Create a parameter called "IsExternal" for exterior or interior position

[Maria Calogeropulos]

Hi!

We have a klient that wants to have a parameter in the ifc export that is called "IsExternal" and gives a response as "True" or "False" if the object has a position as "Exterior" or "Interior".

I have tried to do this, but I don't get how to do it. 

Can you help me?

Kind regards,

Maria

[Karl Ottenstein]

Here is one possible way, assuming that the information is wanted to distinguish just objects that are either inside or outside the building...

Create a zone that covers all outside areas (patios, public spaces, etc).  Select the zone, and with the zone tool active, magic wand the outside of the building to cut a hole so that the zone only covers the external area.  Name the zone Exterior.

Then, create a new property with a property expression as shown here, which will be True if an object/element is contained in this Exterior zone and False otherwise.

 

Note that the expression will not be evaluated when you simply look at an object's setings (it will read as <expression>).   But, to test, you can create a schedule and schedule this new IsExterior property to verify that it is showing the desired result.

This is all a bit new to me, so perhaps someone more experienced with property expressions has a better method.

PS The reason for cutting a hole for the building, is that various issues arise when you have overlapping zones and there will no doubt already be zones for the interior of the building.  Presumably this would be the only Exterior zone and would not overlap any other zones.

[Mathias Jonathan]

I think that this ifc parameter is directly exported when you assign the external/internal parameter (by default: non defined) that is accessible out of the box for each Archicad object.

If you use one of the included ifc traductor, it should be automatic.

[Laszlo Nagy]

Here is how to do it:

1. Go to the IFC Translator Dialog.
2. Click the Ellipsis button (...) to the right of the Property Mapping field.
3. Create a new Preset so you will not modify the default Presets.
4. Go to the "Map IFC Properties for Export" Dialog.
5. Select "IfcElement" on the left, and click the "New" button at the bottom. Create a custom IFC Property: set its Set Name and Name ("IsExternal"), its Type is "Single Value", its Value Type is "IfcLabel".
6. Click the "New Rule" button to create a new mapping rule.
7. Click the "Add Content" button and select the "Position" General Property (it is in the "General " group. Click OK.
8. When exporting as IFC, make sure that the IFC Translator you use is using the Property Mapping Preset that you created because this custom IFC Property and its mapping Rule exists only in that Preset.

[Laszlo Nagy]

The previous post shows how you can directly map the value of the Position parameter to a custom IFC Property.

In your case, this is not the intended result since you want the value of the "IsExternal" custom IFC Property to be "True", "False", or "Undefined", depending on the value of the "Position" Global Parameter. To do this, you can create a Property in the Property Manager with the following Expression and map that to the "IsExternal" custom IFC Property. (Make sure the Property's Data Type is "String" and it is available for all Classifications.

[Laszlo Nagy]

Please note that when you select an element and go to its Settings Dialog, you will see the Position parameter, the Property you created, and the custom IFC Property you created.

Since the Property is defined by an Expression, the custom IFC Property does not show its value. I don't know if it is because the value of the Property is not evaluated or for some other reason.

[Laszlo Nagy]

However, if you activate the IFC Project Manager Dialog you will see that the value of the custom IFC Property is evaluated and correctly displayed. (Just make sure the correct IFC Translator with the correct Property Mapping Preset is selected before entering the IFC Project Manager - remember, this custom IFC Property and its mapping exist only in that Property Mapping Preset.

[Laszlo Nagy]

And checking in Solibri shows that the custom IFC Property is correctly created and displays the correct value.

[Karl Ottenstein]

This works if the Position parameter has been defined properly for every object.  If an exterior object has Position set to Interior, then it will not have a True value for IsExterior.  The zone method I presented would catch that (and could even be used to audit and find errors in the value of "Position" ... but as I said earlier, it will not catch everything.  For example, an exterior light fixture in a wall niche would not be caught with the zone method.

EDIT: Actually, ignore my first and this post. 🙂 I'll leave them  vs delete them since it might be useful to someone to see that my zone method really doesn't work either for defining the property - or for auditing.

Given that 'exterior' objects or elements may also be on roofs, balconies, etc etc., a zone approach to automatically identify them would be unrealistic to construct - potentially a complex 3D zone that would still accidentally touch or not touch some elements.

Using the Position value that Laszlo shows does make the most sense, even though the value of Position can be wrong.  But, that value could be audited and corrected with a visual edit using a Graphic Override.

[Laszlo Nagy]

Hi Karl,

I think you and I are talking about two different things.

Maria talks about objects.

In Archicad, an entity you place or create is called an "element", and "Object" is an element type.

In some other CAD/BIM applications, an entity you place or create is called an "object".

If I understand correctly, your assumption is that when she writes "object" she means Archicad elements created with the Object Tool. And your assumption is that she wants this IFC Property to reflect whether an Object-type element is outside or inside the boundaries of the building. Your solution work well to address that scenario.

My assumption is that when she says "object" she means any Archicad element. And that by "Position" she means the "Position" parameter of elements available in the "Classification and Properties" panel of element settings dialogs. My posts provide a solution based on that assumption.

So it is now up to Maria to tell us which one was her original purpose. 😀