interpolating depth values

[Lutz Vieweg]

On 09/25/2017 01:36 AM, Linus Torvalds wrote:
> Since when is a depth of "-0.2m" interesting data? It's shit.

Actually, water depths like "-0.2m" are physically quite possible -
though I agree that divers are not very likely to experience them.

Imagine a cavern in an area where there is a tidal range.

ASCII-Art of Situation at time A:

Air
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...
################################...
Ocean###########################...
################________________...
###############/   Land Mass    ...
############# /   ______________...
#############/   /#####D########...
############/   /###############...
###########/   /################...
###########|__/#################...
################################...
################################...


At time B:

                 ________________...
                /   Land Mass    ...
Air           /   ______________...
              /   /#####D########...
^^^^^^^^^^^^/   /###############...
###########/   /################...
Ocean######|__/#################...
################################...


If the "land mass" atop the cavern is almost air-tight, water cannot
escape it as quickly as low tide comes, so for quite a whilte there
will be an area of water with "negative water depth" - the "D" below
the Land Mass depicts the location where a diver can easily get to,
and in situation "B" his dive computer should indicate a negative depth.

And: A diver actually has a significant risk of getting DCS when
diving in such an area.

Regards,

Lutz Vieweg