Wrong profiles importing from Diving log 5.0 to Subsurface 4.1

Linus Torvalds torvalds at linux-foundation.org
Tue Jul 22 10:16:54 PDT 2014


On Tue, Jul 22, 2014 at 9:08 AM, Davide DB <dbdavide at gmail.com> wrote:
> Good catch indeed!
> So UDDF has the same problem with depths.

It may not be a "problem".

Many (most?) dive computers have the notion of a per-dive maximum
depth totally *separately* from the actual sample depths. The maximum
depth may be measured at a finer interval than the samples, for
example, and/or might be done without any smoothing of the instant
data etc.

Normally such a max depth should be at least as deep as the sample
depths, but who knows.

Anyway, the dive logging software may or may not support a separate
max depth, and may or may not correct that max depth depending on
samples. For example, in subsurface, we *do* take the max depth from
the dive computer, but then we also end up saying "hey, if any samples
have a deeper depth, we'll correct the max depth" (see
fixup_dive_dc()).

So it's entirely possible that the maximum depth is off from the
maximum sample depth by a few feet. Looking at your divinglog
question, it sounds like divinglog doesn't do the "max depth fixup"
that we do. But not doing the fixup isn't exactly wrong, it's just a
"what is the meaning of max depth? Do you want to save what the
computer reported even if it doesn't make a whole lot of sense or
not?"

            Linus


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