Make pose alignment optional without evo dependency

src/depth_anything_3/utils/pose_align.py

@@ -15,7 +15,11 @@
 from typing import List
 import numpy as np
 import torch
-from evo.core.trajectory import PosePath3D
+
+try:  # Optional dependency; HF Spaces may not have evo installed.
+    from evo.core.trajectory import PosePath3D
+except Exception:  # pragma: no cover
+    PosePath3D = None
 
 from depth_anything_3.utils.geometry import affine_inverse, affine_inverse_np
 
@@ -82,6 +86,26 @@ def _poses_from_ext(ext_ref, ext_est):
 
 
 def _umeyama_sim3_from_paths(pose_ref, pose_est):
+    if PosePath3D is None:
+        # Lightweight Umeyama Sim(3) without evo dependency
+        P = pose_ref[:, :3, 3]
+        Q = pose_est[:, :3, 3]
+        n = max(1, P.shape[0])
+        mu_P = P.mean(axis=0)
+        mu_Q = Q.mean(axis=0)
+        X = Q - mu_Q
+        Y = P - mu_P
+        cov = (X.T @ Y) / n
+        U, D, Vt = np.linalg.svd(cov)
+        S = np.eye(3)
+        if np.linalg.det(U @ Vt) < 0:
+            S[2, 2] = -1.0
+        R = U @ S @ Vt
+        var_Q = np.mean(np.sum(X * X, axis=1)) + 1e-8
+        s = float(np.trace(np.diag(D) @ S) / var_Q)
+        t = mu_P - s * (R @ mu_Q)
+        pose_est_aligned = _apply_sim3_to_poses(pose_est, R, t, s)
+        return R, t, s, pose_est_aligned
     path_ref = PosePath3D(poses_se3=pose_ref.copy())
     path_est = PosePath3D(poses_se3=pose_est.copy())
     r, t, s = path_est.align(path_ref, correct_scale=True)