use gsplat strategy interface to simplify splatfacto (#3376)

* use gsplat strategy interface to simplify splatfacto

* change splatfacto-big densify_grad_thresh to 0.0005

* upgrade gsplat version

* filter low opacities when exporting

* remove num_sh_bases

---------

Co-authored-by: Jianbo Ye <jianboye@amazon.com>
Co-authored-by: Justin Kerr <justin.g.kerr@gmail.com>

Author: 3 people

nerfstudio/configs/method_configs.py

@@ -663,8 +663,7 @@
         ),
         model=SplatfactoModelConfig(
             cull_alpha_thresh=0.005,
-            continue_cull_post_densification=False,
-            densify_grad_thresh=0.0006,
+            densify_grad_thresh=0.0005,
         ),
     ),
     optimizers={