The previous article MODEL COMPARISON – SOL/206 provides a detailed introductory explanation on how to compare two versions of a model. In this article, we focus on tips to partition model comparison checks into more granular pieces, namely results of what components have been added/removed and how they have been modified in terms of their identifiers, quantities, locations, and property sets.
You can follow along with this article using the example file available through the link below:
The example linked above was modified using the same IFC files and ruleset from the previous “MODEL COMPARISON – SOL/206” article. The image below shows which rules have been added based on the specific type of comparison to be checked:
After running the check for the “Component Comparison” rule, then expanding those results, you’ll find Added and Removed components listed first as a category of results:
These Added and Removed results will always be listed if found, and if running checks for other properties, they are listed first before the category of what has been modified. If you wish to only see what components have been added/removed, you can simply uncheck all Compare checkboxes in Rule Parameters of the Model Comparison rule. You can see below in the rule parameters of Component Comparison – Only Added/Removed, all checkboxes have been unmarked and the results of the check no longer list any components that have been modified.
Next, we’ll look at the Modified results category and the Identifications checkbox parameter of the Model Comparison rule.
In the Results view, after selecting the “Component Comparison” rule, you’ll notice results with “Reported Property” listed last in the sub-category:
If you expand the result category “Door: Geometry, Location, Quantity, Reported Property [0/1]”, and select the result “(OLD) Door.0.11 – (NEW) Door.12”, you’ll see a listing of changes to the component in the Info view:
The last two listings in the Info view (highlighted in the image above) are properties from the Identification category, which was marked in the rule parameters. These Identification properties are the same as the properties listed in the Identification tab of the Info view after selecting a component. In this result, the single swing door in the old file was swapped out for a double door in the new file. This explains why the Type and Operation parameters are listed as being changed. The other listings of changes pertain to the geometry, quantity properties, and location properties. If you are only interested in the changes of Identification properties, you can leave only that checkbox marked in the rule parameters of the Model Comparison rule.
Notice there are fewer results listed in the Results view to review and the information regarding the change to the door only pertains to identification properties.
Notice again that the Added and Removed categories are still listed in the Results view. The Compare checkboxes in the rule parameter only determine what will be listed under the Modified category. If a component is added or removed in the model, it will always be listed regardless of what checkboxes are marked.
When the geometry of a component has changed, it will likely cause a change in the location properties and quantity properties of the component as well. Notice in the image titled “Component Comparison – Door Results and Info Views”, that the Global X property has changed. Since the double door is now larger, its Global X location property has shifted along the wall. Also, its Area, Width, and Frame Length quantity properties are larger as well.
The Location of an object can change without its geometry changing by simply moving it. In the image below, you can see the four sinks in the model were raised by 20 mm, though their geometry remains the same:
Lastly, you may wish to only monitor changes in a specific property or set of properties. For example, many IFC components such as doors and walls have common properties such as Fire Rating. These are found under a property set named Pset_DoorCommon and Pset_WallCommon respectively.
In the rule PSET Common Properties Comparison, the rule parameters have the Property Sets check box marked and the table is populated with all of the various common property sets in the Property Set Name column. The Property Name column contains an asterisk to denote that any property found under the property set is to be checked for changes.
In the Results view, we see that the Pset_SpaceCommon.GrossPlannedArea property has changed of a space.
You can create a Model Comparison rule to check for changes of properties of a specific use for the model. In the screenshot below, the property sets table is populated to check only those properties that pertain to COBie information for changes :
More information on COBie and SMC can be found through the link below: