AR: sub-pixel corner refinement, ROI-first detection, anchor coplanarity check

public/js/ar/detect.js

@@ -13,8 +13,21 @@ export function createDetector() {
  * rawIds tells you what the camera actually saw.
  */
 export function detectMarkers(detector, imageData, knownIds) {
-  const raw = detector.detect(imageData).filter(m => quadArea(m.corners) > 100);
+  return finaliseMarkers(detectRaw(detector, imageData), knownIds);
+}
 
+/* Raw decode over whatever image you hand it — a full detection frame or an ROI
+ * crop. Split out from detectMarkers so roi.js can run the same decode on a crop
+ * and have the results finalised together with everything else. The area floor
+ * is in the pixels of THIS image, which is what we want: a crop is higher
+ * resolution, so a marker that scrapes past the floor in a full frame clears it
+ * comfortably in a crop. */
+export function detectRaw(detector, imageData) {
+  return detector.detect(imageData).filter(m => quadArea(m.corners) > 100);
+}
+
+/* Dedupe, filter to the scene, attach diagnostics. */
+export function finaliseMarkers(raw, knownIds) {
   /* Deduplicate by id. Two quads in one frame can decode to the same id — a
    * misread of a different crest under blur or glare. That is poison for the
    * board solve: both quads are handed the SAME world corners, so solvePnP gets
@@ -36,6 +49,14 @@ export function detectMarkers(detector, imageData, knownIds) {
   return usable;
 }
 
+/* Centre of a quad — used to merge markers that the same crest produced in two
+ * overlapping ROI crops. */
+export function quadCentre(c) {
+  let x = 0, y = 0;
+  for (let i = 0; i < 4; i++) { x += c[i].x; y += c[i].y; }
+  return { x: x / 4, y: y / 4 };
+}
+
 export function quadArea(c) {
   // shoelace
   let a = 0;