Confirm tilts

public/exhibit.html

@@ -97,6 +97,6 @@
     }
   }
   </script>
-  <script type="module" src="js/exhibit.js?v=1"></script>
+  <script type="module" src="js/exhibit.js?v=2"></script>
 </body>
 </html>

public/orient-debug.html

@@ -146,13 +146,14 @@
       const pose = posit.pose(centredCorners(m, grab.width, grab.height));
       if (!pose) return null;
       const R = pose.bestRotation, t = pose.bestTranslation;
+      // NEW conversion (matches exhibit.js fix): rotation as-is, flip only
+      // translation Y and Z. Preserves correct orientation.
       poseMatrix.set(
         R[0][0], R[0][1], R[0][2],  t[0],
-        R[1][0], R[1][1], R[1][2], t[1],
-        R[2][0], R[2][1], R[2][2], t[2],
+        R[1][0], R[1][1], R[1][2], -t[1],
+        R[2][0], R[2][1], R[2][2], -t[2],
         0, 0, 0, 1
       );
-      poseMatrix.premultiply(flip); // F*M  (ar-head convention)
       anchor.matrix.copy(poseMatrix);
       anchor.matrixWorldNeedsUpdate = true;
 
@@ -258,7 +259,7 @@
     function buildLog() {
       const L = [];
       L.push('=== NEWBURY ORIENTATION LOG ===');
-      L.push('conversion: F*M (premultiply flip)  marker:' + MARKER_SIZE_MM + 'mm  cam:' + grab.width + 'x' + grab.height);
+      L.push('conversion: NEW (rotation as-is, flip translation Y/Z)  marker:' + MARKER_SIZE_MM + 'mm  cam:' + grab.width + 'x' + grab.height);
       L.push('cols: t,id,dist, RAW(pitch,roll,yaw), RENDER(pitch,roll,yaw), GYRO(beta,gamma,alpha)');
       L.push('gyro beta=front/back tilt, gamma=left/right tilt, alpha=compass');
       L.push('samples:' + log.length);