Could you include in the package an option for in which the inpaint filter only works in regions with NaN values within the range of the sensor? Currently, the inpaint filter adds a value everywhere there is a NaN value (not a point from the pointcloud). That means that behind a wall there is a value there and upon using costmap conversion, it is marked as explored.

In my case, using a 3D Lidar pointcloud I have customly modified it to fill only the NaN regions in which its bounding box is not touching the boundaries of the grid_map. It is not the best of the works but I would like to have something official to rely on.