Select Boundary Tris adds to the selection all triangles that lie on the boundary of a mesh, that is, triangles with at least one edge on a hole or an open border. Use it to find the holes and open borders of a scan or an imported model before you repair them. This guide also covers Select Boundary Edges, which selects the boundary edges themselves.
Select boundary triangles
- Select one mesh in the scene list.
- Click Select › Select Boundary Tris.
No panel opens: the boundary triangles are added to the current selection at once, and the Information panel shows how many triangles are selected.
The button is available only when exactly one mesh is selected and this mesh has holes. For a closed mesh it is grey, and its tooltip says "ObjectMesh doesn't have any holes".
Select Boundary Edges
Select Boundary Edges adds to the edge selection all boundary edges of a mesh, that is, edges that belong to only one triangle. Together they outline every hole and open border.
- Select one mesh with holes in the scene list.
- On the Select tab, open the drop-down arrow next to Select Boundary Tris and choose Select Boundary Edges.
The edges are added to the current edge selection and shown as colored lines. Like Select Boundary Tris, the command is unavailable for a mesh without holes.
Close the holes
- Fill holes with Fill Holes, or connect two holes with a tube with Stitch Two Holes.
- If a border is a seam where two patches touch, as on this teapot, weld it with Unite Close Vertices instead of filling it. Select Twin Edges shows such seams.
- For point clouds, use Select Boundary Points.
