Unbounded scene config

[Learningm]

I see the coarse_train config setting is N_iters = 0 in nerf_unbounded_default.py.
https://github.com/sunset1995/DirectVoxGO/blob/main/configs/nerf_unbounded/nerf_unbounded_default.py#L16
What's the purpose of this setting? It seems we skip the coarse stage.

Another question, how to inspect the fine model training result similar like --export_coarse_only flag?
It seems if we skip the coarse stage, we don't have model to inspect before the fine stage.
Thanks.