# Talk:Proposed features/natural=cave

## Multipolygon relation?

Why are you defining a new relation type (<type=cave>)? Wouldn't it be possible to re-use the multipolygon relation (<type=multipolygon> + <natural=cave>)? --Biff (talk) 18:50, 16 June 2016 (UTC)

I think it needs several different types of "members" for the relation: outlines of cave sections like domes, ways for tunnel like linear sections of the cave, hiking ways and other objects inside the cave and while at it I think I should also add cave entrances to the relation. I am wondering if I should add some more special roles like "dome" as synonym for outline?
It might also turn out that people will use multipolygons for particularly complicated outlines of cave sections like a dome with several pillars which I think would be fine. RicoZ (talk) 11:31, 17 June 2016 (UTC)

## How to map "open roof" domes?

Stumbled upon the Callao cave system where some caves have open "roof"s: https://www.google.de/search?q=Callao+cave+system

The fully open parts could be mapped as natural=sinkhole RicoZ (talk) 17:11, 17 June 2016 (UTC)

## Caves are three-dimensional. How can we map pits/pots?

Inside caves often there are vertical shafts that need special equipment, I think they should be mapped. Reference --Alejandroscf (talk) 00:21, 23 June 2016 (UTC)

That part is still in the making, I see two possibilities:
• 3D mapping of cave shape and volumes
• mapping of features like pits, domes, cliffs as part of the mostly 2D natural=cave concept. Eg natural=cliff+location=cave could be a cliff in a cave
The cliff and other features inside caves are already part of the proposal. For the 3D mapping I am looking for inspiration in various other proposals (Simple Indoor Tagging, Bridge3D) and haven't decided which way to go yet.
One problem of the current 2D proposal which I am looking for a good solution is how to map he situation of a high dome where some ways enter the dome at different "levels". Seems all the ways should share nodes with the natural=cave outline of the dome and have different level=*.. seems to work with lifts so it might work here as well?
RicoZ (talk) 10:46, 26 June 2016 (UTC)
2D aproach sounds great, in multi level domes in order to "sort" the entrances, instead of levels, may be height=*, min_height=* and width=* (that's the same approach as widows in 3D buildings) could be added to the dome-tunnel intersection node in order to to determine its dimensions and height from the floor of the dome (or may be could be better to use insteada new tag (deepness=*?) with its deepness from the cave entrance, that new tag could be used in any node to determine its z-position) --Alejandroscf (talk) 23:19, 29 June 2016 (UTC)
Ok, for the 2D approach feel free to suggest a set of tags like natural=pit etc and complain where the wording of the proposal should be improved.
Also like the analogy with the windows in 3D buildings (which wiki page is that?). Unlike windows some cave tunnels may also be areas so sometimes they won't fit as node. RicoZ (talk) 11:33, 1 July 2016 (UTC)