Revit Plugin - Dfjson vs Hbjson

Hello,

I did not see documentation in the forum or on the Pollination webpage/user manual. What are the relative strengths of using dfjson v hbjson export formats? Both seem to result in hbjson when opened in Rhino.

Best,
Victor

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Hi @victorbrac! This is a great question and I try to answer it in the context of the Revit plugin. There is a longer answer which is about how the Schemas are designed. You can read more about the two Schema on GitHub.

HBJSON (AKA Honeybee schema): Home · ladybug-tools/honeybee-schema Wiki · GitHub, 1.1 Model Schema · ladybug-tools/honeybee-schema Wiki · GitHub
DFJSON (AKA Dragonfly schema): Home · ladybug-tools/dragonfly-schema Wiki · GitHub, 1.1 Model Schema · ladybug-tools/dragonfly-schema Wiki · GitHub

The HBJSON format is designed to describe a detailed model with flexibility in geometry. Dragonfly is designed to describe an extruded geometry only. We originally developed the Dragonfly schema for urban-scale studies where the models are simplified but then we realized that it can have more use cases such as exporting simplified models from Revit.

If all your rooms are extruded the output of both methodologies should look the same but it will be different if there are tilted walls and roofs. Here is an example.

The other difference is how the Revit plugin tries to calculate the geometries between the two methods. The HBJSON path tries to export the detailed geometry but the DFJSON method extrudes the boundary of the room.

That means that for a clean DFJSON model you only need to take care of cleaning up the room boundary which can be handy in larger models when all the geometry are actually extruded geometry. It is also easier to get a clean model. That said if you want an accurate detailed representation of the geometry you have to use the HBJSON workflow.

There are other differences in what you can control during the export process between the two but I hope this reply is good enough to clarify the main differences. Let me know if you have any other questions and I will be happy to reply. I’m sure that @chriswmackey can provide a better and more comprehensive answer to this question.

Finally, in the upcoming release of the Revit plugin, we are renaming the DFJSON vs HBJSON method to Extruded vs Detailed to make the differences clearer.

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Just to clarify from your screenshot; would there still be rooms defined in the DF model?

Yes! Both of the schemas share the concept of a room, and that’s how we can translate one to other.

The object in Dragonfly is called Room2D. You can read more here:

image