Boundary Edges#

Description#

A boundary edge is an edge that is shared by only one face (instead of the normal two faces in a closed mesh). Boundary edges can be intentional, for example a floating surface representing a furniture inside the room. However, unintentional boundary edges indicate that the mesh is not watertight and may have holes or missing faces.

Detection#

Detection Method: Edge degree counting

Algorithm:

  1. Build a complete edge map from all faces

  2. For each edge, count how many faces share it

  3. Flag edges with degree ≠ 2 as boundary edges - Degree 1 = boundary edge (open to outside) - Degree 0 = unused edge (orphaned) - Degree > 2 = non-manifold (multiple disconnected shells meeting)

Auto-Repair#

Status: ❌ No automatic repair

Action: Detection and reporting only

Manual Fix / Avoidance#

In CAD (Before Export):

  1. Determine if intentional: - In Blender we can: Enter Edit Mode, then use “Select > Select All by Trait > Non-Manifold” - In Non-Manifold select “Turn on Boundaries” to see edges that are not connected properly