Chord tolerance is a per-part decision

B-rep to triangles is the first lossy step in any CAD-to-web pipeline, and the setting that controls it is usually a single global number chosen by whoever ran the export.

That number cannot be right. A visible chrome bezel needs 0.05 mm chord tolerance or it reads as faceted. A bracket hidden inside an enclosure is fine at 0.8 mm and will never be seen. Use the bezel number globally and the assembly is 40 MB; use the bracket number and the product looks cheap.

So we compute visibility first — an ambient-occlusion-style sampling pass that scores how much of each part is ever visible from the configured camera envelope — and assign tolerance from the score. Fully occluded parts often drop out entirely.

On a typical machine assembly this is the difference between a 6.2 MB and a 1.1 MB payload, with no perceptible visual change. It is also entirely automatable, which matters when a PLM release drops 4,000 parts on you.

One caveat: visibility is configuration-dependent. Open a door in the configurator and previously hidden parts become visible. The visibility pass has to run across the configuration envelope, not the default state.