How to export instances to separate layers of a 3D DWG?

[a.ghensi689507]

Hi all,
My firm is working on a project using revit (I's mainly a civil engineering project but we use revit as starting point for our BIM workflow), and one of the client requests is to have the 3D model in DWG, putting every object/instance in separate layers named with the family name/type and instance ID.
Is it possible to do that with revit? I don't see any layer mapping modifier that could help me getting what I want.

thanks for the attention!

[barthbradley]

Export=>CAD=>DWG=>"..." (Export Setup)

[Dimitri Harvalias]

So they want all that information included in the layer name? And every instance would have its own layer? That sounds incredibly cumbersome. I can't imagine what working on that CAD file would be like.
As you have already found out, nothing out of the box that would allow that kind of garanularity. I'd suggest that you might want to get a custom LISP routine written that might be able to do it on the ACAD end?

[a.ghensi689507]

Thanks for the answers.
The client's requirements tell us to put every object on a separate layer of a 3D DWG model, and to follow their tagging/coding guidelines.
So the plan is to put that tag on the istance comments (or another property) and use it somehow to create the desired DWG 3D model.
I'm the macro developer of the company, and I just tried to see if there's a way for me to avoid some of the work.
I guess I'll have to develop a macro to export every single object on a separate dwg (named as the tag stored in the property) and then combine them all in a single DWG model.


EDIT: I found a way to solve this problem! Revit exports the ElementID inside the XData of the autocad element, so I need to create a macro that saves the ElementID and the tag/code of the element into a xls/csv file, export the 3d view, then create a VBA macro in autocad/excel that reads the ElementID in the XData and creates the layer named after the tag (found by looking into the CSV file).

[david_peterson]

Dumb question, but for some reason I seem to remember there was a limit to the number of unique layers you could have in an autocad file?
I believe it's a high number, but depending on what your exporting, I could see a lot more objects in a revit model than the number of layers allowed.

[jsnyder.68308]

AutoCAD's MAXSORT system variable goes to 32767. That is a lot of layers (at least 32700 more than I would want to deal with), but I doubt its enough for a Revit model of any size.

[david_peterson]

And that was kind of my point.
I'm not sure the client really understands what they are asking for, unless it's a parts model.
I couldn't imagine doing this for a building.