Zipnerf point cloud and tsdf mesh export support (#3429)

Co-authored-by: J.Y. <[email protected]>

nerfstudio/scripts/exporter.py

@@ -73,8 +73,13 @@ def validate_pipeline(normal_method: str, normal_output_name: str, pipeline: Pip
         directions = torch.ones_like(origins)
         pixel_area = torch.ones_like(origins[..., :1])
         camera_indices = torch.zeros_like(origins[..., :1])
+        metadata = {"directions_norm": torch.linalg.vector_norm(directions, dim=-1, keepdim=True)}
         ray_bundle = RayBundle(
-            origins=origins, directions=directions, pixel_area=pixel_area, camera_indices=camera_indices
+            origins=origins,
+            directions=directions,
+            pixel_area=pixel_area,
+            camera_indices=camera_indices,
+            metadata=metadata,
         )
         outputs = pipeline.model(ray_bundle)
         if normal_output_name not in outputs: