[Therion] Survey without clino

[Tarquin Wilton-Jones]

Hi Anton,

>     data normal from to length compass clino
>     0 1 5.53 5.5 24.5

If you are trying to do a survey where you just didn't bother to take
clino readings, Survex uses "-" for the clino like this, which makes it
use 0 as the clino:

data normal from to length compass clino
0 1 5.53 5.5 -

But Therion does not understand that. You have to explicitly set the
clino to 0:

data normal from to length compass clino
0 1 5.53 5.5 0

Note that Wookey's suggestion does not work in Therion, even though
Survex understands it (Survex treats them as clino=0):

data normal from to length compass #error in Therion, it needs a clino
0 1 5.53 5.5

If, however, you are trying to do a survey where you know that the
altitude (above a certain fixed point) is v1 metres, and the next
station is v2 metres above the fixed point (eg. if you are tracing over
a survey with altitude dots, or if you measured vertical descent between
stations with a plumb line), you can use "data diving" with v1 and v2 as
the fromdepth and todepth:

data diving from to tape compass fromdepth todepth
0 1 5.53 5.5 20 22 #that is a 2 metre rise in altitude
1 2 50 37 22 -10 #that is a 32 metre fall in altitude
2 3 37 100 10 -15 #that is a 25 metre fall in altitude

Note that with this approach, it will get the altitude of the cave wrong
for exported files, unless you also set a fixed point with the correct
altitude. It uses relative altitudes, not actual altitudes. That is how
2-3 leg still manages to be connected to station 2, even though the
absolute altitudes make no sense.

Cheers,

Tarquin