How to preserve component/tag when draping polylines over topography?

I am creating a 3D model of my school’s campus, and I have a topographical surface representing the terrain. I am importing polylines as .dwg files from AutoCAD, and they come in as separate components, but once I drape them over the topography, they become part of the terrain, and they don’t stay as a separate entity. The reason I would like to have them all as separate tags is because it can make it easier to render to final product by hiding certain layers if needed, as well as keeping it organized. Any help is appreciated, thank you!

It sounds to me as if they are not components but instead the edges have tags. This is common with imported .dwg files. Tags do not prevent geometry from merging. You need to use components and groups for that. The imported .dwg file should import as a component but if you explode it you will wind up with a bunch of loose geometry that will merge with other geometry it intersects.

Normal, correct practice is to have all edges and faces in the model untagged and give tags to groups and components in the model.

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I see, but is there a way to keep the polylines as a separate component while using the drape tool? My problem is that it just merges and you can’t really recover any organizational info from before.

The polylines should be getting copied onto the terrain so the originals should remain in place above the terrain.

Yes I know that, but is there a way to keep the original tags in the copied version that lays on the terrain?

No. The draped geometry is created untagged as it shouuld be. Again, geometry (edges and faces) should be untagged.

A couple of alternatives come to mind. One would be to create a copy of the terrain geometry to drape the polylines onto. Delete the faces leaving the draped polylines and create groups or components for each of them so you can assign the tags properly.

Instead of draping the edges you could first make a component or grou for each of the polylines and give the tags to those objects. Then use an extension called adebeo_pushline to extrude the polyline edges down through the terrain. Use Intersect Faces to replicated what Drape does, and then erase the everything but the draped polyline edges. The groups or components will retain their tags.

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You can!

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Ok makes sense, I’ll give it a try. Thanks!