Multiple active sections


I’m after advice about how best to use two or more active sections at once. I know that you can do it providing sections are inside a group.

Here’s the scenario: You have a building with several floors. You have created sections outside any group to show each floor. But where you have openings in floors, things on the next level can be seen. You might want to hide them for clarity. I know you can achieve that by hiding groups but I suspect it is also possible by using sections, maybe with one looking up and the other down.

Any advice on this common problem?

Hi @simoncbevans, I use the two section method regularly for situations that you describe. The “up” looking section I also utilize for reflected ceiling plans. Best.

if my model is going to be displayed via LayOut, i’ll use LO masking to hide things, this simplifies the sections layout in SU (at least for me). or as @Lindsey noted - an RCP (perhaps defined by a section external to the group) and another vertical section inside the group? or perhaps they both need to be in the group?.

An additional note, for a two scheme section to work, both sections need to be active, therefore they must reside within two different groups/components (three active sections would require three groups/components & etc).

My modeling, 99% of the time, does not require more than two active sections. So I normally utilize the “modeling environment” for one set of sections and a “Section Group” surrounding the entire model, for the second set of “partner” sections.

I have just used the two section system. They don’t both have to be inside groups in fact but only one can be outside.

Depending on what your background is and how you deal with it, another possible approach is an actual face object placed where you would put that far section. If it’s opaque, it will hide anything beyond that plane from view. You could also make it semi-transparent to let something show through, but muted somewhat. That would be similar to how Sonder uses Fog so much to isolate depth, but the effect would be abrupt at that plane instead of gradual with depth. You won’t get a transparent background in LO if you go that way though.

proof of concept:

Two big (nested) boxes that hold several sections. You need some geometry to constrain the section cuts.

twosections.skp (314,5 KB)


In my job (civil engineering and reinforced concrete draftsman
Export.pdf (887.6 KB)
) we have to make different plans from the architect’s plans and also have to manage the lines behind the elevations of the walls or slabs.

_Section Plane
_Section Plane_back

The method I use is:

Level 1 (Root):
(group) “Level 2”


Level 2:

(group) Building


Level 3:
(group) First Floor
(group) Second Floor
(group) Third Floor



This method allows me to have the front and back section plane that intersects ALL the model

Skalp is used on the front section plane because it needs to be at the root to work and I enable the back section plane to sandwich my building so I don’t have the dashes running the full depth of the building but only about 50 cm.

In Layout, the layers are as follows in order:

  • Symbols and texts and dimensions
  • Dashed walls
  • Skalp Cut Walls

The lines superimposed on the cut walls or lines of sight are not visible and only the visibility of the back walls of the elevation remains.