The boundingbox is way off the Brep.
I don’t exspect a Minimum BoundingBox but even the “boxedit” finds the right XY-boundingbox.
I really don’t know why. It is an vlosed brep laying on XY-PLane
BoundingBoxWrong.gh (4.8 KB)
The problematic surface is the curved side surface, and the problem is limited to grasshopper - Rhino’s BoundingBox evaluates it correctly.
As a workaround, you could use DeBrep to extract the edges and BBox those together.
EDIT: you can also use this python script, but it requires a model object input:
import Rhino
rh_obj = Rhino.RhinoDoc.ActiveDoc.Objects.Find(Object.Id)
result, Box = Rhino.DocObjects.RhinoObject.GetTightBoundingBox([rh_obj])
It’s a bug which occurs when the seam of the vertical surface coincides with certain knots on the perimeter. As a workaround you can move the seam.
This bug is not present in Rhino 6. Things have obviously gone downhill since…
In the meantime, I suppose you could find the union box of the BRep edges if the surfaces are planar.
RH-94035 is fixed in Rhino 8 Service Release 31