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Add switchable rotation-frame correction (F R F^T default) to fix orientation/translation frame mismatch

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jessikitty
2026-08-04 09:56:43 +10:00
parent d10b5534a5
commit 3a961d64fd
1 changed files with 29 additions and 2 deletions
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public/js/ar/pose.js
+29 -2
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@@ -10,6 +10,32 @@ import * as THREE from 'three';
const _m = new THREE.Matrix4();
const _q = new THREE.Quaternion();
/* Rotation frame correction. The translation is converted from POS-IT's frame to
* the Three.js frame by F = diag(1,-1,-1) (the -t[1]/-t[2] negation). A rotation
* must be conjugated by the SAME F to stay in one consistent frame: R' = F R F^T.
* Applying F to translation but leaving rotation as-is (mode 'asis') puts position
* and orientation in different frames — position tracks but orientation tumbles
* (phone pitch leaks into world yaw/roll). Modes are runtime-switchable for on-device
* A/B: the debug overlay cycles ROT_MODES and calls setRotMode(). */
const F = new THREE.Matrix4().set(1,0,0,0, 0,-1,0,0, 0,0,-1,0, 0,0,0,1);
const Ft = F.clone().transpose();
export const ROT_MODES = ['frf', 'asis', 'fr', 'rf'];
let rotMode = 'frf'; // F R F^T — the frame-consistent default
export function setRotMode(m) { if (ROT_MODES.includes(m)) rotMode = m; }
export function getRotMode() { return rotMode; }
function correctRotation(R) {
// R is a Matrix4 holding the raw POS-IT rotation.
switch (rotMode) {
case 'asis': return R;
case 'fr': return _m2.multiplyMatrices(F, R);
case 'rf': return _m2.multiplyMatrices(R, F);
case 'frf':
default: return _m2.multiplyMatrices(F, R).multiply(Ft);
}
}
const _m2 = new THREE.Matrix4();
/* Input convention (matches the v1-validated fix): raw centered image coords are
* passed to POS-IT — NO Y pre-flip. The -t[1]/-t[2] negation below is what converts
* to the Three.js camera frame. Pre-flipping Y here double-flips the vertical axis
@@ -59,14 +85,15 @@ export class PoseEstimator {
}
candidate(rot, t, error) {
// Rotation as-is (row-major 3x3 -> Matrix4)
// Raw POS-IT rotation (row-major 3x3 -> Matrix4)
_m.set(
rot[0][0], rot[0][1], rot[0][2], 0,
rot[1][0], rot[1][1], rot[1][2], 0,
rot[2][0], rot[2][1], rot[2][2], 0,
0, 0, 0, 1
);
const quaternion = new THREE.Quaternion().setFromRotationMatrix(_m);
// Conjugate into the Three.js frame so rotation matches the flipped translation
const quaternion = new THREE.Quaternion().setFromRotationMatrix(correctRotation(_m));
// Translation: negate Y and Z only (confirmed fix)
const position = new THREE.Vector3(t[0], -t[1], -t[2]);
return { position, quaternion, error };