Model Compare

Our model compare tool also allows for property comparison and determines if an object has changed based on a nominated ID. The tool is exposed to BIMFlow, which allows overnight batch comparisons to be run so the results can be stored in a database file and used at a later time.


  • An nVidia video card supporting compute 2.0 or above. List of supported cards can be found here.
  • Microsoft Visual 2013 C++ runtime available here.
  • nVidia Driver version 340.29 or higher


Model Compare reads the geometry from 2 models and compares the models for differences. Objects are categorized into 4 sets:

  • Matching – the object geometry is identical (Yellow)
  • New – the items are in the second model, not the first (Cyan)
  • Deleted – items in the first model which have no possible matches in the second (Red)
  • Unmatched – items in the first model that have one or more possible matches (other items with the same centroid) but which after comparing have no exact matches (Magenta)
  • Changed – if ‘Detect Changes Based on Unique Id’ is ticked, objects from New, Deleted and Unmatched that share the unique id will be moved into this set.

There are a few options for model comparison – the algorithm is biased towards false negatives rather than false positives, so objects that appear the same may by categorized as unmatched. This can be fine-tuned using the options. Due to the nature of floating-point operations this is something than can be limited but not eradicated. Interpret the results accordingly.



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