Define a comparison set for reference model change detection

Tekla Structures
Tekla Structures

Define a comparison set for reference model change detection

Change detection in Tekla Structures compares different versions of the reference model based on a comparison set, which tells you whether Tekla Structures considers a change in a property a change or not. You can use the standard property comparison set, or define a comparison set of your own.

In the reference model, when change detection is active, the changes list shows all deleted, changed, new and not changed objects. The property details list only contains those properties that are defined by the current comparison set rules to be compared.

When you save a comparison file, both the standard file and a customized comparison set file are saved to the \attributes folder under model folder. The standard file can only be removed from model folder if it exists in another location. If saving or removing the standard file is not successful, you will get an error message.

The property set comparison tolerance setting files (.rmct) and the comparison set files (.rmcs) can be read from subfolders of the firm and project folders defined for the advanced options XS_PROJECT and XS_FIRM.

Create a new comparison set

  1. Open two versions of the same reference model.
  2. In Change detection, click the Comparison sets button ... to open the Comparison sets dialog box.
  3. Enter a name for the comparison set.

  4. Add a new comparison rule by clicking the Add row button and typing or copying and pasting the property name.
    • You can copy and paste property names directly from the property details list in change detection.
    • To include more properties within one rule, use asterisk (*), for example:

      X* (all that starts with X)

      *X (all that ends with X)

    • If you want to compare only one property set property, clear the Property sets check box and create a separate rule for that property. If you want to compare all property sets but not one property, select the Property sets check box and create rule for that property and leave its check box empty.
    • Note that comparison rules are case insensitive.
    • All rules in comparison set affect the comparison if the reference model version has a corresponding property.

  5. Add more rules in the same way as in step 2 and 3.
  6. To delete a rule, select the rule and click the Delete row button .
    You cannot delete fixed comparison rules, like Geometry, Location, Rotation, Materials, Profiles, Products, Common attributes or Property sets, but you can exclude those from comparison by leaving the check boxes next to them empty.
  7. Ensure that you have the check box selected next to all the comparison rules you want to include in the comparison set. If you do not want to include a rule, clear the check box.


    You can also exclude attributes already included in a property set by adding a separate row for that specific attribute and then ensuring that you do not add a check mark in the check box next to that specific attribute.

  8. Click the Save button .
  9. Close the comparison set dialog box by clicking the Close button .
    If you have not saved your changes, you will be asked if you want to keep the changes when you close the dialog box.
  10. Click the Update view button.

Properties in comparison set

A comparison set may contain the following types of properties:
  • Free property set properties, such as BaseQuantities.NetVolume
  • Fixed properties that always exist in the comparison set file, but can be excluded from the comparison

The fixed properties are listed below:

Property type Description
Geometry Object dimensions
Location The coordinates of the object in the model
Rotation The rotation coordinates of the object
Material Material name and grade
Profile Profile name

IfcProduct parameters that vary object type by type. Some properties are optional.

Below examples of product properties for IfcColumn:

Application full name

Application identifier

Change action

Creation date


Family name

Given name

Is set last modified date

Last modified date

Middle names


Object type

Organization description

Organization names

Organization roles




Common attributes

Below examples of common attributes for IfcColumn:

External Use

Fire Rating

Load bearing




Property sets

Whatever has been added to IFC properties.

Below examples of property set properties for IfcColumn:

BaseQuantities.Length [mm]

BaseQuantities.NetWeight [kg]

BaseQuantities.NetVolume [mm³]

BaseQuantities.OuterSurfaceArea [m²]

Tekla Common.Bottom elevation

Tekla Common.Class

Tekla Common.Phase

Tekla Common.Preliminary mark

Tekla Common.Top elevation

Tekla Quantity.Area per tons [m²]

Tekla Quantity.Gross footprint area [m²]

Tekla Quantity.Height [mm]

Tekla Quantity.Length [mm]

Tekla Quantity.Net surface area [m²]

Tekla Quantity.Weight [kg]

Tekla Quantity.Width [mm]

Tekla Quantity.Volume [mm³]

Define property comparison tolerances

In reference model version comparison, you can modify the property comparison tolerance settings to get relevant changes more easily. You need two versions from the same IFC model.

The changed row appears as light yellow if the tolerance is bigger than the difference.

  1. Open two versions of the same reference model.
  2. In the Reference Models pane, open the Change detection section and activate the change detection.
  3. Click the Property set comparison tolerances button .
  4. Change the tolerances by modifying the values.

  5. Apply the changes by closing the dialog box and clicking Update view.

    The changed row appears as light yellow.

    You can also save the tolerances in the Property set comparison tolerances dialog box.

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