# Multi-session mapping with ROVIOLI¶

## Creating a multisession map¶

ROVIOLI can be used as a frontend to create multisession maps, i.e. maps constructed using multiple single recordings (often called missions within the maplab framework). Creating such maps is very simple and consists of two steps:

1. Build separate maps using ROVIOLI and store them as VI-maps: Running ROVIOLI in VIO mode

2. Merge the maps and jointly refine them using the offline maplab console: Preparing a multisession map

## Localizing against a multisession map¶

You can create a localization map out of a VI-map using the following command within the maplab console:

generate_summary_map_and_save_to_disk --summary_map_save_path your_summary_map


The map saved in your_summary_map can then be used by ROVIOLI to localize, as described in ROVIOLI Localization Mode tutorial.

## Extending a multisession map¶

If you would like to include the new mission in your multisession map, you should load both the multisession map and the new map and just follow the Multisession mapping tutorial.