IFC Diff icon

IFC Diff

Compare different versions of IFC files, for documentation see Ifcopenshell.

Compare IFC Files

AI-generated

Overview

This node compares two versions of IFC (Industry Foundation Classes) files to identify differences between them. It is useful in scenarios where users need to track changes in building information models, such as architectural revisions or construction updates. For example, it can compare an old IFC file with a new one to generate a detailed difference report highlighting changes in geometry, attributes, classifications, and other relationships.

Use Case Examples

  1. Comparing two IFC files to detect changes in building elements before and after a renovation.
  2. Generating a difference report between two versions of a structural model to verify updates.

Properties

Name Meaning
Old File Name or ID Select the old IFC file from available files or specify an ID to use as the baseline for comparison.
New File Name or ID Select the new IFC file from available files or specify an ID to compare against the old file.
Output File Name of the output file where the comparison report will be saved.
Relationships Select which types of relationships to compare between the IFC files, such as geometry, attributes, classifications, etc. Excluding geometry can speed up the comparison.
Is Shallow Whether to stop comparison after the first difference is found for an element.
Filter Elements Optional IFC query to filter elements for comparison using IfcOpenShell selector syntax (e.g., IfcWall, IfcBeam).
Wait for Completion Whether to wait for the comparison job to complete before continuing the workflow.
Polling Interval (Seconds) How often to check the job status if waiting for completion.
Timeout (Seconds) Maximum time to wait for job completion in seconds.

Output

JSON

  • job_id - Identifier of the comparison job.
  • status - Current status of the comparison job.
  • result - Comparison result data, including differences found between the IFC files.

Dependencies

  • An API key credential for the IFC Pipeline API to perform file comparison and job status polling.

Troubleshooting

  • Ensure the selected IFC files exist and are accessible; errors may occur if files are missing or IDs are incorrect.
  • If the job does not complete within the timeout period, increase the timeout or check the API service status.
  • If the comparison is slow, consider excluding geometry from the relationships to compare.
  • Common error messages include network or authentication errors when calling the IFC Pipeline API; verify API credentials and connectivity.

Links

  • IfcOpenShell Selector Syntax - Documentation for filtering IFC elements using selector syntax, useful for the Filter Elements property.
  • n8n Expressions - Guide on using expressions in n8n to specify dynamic values for properties like file IDs.

Discussion