feat(local_visualizer.py): add check dir exist (#1828)

* feat(local_visualizer.py): add check dir exist

* fix(local_visualizer.py): use mmengine API

* format(local_visualizer.py): remove useless

* style(local_visualizer.py): format

mmdet3d/visualization/local_visualizer.py

@@ -5,6 +5,7 @@
 
 import mmcv
 import numpy as np
+from mmengine import mkdir_or_exist
 from mmengine.dist import master_only
 from torch import Tensor
 
@@ -605,6 +606,8 @@ def add_datasample(self,
                 win_name=name,
                 wait_time=wait_time)
 
+        mkdir_or_exist(out_file)
+
         if out_file is not None:
             if drawn_img_3d is not None:
                 mmcv.imwrite(drawn_img_3d[..., ::-1], out_file + '.jpg')