From a88895007611288964cc692e0753da3f72cae95d Mon Sep 17 00:00:00 2001
From: Shuo Zhong <shuo@strayos.com>
Date: Fri, 9 Jan 2026 18:14:52 -0600
Subject: [PATCH] bugfix: corret enu rotation matrix

---
 opensfm/exif.py | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/opensfm/exif.py b/opensfm/exif.py
index 2205007a8..6b0a67dc7 100644
--- a/opensfm/exif.py
+++ b/opensfm/exif.py
@@ -592,7 +592,13 @@ def extract_opk(self, geo: Dict[str, Any]) -> Optional[Dict[str, Any]]:
                 # Unit vector pointing north
                 xnp /= m
 
-                znp = np.array([0, 0, -1]).T
+                # Unit vector pointing up and perpendicular to north(xnp)
+                znp = p1
+                znp -= znp.dot(xnp) * xnp
+                m = np.linalg.norm(znp)
+                if m == 0:
+                    logger.debug("Cannot compute OPK angles, divider = 0")
+                    return
                 ynp = np.cross(znp, xnp)
 
                 cen = np.array([xnp, ynp, znp]).T