Hi Red,
The default settings are tuned for room-size or small appartment scanning.
For larger scanning, it is possible to reduce resolution the real-time rendering to save RAM, or even completly save on drive (without any feedback in data recorder mode).
If you are struggling to export the optimized mesh (lack of RAM), it is possible to use the standalone app to do so.
See these related posts:
http://official-rtab-map-forum.206.s1.nabble.com/iOS-best-practices-for-only-tracking-long-recordings-td10300.htmlhttps://github.com/introlab/rtabmap/issues/1467#issuecomment-2727054208http://official-rtab-map-forum.206.s1.nabble.com/Best-Export-Settings-For-OBJ-td10108.htmlhttps://github.com/introlab/rtabmap/wiki/Multi-Session-Mapping-with-RTAB-Map-Tango#7-export-the-meshTo keep your phone working, iOS would limit the maximum RAM than an App can use, which could explain why no more than 6GB is available on your phone for this app.
Cheers,
Mathieu