geossm.covmodel.buildMesh2d_new

geossm.covmodel.buildMesh2d_new(points, lowrank, domain=None, method='exact', max_edge=None, min_angle=21.0, seed=None)

Simplified front door to buildMesh2d_density’s density-matched mesh: picks a landmark-placement method instead of juggling snap_to_points/relax_iters directly, and leaves every other knob (min_edge, offset, cutoff, tol, max_iter) at buildMesh2d_density’s own defaults, which are self-tuning (derived from lowrank, the interest domain, and max_edge) and rarely need hand-adjustment. This wrapper adds no logic of its own – it exists to cut down the parameter surface, not to reimplement the mesher; call buildMesh2d_density directly for full control (a different cutoff/tol/max_iter, or a relax_iters count other than the “relaxed” method’s default of 2).

Parameters:

• points ((n, 2) array_like) – Observed locations.

• lowrank (float) – Value in [0, 1]. Target vertex count inside the interest domain, as a fraction of len(points); see buildMesh2d_density.

• domain (Polygon, MultiPolygon, or (possibly nested) list of these, optional) – The scientific-interest domain. Defaults to the convex hull of points.

• method ({"exact", "centroid", "relaxed"}, default "exact") –

  How landmark vertices relate to points (all are placed via k-means, so their density still tracks the density of points; this only changes where within that density each landmark actually sits):

  • "exact": landmarks coincide exactly with observed points (nearest-point snapping). Choose this when downstream model fitting needs the latent field’s degrees of freedom to sit directly on observations.

  • "centroid": landmarks are left at raw k-means centroids – close to the data, generally not exactly on it, no further smoothing.

  • "relaxed": k-means centroids, then a few rounds of Delaunay- neighbor smoothing. Usually the best triangle quality (interior angles), at the cost of landmarks no longer sitting at specific observations. Recommended over “centroid” whenever lowrank is close to 1: k-means with that many clusters places a centroid on every point regardless of method, so smoothing is what actually gives room to move landmarks off the raw data.

• max_edge (float, optional) – Largest triangle edge length outside the interest domain (and an upper bound on landmark spacing inside it). Defaults to 1/15 of the domain’s bounding-box diagonal.

• min_angle (float, default 21.0) – Soft target for the minimum interior angle (degrees); see buildMesh2d_density.

• seed (int, optional) – Seed for the landmark search, for reproducibility.

Returns:

• mesh (meshio.Mesh)

• convex_hull (shapely.geometry.Polygon) – The (buffered) convex hull the mesh was built over.

Examples

>>> mesh, convex_hull = buildMesh2d_new(points, lowrank=0.3)
>>> mesh, convex_hull = buildMesh2d_new(points, lowrank=1.0, method="relaxed")