# BoundingBox Intersection

Hello everybody!

I am working on a complex graph but it all comes down to a problem regarding the BoundingBox.intersection node.

Why does this node create an Intersection BoundingBox from 2 BoundingBoxes that are not intersecting?

To ilustrate the problem I have created a simple graph. In the following graph I have filtered out two different wall types and created a BoundingBox for all the examples of the two wall types. I use the BoundingBox.Intersection node to find were those two wall types Intersect. Even though the walls do not intersect, this node creates a BoundingBox in the origin point (from x,y,z = 0 to x,y,z =1). To illustrate it, I created a cuboid out of the BoundingBox.

Why is that? Is that how this node is supposed to work? Why doesnt it show an empty list?

are your walls orthogonal? Boundingboxes are incorrect if they are not. Only the middle wall is orthogonal in my case, the orange boxes are bounding boxes

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The walls in this example are not orthogonal. I know about the problem with BoundingBoxes and non-orthogonal walls, but in this case it doesn’t matter. The walls and their BoundingBoxes are not intersecting at all, but the BoundingBox.intersect node creates a BoundingBox in the origin point nevertheless.

Interesting. It looks like this is an issue with the intersection node. If there is no intersection, Dynamo returns a bounding box from [0,0,0] to [1,1,1].

Convert your bounding boxes to solids first, then check the intersection. That will give you what you want.

Which nodes does that?

Something like this maybe?
it gets the geometry of intersecting geometry of a wall with other walls:

Maybe a better option would be to pre-filter all intersecting nodes with `BoundingBox.Intersects` and only then calculate the intersection itself with `BoundingBox.Intersection`

Definitely. Forgot BoundingBox has an Intersects node.
Check for intersection first. > Filter elements. > Then get intersection.

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