修正296970会崩溃的问题

libs/MVS/mask_face_occlusion.py

@@ -272,7 +272,8 @@ class ModelProcessor:
         valid_mask = vertices_cam[:, 2] > 1e-6
         vertices_valid = vertices_cam[valid_mask]
         if len(vertices_valid) == 0:
-            return np.zeros(len(vertices_cam), dtype=bool)
+            return (np.zeros(len(vertices_cam), dtype=bool), 
+                    np.zeros(len(vertices_cam), dtype=bool))
         
         visible = np.zeros(len(vertices_valid), dtype=bool)
         occlusion = np.zeros(len(vertices_valid), dtype=bool)