visualizing obstacles in rviz (Gridcells vs map element)

edit

hello,

I am trying to show obstacles / objects in rviz. i'm using costmap_2d for that

in the video of Using rviz with the Navigation Stack tutorial obstacles can be shown by using GridCells element in rivz (nav_msgs/GridCells).

But in the costmap_2d page and in the published topics there is only /grid (nav_msgs/OccupancyGrid). so i should use map element in rviz to see obstacles (/costmap topic)

since both of them are related obstacles why the both pages implicate different things? And how can i publish /obstacles topic to choose GRIDCELL display just like the video???

i tried to do plugins but again there's only /costmap topic for me to use.