How accurate must a scan be to rebuild a part as parametric CAD?
research/sensing-scan2cad
How accurate must a scan be to rebuild a part as parametric CAD? On synthetic plate scans, RANSAC plane and circle fits give all five dimensions within 0.2 mm for noise up to 0.2 mm, but at 0.5 mm noise the error is a bias (thickness −0.20 mm) that more points do not remove, and a 0.5% scale error alone moves an 80 mm length by 0.40 mm. Synthetic, one shape.
What it found
Synthetic point-cloud scans of an 80×40×10 mm plate with two 8 mm holes, fitted by RANSAC planes and circle fits. With scan noise of 0.2 mm or less every scan gives all five dimensions within 0.2 mm at 2 000 points or more (worst RMS 0.09 mm). At 0.5 mm noise only 0–50% of scans are usable at any point count because the error is a bias: thickness reads 0.20 mm low and the bias grows with the inlier band (−0.07 to −0.38 mm for 1.5σ to 4σ). A scale error of 0.5% from a reconstruction with no scale reference already moves an 80 mm length by 0.40 mm. Stylised: one shape, assumed Gaussian noise, pre-registered scan, generated CadQuery script not run.
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.