Survex for scuba dive surveys

[Henrik Brautaset Aronsen]

On Mon, Apr 13, 2015 at 4:49 PM, Wookey <wookey at wookware.org> wrote:

> +++ Henrik Brautaset Aronsen [2015-04-13 16:23 +0200]:
> > So it parses the comments as well?
>
> No, that was the point. It can only use dates entered with *date.
>

Aha! Good. I was afraid there was some magic comment parsing that disabled
the *date parsing :)

> *data diving from to length bearing fromdepth todepth
> > A B 25 160 12 16
> > B C 12 120 16 20
> >
> > The depth bar goes from 4m to 8m.  How do I make it go from 12 to 20?
>
> Start your survey from 0m depth, not from 12m down :-)
>

It's not possible to start it at 12m?  I've surveyed a line that starts at
12m depth, which is beyond the "cavern" zone.  (Cavers and divers have
different interpretations of "cavern", but still...)


> If nothing else is specified survex starts the first station at 0,0,0
> so in this case the second station is 4m down, the second 8m down.
>
> The scale bar shows depths/altitudes within the surveyed space, not
> all space from wherever sea-level or sump-level (or other arbitrary
> zero-measurement) might be. You can see why this is sensible with a
> 30m deep cave 3km up a mountain.
>

The scale in Aven was from 4 to 8 meters, which gives a total of 4 meters.
  My data was from 12 to 20 meters, which is total of 8 meters.  So the
scale is off somehow.


> So to get what you asked for you could do:
> *fix surface 0 0 -12
> A B 25 160 -12 -16
> B C 12 120 -16 -20
>
> so surfex fixes the first stn at 0,0,-12 instead of the default 0,0,0
>

Now I get «Unused fixed point “surface”», probably since I haven't
connected it to anything.

If I instead just put A at 0 meters, the scale in Aven goes from -16 to -20:

A B 25 160 0 -16
B C 12 120 -16 -20

The color coding seems to indicate that pt A is at -16m:
https://www.dropbox.com/s/x556vj6w0ax6aoi/survex.png?dl=0

I'm confused.  Sorry for asking silly questions :/

Henrik