layout op• Data kinds: none → signal (an op determined by its arguments alone — it takes no image or data input)
• Call: import fullseye as fs; fs.ledger.projection_angles(n_angles=180, span_deg=180.0, scheme='uniform', start_deg=0.0) (to call the implementation directly, import tomography; tomography.projection_angles(n_angles=180, span_deg=180.0, scheme='uniform', start_deg=0.0); from the registry, opstomography.get("projection_angles"))
The angle sequence of a scan, in degrees, as a 1-D float64 array.
Three schemes, and the difference between them is what happens when a scan is cut short:
• "uniform" — start + span * k / n. The textbook scan. A prefix of it covers only a wedge, so an interrupted uniform scan is a limited-angle scan.
• "golden" — increments of 180/phi = 111.246... degrees, wrapped into [start, start+span). Every prefix is near-uniform, so an interrupted golden scan is a *sparse* scan, which is a far easier problem. Largest angular gap left by a scan that stops early, measured:
scheme after 32 of 180 all 180
uniform 149.000 deg 1.000 deg
golden 10.031 deg 1.464 deg
bit-reversed 8.000 deg 1.000 deg
Uniform's 149-degree hole is the entire limited-angle problem arriving by
accident. Bit-reversed is the only one of the three that is good at both
ends; golden's price for working at *every* prefix length rather than only
at powers of two is a completed set 1.46x less even than the grid.
• "bit-reversed" — the uniform grid, visited in bit-reversed order. Same guarantee as golden for power-of-two prefixes and exactly uniform at the end, which golden is not.
*span_deg* is the total angular range. 180 degrees is the complete data set for parallel beam — projections at theta and theta+180 are mirror images and carry no new information — so a 360-degree span is redundancy, not resolution, and anything under 180 is the limited-angle problem.
:param n_angles: number of views, 1 .. 65536. :param span_deg: total angular range in degrees, > 0. :param scheme: one of ANGLE_SCHEMES. :param start_deg: angle of the first view. :returns: (n_angles,) float64 array of degrees. :raises ValueError: on a non-int count, a non-positive span, a non-finite
start, or an unknown scheme.
• 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.
• The canonical algorithm (author, year) and its uses are named in the family usage guide above.
• ct_reconstruction — py -3.11 examples/ct_reconstruction.py
• poc_battery_ct_degradation — py -3.11 examples/poc_battery_ct_degradation.py
• poc_ct_fidelity — py -3.11 examples/poc_ct_fidelity.py
• tomography_reconstruct — py -3.11 examples/tomography_reconstruct.py
signal as input)—
layout)*Provenance: tomography.py — TOMOGRAPHY 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.