transform op• Data kinds: voxel → sdf
• Call: import fullseye as fs; fs.ledger.signed_distance_field(vol, device='cpu', iso=0.5) (to call the implementation directly, import match3d; match3d.signed_distance_field(vol, device='cpu', iso=0.5); from the registry, ops3d.get("signed_distance_field"))
• GPU: this op has a GPU path (device="cuda")
Occupancy/density voxels → a signed distance field SDF (inside < 0, outside > 0). edt_jfa applied to both sides.
The SDF is an excellent representation for matching (smooth, gradient = normal, 0 isosurface = surface). It is built from the difference of the inside/outside Euclidean distances. GPU native. Converts back and forth voxel↔SDF↔occupancy.
Definition: with occ = vol > iso, d_out = edt_jfa(occ) (distance from each voxel to the nearest occupied voxel, 0 inside the occupied region), d_in = edt_jfa(~occ) (to the nearest unoccupied voxel), and sdf = d_out − d_in. Outside is +distance, inside is −distance (in voxel units, Euclidean). Since the distances are between voxel centres, no voxel becomes 0: occupied voxels on the boundary are −1, adjacent unoccupied voxels are +1 (the 0 isosurface lies between voxels). iso is the density → occupancy threshold (default 0.5; for count density this means "1 point or more"). For an all-occupied or all-empty volume, the distance on the side without seeds saturates at 1e6: all-occupied gives −1e6, all-empty gives +1e6 (no exception). Returns (D,H,W) float32 numpy.
Downstream: back with sdf_to_occupancy, surface with voxel_to_mesh(sdf, iso=0.0), normal field with sobel3d.
• 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.
• transforms_repr — py -3.11 examples_3d/transforms_repr.py
sdf as input)sdf_to_occupancy · fuse_to_voxel · integrate · extract_surface_points · query_distance · sdf_union · sdf_intersect · sdf_subtract
transform)points_to_voxel · gaussians_to_voxel · mesh_to_voxel · mesh_to_points · depth_to_points · voxel_to_mips · voxel_to_mesh · tsdf_from_depth
*Provenance: match3d.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.