Does a well-featured twin overstate scan-matching accuracy in a corridor, where the scan cannot see the along-track direction?

research/corridor-twin

Scan matching in a corridor: along-track information is exactly zero without door frames, 1.6–6× a room's along-track sd with them; a filter fed the room twin's covariance has NEES 432–1535 over a blind span, and the exact covariance holds only inside a ~0.2 m basin. Stylised.

8 tests

What it found

In a bare corridor the point-to-line information matrix is exactly singular along the track and the matcher returns its initial guess; door-frame stubs every 20/10/5/2 m give an exact along-track sd of 8.1/6.3/3.9/2.2 mm (MC 7.3/6.2/4.3/2.4), 1.6–6× a well-featured room's 1.35 mm, while lateral accuracy (≈ 0.8 mm) is unchanged. A Kalman filter fed the room twin's 1.9 mm covariance across a 20 m blind span has NEES 432 (1 cm/step odometry) and 1535 (2 cm/step) against 0.75 for the exact-covariance filter; the exact covariance is valid only inside a matcher basin of ≈ 0.2 m, and the covariance-aware filter is still overconfident at re-entry (NEES 2–8). Stylised: simulated 2D lidar, one-dimensional filter.

A figure from its own output

Figure produced by research/corridor-twin: sd_x — corridor-twin/experiments/sd_x.svg, written by the project's own experiment code.

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.