means that the user installing the extension would get the user toolbar in Tekla Structures and another user would not.

   To manually add the extension to a user toolbar in Tekla Structures:

   1. Click Tools > Customize to open the Customize dialog box.

   2. On the Toolbars tab, click “New....”. A new toolbar with the name “User Toolbar 1” appears in the toolbar tree. You can enter a new name for the toolbar.

   3. Search for the extension on the list on the left, click on it and then click the right arrow to add it to the toolbar.

   4. Click Close.

4. Making a new comparison

When launching the tool, you are presented with the New Comparison dialog. The Original Model and New Model drop-down boxes contains all the IFC models found in the current model root folder. If you wish to pick models from somewhere else in the file system, you can press the [...] buttons on the right hand side of the fields. Additionally you can get a reference model directly from the open Tekla Structures model by selecting it in the view and pressing Get.

4.1. Property and filter setup

On the Property Setup tab you can modify IFC object properties that will be compared. Properties can be prefixed with e.g. Tekla Common or similar, which is used when retrieving the property value from the ifc objects. When retireving the corresponding property value from the native object in the model, the prefix will be stripped.

Some default properties are shown when you launch the tool. You can add new properties with the Insert a new property button and write the property name on the new row. Alternatively you can inquire a reference object in the model and copy one or several rows from the inquire dialog with Ctrl+C, and then add them to the list with the Paste button.

The tick box in the E column determines if the property will be included in the comparison or not.

The tick box in the U column determines if the property will be used to update native parts (you can set this later in the main window as well). White tick boxes means that the tool will create or update a native object UDA with the same name (any prefixes will be stripped). In some cases the actual property of the object can be updated rather than just an UDA. These properties are indicated with green tick boxes and include Profile, Name, Class, Material, Finish, START_X, START_Y, START_Z, END_X, END_Y, END_Z.

Per default the properties that are retrieved from and updated for the native objects have the same name as the IFC property (with any prefix stripped). To override this, the Map to Native Property column can be used to create a custom mapping to any other native property or UDA.

On the Exclude Filters tab you can exclude certain IFC objects from the comparison if they have any of the property values in the list.

Property and filter lists can be saved to a file and then used as a preset.

4.2. Executing the comparison

Once you have selected two models and checked the properties and filters, press Compare. Any IFC models that are not already inserted in the model will be inserted automatically at origo (0, 0, 0). Hidden models will be shown and unsubdivided models will get subdivided. The models will then be compared part by part according to the property and filter rules you’ve set up.

When complete, the application shows a list of changed parts. Additionally a text report summary is created that shows how many objects are modified, added or deleted.

A new view will get created in the model that shows the IFC models that are being compared on top of each other. Changed parts are color coded. The main view changes representation as well.

5. Studying the results

The application shows a list of all changed (new, modified or deleted) parts that were found in the comparison. If you select a part from the list it is highlighted in the model, and the old and new property values for that part are shown in the application. If a native part is found that matches the reference object’s GUID it is highlighted and the native values are shown as well. If a native part isn’t detected yet you can manually link native parts to the reference parts with the Link Objects in Model… button.

If you select one or several reference parts directly in the model they will get highlighted in the list.

Double-click a row to zoom in on that part in the model, or select one or several rows and press the Zoom button.

The part list can be filtered by selecting parts/rows and clicking Show Selected Only. You can remove rows altogether by using the red X button.

6. Resolving changes

New reference objects (color coded green) can be selected and then converted with the IFC Object Converter through the Tekla Structures menu Tools > Convert IFC Objects.

Modified and deleted parts in the reference models can be used to update the native model. Select the row or reference part that includes the changes and press Convert Native Parts. Properties that are checked in the U tick box column will get updated for the native part, but only if they have been changed between the two reference models. So a native object property that has a different value from the reference object property will not be updated if there hasn't been a change between the old and new reference object value. Green tick boxes means that the actual property can and will be updated, white means that an UDA will be updated.

The Native Part column in the part list will show if the update was successful or not. You can then select the row to view the new native values in the properties list.

As you review changes you can set the status of each changed part in the Status column in the part list. To change the status of multiple rows at once, first select multiple rows with the Shift or Ctrl key, and while still holding down the key click the status combo box of the last selected row.

7. Saving and exporting comparisons

You can save the current comparison from the Save menu. This will remember the remaining comparison rows with their current status, and the filters and property sets used. The comparison can then be restored by clicking the Load button.

You can export a detailed list of the changed parts and properties to Excel or to a txt file from the Save menu by selecting Export.

By using the Object Browser template located in the installation package (“IFCChangeManagement.xml”) you can view and report on the changes in the Object Browser as well. To do this, launch Object Browser, import and select the IFCChangeManagement.xml template and select the parts you wish to view in the IFC Change Management part list. In newer versions of the tool the template is available after the installation without importing.