solvecraft/tests/ssi-corpus

SSI corpus

119 surface/surface intersection (SSI) cases with exact ground truth, from ssi-corpus (cases/data, commit b04c8a6), dual-licensed MIT OR Apache-2.0 (LICENSE-MIT, LICENSE-APACHE here). Each case is stored gzip-compressed as cases/<id>.json.gz (the raw JSON is 31 MB; compressed, 9 MB). The content is unchanged.

The 25 y23_* cases come from Yang, Jia and Yan, "Topology Guaranteed B-Spline Surface/Surface Intersection", ACM Transactions on Graphics 42(6), Article 211, 2023 (CC BY 4.0): six use the paper's published surfaces, nineteen are reconstructions of its figures with closed-form truth. Each cites the paper in its source field.

A case

• surfaces: the two surfaces (plane, cylinder, cone, sphere, torus as typed parameters; B-spline and NURBS as control nets with knots and weights, optional domain trim box).
• truth: one exact description per surface, used for distances: implicit plane, sphere, cylinder, cone, torus, ellipsoid, quadric, polynomial heightfield, or param (a rational polynomial patch, distance by closest point).
• expected: the true intersection, sampled densely: branches (polylines), isolated_points, singular_points and coincident_regions (boundary polylines).
• cov_tol: the coverage tolerance; optional ill_cond (conditioning factor) and feature_size.

How the tests use it

crates/smlib/tests/ssi_score/ is a Rust port of the corpus scorer (scoring/score.py and the distance helpers of scoring/ssi_geom.py). It takes a case and an engine result (sampled curves with xyz, uv1, uv2, both surfaces evaluated at the UV samples, the curve type; isolated points; the status; or a crash) and returns the verdict. crates/smlib/tests/ssi_corpus.rs checks the scorer on every case, and, as an ignored test, its parity with the Python scorer on the raw runner outputs (see that file).

Scoring rules

With an approximation tolerance tol, acc_tol = 10 * tol. The coverage tolerance is cov_tol, widened for ill-conditioned cases to max(cov_tol, min(0.5, 2 * acc_tol * ill_cond)). Runs at the engine's default tolerance have no acc_tol and judge coverage and joins with a floor of 5e-3 (cases with a feature_size under it are N/A). Output curves of type TOUCHING, or no larger than cov_tol, count as points. Verdicts, most severe first (all flags are kept):

• CRASH: the engine died or exceeded the time limit.
• ERROR: a non-success status, unless nothing was expected and nothing was returned.
• INCOMPLETE: an expected branch, isolated point or coincident region boundary is not covered within the coverage tolerance.
• WRONG TOPOLOGY: output off the true intersection; a different set of connected components (curves with their free-end count, and points, joined within cov_tol); two output curves that overlap by more than 20%; a singular point that no curve end or point lies on; non-finite samples.
• INACCURATE: a 3D sample farther than acc_tol from either surface, or a surface evaluated at the output UV farther than acc_tol from the other surface.
• PASS.