MEP Systems in BlenderBIM

Hi people,
yesterday I imported an HVAC system designed in Revit to BlenderBIM. All the geometry and most of the IfcClasses translated nicely, but it is lacking in IFC Object Property Sets. The property sets are loaded with properties, but their values are not correct(equal to zero). As seen in the image:
Obviously, that is an issue of the proprietary software that exported the model, but it is also an issue of BlenderBIM, since the geometry is not related to the values. I would like to try and work on improving the MEP system modeling, and since it seems there aren't many MEP guys around this could be a good place to deal with MEP related development in hope that it gains some traction.
Since I am new to BlenderBIM and not really experiencend in both python and overall IFC schema, I could use all the help I could think of. For starters, I downloaded the latest developer build so I can research it and figure it out as much as I can.



  • Maybe @Cyril can help you out? I am clueless about MEP engineering.

    He has made some cool stuff

  • Yeah, I am aware of the great work Cyril did in the pyRevitMEP package. Hope he finds time to help any way he can.
    In the meantime, I am trying to figure the authoring part from the developer build to see how I can approach the workflow appropriately. I think the code from your XML writer should also help.

  • @thunderbolt_132 there may be a misunderstanding here. In your red circle, the majority of properties are simply set to NULL (as denoted by the "Blue empty circle" icon). This means that those properties are not defined, and what you see there are simply the default values (hence you see 0 for working pressure for example). So I don't see the issue here.

    Or am I misunderstanding your issue?

  • edited January 10

    @Moult That is true, but my point was that as I change the NominalDiameterOrWidth and NominalHeight nothing happens, which means that my duct is not parametrically tied to the IFC values, and that is what I am hoping to achieve. If I got it correctly, the NominalDiameterOrWidth and NominalHeight are the parametes that dictate the size of the duct (equivalent to Width and Height in Revit).
    From your more experienced point of view, could you briefly write how you would generally approach the developement of these systems? Just a very rough and high-level sketch could be useful, basically anything would help. There plenty of stuff to learn both in the coding and in the general IFC schema parts, so sometimes I feel I'm running in circles.

  • @thunderbolt_132 the attributes are not parametrically linked to the geometry by default. This is because there can be many different parametric interpretations of how to modify or generate geometry from these attributes. The "Revit" parametric duct generator might be what you're looking for, or you might want a different duct generator. So when you are within "Revit", they might indeed be linked, but outside Revit, the link is broken (for now). IFC allows, but does not enforce, a parametric link.

    Linking attributes to parametric geometry is possible, but we are tackling it on a case by case basis (someone has to write the ACME Duct Generator V1.0). Revit's parametric behaviour is specific to Revit. In the future, we may recreate Revit's parametric behaviour as an option, and keep this parametric behaviour. In the future, other parametric ducts might also appear that follow different rules. But this is still on the roadmap, especially as MEP in the BlenderBIM Add-on barely exists right now.

Sign In or Register to comment.