Interactive Extended Elevations

[Andy Waddington on Survey stuff]

>> list *all* those legs which are to be *included*

Olly> If you update the survey you're likely to want the new legs to
      appear in the extended elevation by default. ... there are likely
      to be far fewer legs excluded than included ...

I strongly disagree. If you are doing something like an EE of a route
through a complex cave, it is likely that only a small subset of the legs
would be needed. If I update the survex data by adding a survey nowhere near
this route, I don't want to have to go to my EE-descriptor and say "exclude
these (new) legs which you didn't know about before, and don't need to know
about now."

If the new bit of survey happens to relate in some way to the particular bit
of cave that I'm showing on my EE, then I probably want to review the
descriptor and decide whether to include some or all of the new survey and
perhaps miss out some of the existing survey.

If on the other hand, you are doing an EE of the whole of a small cave, then
adding a new survey will probably still require you to review the EE to
avoid crossing legs and other confusion, so there is no great trade off
between listing excluded against included legs.

If you list legs to be included, then the existing descriptor will always
continue to show what you originally intended when new survey is added. If
you list legs to be excluded, you will always get stuff you hadn't
considered when new survey is added.

Adding new survey is a whole lot more common than deleting a chunk of survey
with nothing to replace it...

> most people would use the graphical editor anyway

So for most people, there is no visible difference between the descriptor
listing included as against excluded legs. But if you list excluded legs you
will *always* need to use the graphical editor to get what you had before
when new survey is added. The new survey may not even connect to what you
had before (if it hangs off an excluded part), which will tend to complicate
things.

One point that I omitted to make in my previous post is that for a dataset
like Kaninchenhohle (or OFD, or Easegill ...) there is usually going to be
a single "definitive" dataset for the survey data. We try, anyway. But there
are often lots of users of that dataset, perhaps each wishing to prepare an
extended elevation to illustrate one particular aspect of the cave, whether
it be structure or route finding or ...

If each user maintains a descriptor of his/her particular extended elevation,
he/she would hope to get the same result when the main dataset is updated.
This works fine if they list included legs, but gets extra rubbish after each
expo if they list excluded ones.

As a concrete example - suppose I had prepared an extended elevation of the
various Left Hand Routes (LHR, Powerstation, Drunk & Stupid, Pitch-Ramp) to
show their relationships. Then Expo 1999 goes off. If I had listed legs to
be excluded, then on expo's return, 2.5 km of completely unrelated stuff in
Chile would suddenly appear. This I would find undesirable.

Andy