What ghost ranges does a single-ray lidar twin never produce at a depth edge?
research/flyingpixel-twin
Single-ray lidar twin vs a finite beam with merged pulses at a depth edge: ghost-range band exactly 2Φ⁻¹(1−ε/D) beam widths (2.56 at ε/D=0.1, none at ε≥D/2), shifts and narrows for unequal brightness, matches a scan simulation to 0.3%, and a 3-of-5 persistence filter still passes 80–99% of ghosts.
What it found
A one-ray twin returns the near or the far surface at a depth edge; a real beam with a Gaussian footprint and merged return pulses reports an energy-weighted range in free space. The ghost band is exactly 2Φ−1(1−ε/D) beam standard deviations wide for equal energies (2.56 at ε/D = 0.1, 4.65 at 0.01, none once ε ≥ D/2), checked against a direct scan to 10−4, and shifts toward the near side and narrows when the far wall is brighter (1.67 at a 100× energy ratio). A scan with an edge every ≈ 100 beams has a ghost fraction equal to the prediction to within 0.3%, and a 3-of-5 persistence filter on a static robot passes 80–99% of ghosts because they come from geometry, not noise. Stylised: hard merge threshold, 1-D footprint, centroid detector, no real scans.
A figure from its own output
Paper, code and results
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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.