We have been experimenting with using the iphone's 3d sensors (it uses a combination of structured light and lidar for it's 3d sensing) in the lava tubes in Iceland and have found it to be vastly superior to using the disto alone. This is partially due to how strongly magnetic the lava is (magnetic anomalies of 10s of degrees are very common). In addition to the lidar and the structured light sensors, the iPhone uses its magnetic sensors and accelerometers, this helps it create an accurate model but does also cause some issues. While the addition of the accelerometers and 3d sensors do really help, the magnetic anomalies do still sometimes cause us some issues, the models tend to tear and become inaccurate when we encounter those. In tight passages it is also very easy to bump the phone against the floor or ceiling and due to the accelerometers this always messes up the map. To mediate this, we try to keep our scans to no more than 20 minutes at a time when surveying in difficult sections and stitch them together afterwards. This prevents us from having to repeat large and difficult scans, but does add some extra work at the computer.
In addition to giving a much more detailed model of the cave than one would get with the disto the survey also goes much faster. We have easily halved the survey time in addition to removing much of the frustrations of the previous methods using the disto x (although it does introduce some new frustrations of its own).
We have not experimented with creating maps in Therion from iphone generated 3d models. None of us has prior experience with working with 3d models so that alone has been a quite steep learning curve with still some way to go, and on top of that we have only limited experience using Therion, so that is another learning curve we have to scale. I have experimented with using Jari Arkko's cave-outliner (
https://github.com/jariarkko/cave-outliner) to generate outlines and cross-sections and used Inkscape to add details.
This year's expedition was recorded and included in a documentary celebrating the islands 60 year anniversary. It is available online here (only available in Icelandic, sadly):
https://www.ruv.is/sjonvarp/spila/surtsey/35251/ag5o1h - The cave section starts at 49:30 and the iPhone lidar can be seen in action at about 52:50
Best regards,
Þórir Már