Change Detection

The Detect IFC Model Changes function (File > Interoperability > IFC) detects the geometric differences between two versions of a single model that has been exported as IFC – that is, it compares two IFC files that are two versions of the same project. The elements affected by the modifications are generated and merged into the currently running project (that project can also be an empty one). Modifications can be viewed and managed using ARCHICAD’s Mark-Up tool in both 2D and 3D views.
New Elements: elements created in the newer version that did not exist in the earlier version.
Deleted Elements: elements that existed in the earlier version but were deleted from the newer version.
Modified Elements: elements that have been modified (in their position and/or size) from one version to the next.
It is important that the two IFC files being compared originate from a single application and a single project, because the comparison process (more specifically, the pairing of the modified elements) is based upon the elements’ GlobalId numbers in the IFC model. If there are no identical IFC GlobalIds in the two versions, then all elements will be considered either new or deleted.
See Export Options of IFC Translators.
Filtering by IFC Domain: use one of the predefined domain filters to define the element types to be compared. The default value here is the IFC Domain (Import/Export Filter Options) setting of the translator chosen above. “All element types” will compare all elements from the two files. The “Structural” or “HVAC” domains will consider only IfcBuildingElements (IfcWall, IfcBeam, IfcSlab etc.) or IfcDistributionElements, respectively. The “Custom” domain filter can be created using the Options button – e.g., you can consider just beams (IfcBeam) or just columns (IfcColumn).
Filtering by Structural Function: if the IFC files to be compared include elements classified by Structural Function (that is, LoadBearing IFC Property is assigned to elements), then use this setting to filter load-bearing elements, for example as part of a structural-architectural data exchange. The default value here is the Structural function (Import/Export Filter Options) setting of the translator chosen above.
Note: You should use this filtering option only if you are certain that your fellow professional, with whom you are exchanging data, is using and able to export the LoadBearing IFC Property.
Filtering by Story/Layer/Owner/Element type: the elements of the two files are listed in a tree structure under (IFC) Element Type. The initial filtering is carried out by the IFC Domain and Structural Function filters set above; this part of the dialog box enables further fine-tuning of the filter, by checking or unchecking element types one by one. Elements can be grouped in this structure, to make it easier to gain an overview. For example, you can group the element types by Story, by Layer, or by both Story and Layer. For example, you can combine an element filter with a story filter to compare just columns on the floor plan.
Hint: The default colors for marking different change types can be modified in the Mark-Up Styles palette (Options > Element Attributes).
Deleted Element: You can leave it in as part of the project (placing it on a separate layer); or you can delete it together with its Mark-Up Entry, by clicking “Delete Entry” in the Mark-Up Palette. You can also use “Delete Entry” without deleting the elements in the Entry.
New Element: Since it has a Highlighted status, deleting its entry will not delete the element, it will just lose its Highlighted status. Then you can use the element as you wish (or even delete it from the project). A New element will be deleted together with its Mark-Up Entry only if you first remove its Highlighted status (click the “Remove Highlight” button).
Modified Element: This pair of elements includes one each that is “Old” and “New”, with the same options as described above for “Deleted” and “New” elements. That is, if you do a Delete Entry, the older-version element can be either retained or deleted, while the newer-version element will remain intact, while losing its Highlighted status.
Hint: If you delete a Mark-Up Entry by mistake, use Undo.
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