69 lines
2.8 KiB
JavaScript
69 lines
2.8 KiB
JavaScript
/* detect.js — tuned ArUco 4x4 detection.
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* Phantom-ID fix: reject any marker decoded with hamming distance > 0 (maxHamming: 0).
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*/
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export function createDetector() {
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return new AR.Detector({ dictionaryName: 'ARUCO_4X4_1000', maxHammingDistance: 0 });
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}
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/* Returns the markers usable for solving: present in the scene, sane geometry.
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* The returned array also carries diagnostics so the HUD can distinguish
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* "nothing detected" from "detected but not in the scene" — the latter looks
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* identical on screen but means the scene never loaded, or the crest belongs to
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* a different layout. knownIds may be null/empty; then nothing is solvable and
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* rawIds tells you what the camera actually saw.
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*/
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export function detectMarkers(detector, imageData, knownIds) {
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return finaliseMarkers(detectRaw(detector, imageData), knownIds);
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}
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/* Raw decode over whatever image you hand it — a full detection frame or an ROI
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* crop. Split out from detectMarkers so roi.js can run the same decode on a crop
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* and have the results finalised together with everything else. The area floor
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* is in the pixels of THIS image, which is what we want: a crop is higher
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* resolution, so a marker that scrapes past the floor in a full frame clears it
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* comfortably in a crop. */
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export function detectRaw(detector, imageData) {
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return detector.detect(imageData).filter(m => quadArea(m.corners) > 100);
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}
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/* Dedupe, filter to the scene, attach diagnostics. */
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export function finaliseMarkers(raw, knownIds) {
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/* Deduplicate by id. Two quads in one frame can decode to the same id — a
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* misread of a different crest under blur or glare. That is poison for the
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* board solve: both quads are handed the SAME world corners, so solvePnP gets
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* two contradictory constraints for one point set and the pose collapses
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* (seen on device as reproj jumping to 5px+). Keep the largest quad, which is
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* the closest and best-resolved reading. */
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const best = new Map();
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for (const m of raw) {
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const area = quadArea(m.corners);
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const prev = best.get(m.id);
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if (!prev || area > prev.area) best.set(m.id, { m, area });
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}
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const uniq = [...best.values()].map(e => e.m);
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const usable = (knownIds && knownIds.size) ? uniq.filter(m => knownIds.has(m.id)) : [];
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usable.rawCount = raw.length;
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usable.rawIds = raw.map(m => m.id);
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usable.dupes = raw.length - uniq.length;
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return usable;
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}
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/* Centre of a quad — used to merge markers that the same crest produced in two
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* overlapping ROI crops. */
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export function quadCentre(c) {
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let x = 0, y = 0;
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for (let i = 0; i < 4; i++) { x += c[i].x; y += c[i].y; }
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return { x: x / 4, y: y / 4 };
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}
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export function quadArea(c) {
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// shoelace
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let a = 0;
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for (let i = 0; i < 4; i++) {
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const p = c[i], q = c[(i + 1) % 4];
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a += p.x * q.y - q.x * p.y;
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}
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return Math.abs(a) / 2;
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}
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