Perhaps referring to a space within the interior of some larger structure, where the dimensions of the interior space are not obvious from the outside?
To say 'from the inside' in English you would be talking about something that was literally emerging from having been inside something (such as the guts emerging from the inside of his tauntaun, when Han Solo cut it open with his light sabre, so he and Luke could shelter overnight whilst trapped outdoors on the ice-planet of Hoth). To say 'on the inside' in English you would be describing what the interior of something was like (the classic example would be how Dr. Who's Tardis transport is much bigger on the inside than it looks like it will be before you go in).
If you are measuring something I think it is entirely appropriate to distinguish between a measurement taken inside something from a measurement taken outside. Imagine a pot with a thick base. The inner measurement could be shorter than the other one that measures the height of the pot including the thickness of the base.
yes, on another discussion the native speaker explained that "drinnen" was for a referenced space, whereas "innen" should refer to the location of an issue or thing
It is a masculine noun with 'er' ending, thus its plural doesn't change.
Ok but in the head of the German speaker, in this case, is plural like in English / Portuguese/etc?
Yes it is, they know is plural because of the "zwei" as if you used die Kinder, drei Keller, viele Zimmer, etc. I know it's strange, I'm a native spanish speaker and plurals are way easier like in english or portuguese, but you get used to it.
I wrote the same as it is something I would say as a native Australian speaker and it's still marked wrongly here
curious if one could translate this as: it is inside two meters high, meaning it is just under or within two meters in height. Anyone?
The literal translation into English english works. It is on the inside two metres up [the wall, for example]