Design Nomenclature / Form & Geometry
Reflection
Also called mirror, glide reflection, mirror symmetry, bilateral symmetry
- Form & Geometry
- Composition
- 2D & 3D
The isometry mapping each point to its mirror image across a plane, or across a line in 2D. It reverses handedness and winding order, so a mirrored mesh renders inside-out until its normals are recomputed. Composed with a translation along the mirror line it gives a glide reflection — the footprint pattern, and the only planar isometry with no fixed point and no reversal you can undo by turning.
In practice
'Mirror' is the tool. A symmetry modifier reflects across the object's local plane, not the world's, so moving the pivot silently moves the mirror — the commonest cause of a model that will not weld down the middle.