Efficient way to update an existing grid map object

[hsurya08]

Hi,
Thank you for the amazing work. I am working on the navigation of quadruped robot and as a part of the project I was using the elevation_mapping package that utilizes grid_map as one of the dependencies. As a part of this project I have created an additional node that subscribes to the "elevation_mapping_raw" topic which is in "grid_map_msgs::GridMap" message and converts it "grid_map::GridMap" message and stores in a new variable called "terrainDataHolder". I want to update this terrainDataHolder variable every time there is new data being published on the elevation_mapping_raw topic in a efficient way rather than just replacing the entire map data. It would be very helpful if you can guide me on this or provide any suggestions on the best possible method to implement this. Thanks in advance!