Defeaturing and simplification

Short segments turned back into lines, an arc and a spline A shape optimization result, fitted with splines

Imported and computed geometry often contains details that a mesher cannot use: ends that miss each other by a hair, edges far shorter than the part, straight runs in many pieces, and arcs or free-form curves tessellated into short segments. Simplify cleans these up in place, Simplified returns a cleaned copy, and the exports to OpenCASCADE and netgen run the same steps. Gaps, small edges and collinear pieces are handled below 10⁻⁷ by default, the resolution of OpenCASCADE and netgen. Fitting arcs and splines is switched on when needed, and every fit is checked against the edges it replaces and rejected if it strays further than its tolerance.

In this section

Small gapsEnds that miss each other, joined within a tolerance.

Small edgesEdges shorter than a tolerance, removed with their ends merged.

Collinear linesStraight runs in several pieces, joined into one line.

Fitting arcsA measured bore turned back into three arcs, with the tolerance and the checks.

Fitting splinesA tessellated ellipse turned back into two B-splines.

The steps, in order

Step	Option	Default
Close small gaps	close_gaps_smaller	1e-7
Merge collinear lines	merge_collinear_closer	1e-7
Fit arcs	fit_arcs: True, or a dict of tol, max_edge_length, max_edge_angle, ignore_edges_smaller	Off
Fit splines	fit_splines: True, or a dict of the same options	Off
Remove small edges	remove_edges_smaller	1e-7
Remove free edges (touching no other edge at either end)	remove_free_edges	On for faces, off for wires
Remove small faces	remove_faces_smaller, merge_small_faces_instead	0 (none)

The defaults are stored in px.config and can be changed for the whole session. A dict for a fit changes the options it names and switches the fit on:

import planex as px

px.config.fit_arcs = dict(tol=1e-4)
print(px.config.fit_arcs)

{'enabled': True, 'tol': 0.0001, 'max_edge_length': 0.0001, 'max_edge_angle': 30.0, 'ignore_edges_smaller': 1e-05}