symmetry op• Data kinds: points → measurement
• Call: import fullseye as fs; fs.ledger.reflection_symmetry_score(points, plane_point, plane_normal) (to call the implementation directly, import symmetry3d; symmetry3d.reflection_symmetry_score(points, plane_point, plane_normal); from the registry, ops3d.get("reflection_symmetry_score"))
Reflection-symmetry score = chamfer(mirrored, original) / the median nearest-neighbour spacing (smaller is more symmetric; scale invariant). → float.
Reflects the point cloud in the plane with reflect_points and divides the symmetric Chamfer distance to the original point cloud (chamfer_distance:
the mean of the means of the nearest-neighbour distances in both directions) by the median nearest-neighbour spacing of the original point cloud. It is the dimensionless quantity "how many point spacings the mirror image is off from the original points", so scaling the coordinates by a constant does not change the value.
• points: (N,3) point cloud. plane_point / plane_normal: candidate plane (the normal is normalised internally).
• fail-closed: the point cloud is empty or not (N,3) (chamfer_distance raises ValueError), or all points coincide so that the spacing is undefined (ValueError). Only when duplicate points make the median spacing 0 is the RMS radius about the centroid × 1e-12 used as a floor.
Caution when reading: even for an exactly symmetric shape, the mirrored points do not land exactly on the original sample points, so the score is not 0 and its floor is about the point spacing (for measured values see the table of detect_reflection_symmetry). Rather than deciding acceptance by a threshold, sweep several candidates and look at the minimum and its difference from 2nd place (margin). To try candidate planes other than the 3 PCA axes, sweep this function directly over the plane parameters.
• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).
• Operator provenance and references — the sources of the research/methods this op family came from.
• dl_mesh_symmetry — py -3.11 examples_3d/dl_mesh_symmetry.py
• reflection_symmetry — py -3.11 examples_3d/reflection_symmetry.py
measurement as input)vol_gaussian_psf · fuse_to_voxel · fresnel_reflectance · snell_angle
symmetry)detect_reflection_symmetry · detect_rotational_symmetry · reflect_points
*Provenance: symmetry3d.py — 3D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.