[Therion] Export Full Backbearings from PocketTopo to Therion

[Footleg]

That is all very interesting and useful John.

I have been in the habit of firing just a single splay shot back as my
back bearings. I did not know PocketTopo treated back bearings like
you describe. With my method the back bearing is just treated like any
other splay. So it does not affect the primary loop closures (in
Survex) or generate back bearing errors automatically. But the
information is there for future reference. Primarily I have used it on
the spot during the survey to spot bad legs and re-measure them at the
time on the survey.

But I am in the process of enhancing my caveconverter software to deal
with splays in various ways. Generating LRUD dimensions from splays
for model generation (again primarily for Survex) but also thinking
about how to handle the back shots. I am not aware of specific support
for flagging a shot as a back shot in either Survex or Therion. But I
was intending to at least implement support for such a flag in my in
memory data model so I have the option to output the information in
future to files which do support it, but also to give options for what
to do with it in exported files now (e.g. Export as a commented out
leg, export as duplicate legs, export as splays) or just to help
visualise data errors better (I have not started on data visualisation
yet, but have been thinking about it for a while).

Footleg

On 29 August 2013 12:12, John Stevens <john at k-stevens.co.uk> wrote:
> Export oddities from PocketTopo to Therion
>
> A while back, I noted that if you do a full back bearing of three readings
> straight after you have done to forward leg, PocketTopo recognises this as
> the same leg and numbers it accordingly. I have not found any documentation
> about this useful feature though.
>
>     2.10                  1.139   64.25  -33.70  [1]
>
>      2.10                  1.288   53.85  -61.89  [1]
>
>      2.10                  2.243  304.70  -50.40  [1]    "fissure in floor
> with sound of water flowing "
>
>      2.10        2.11      3.574   49.25  -15.19  [1]
>
>      2.10        2.11      3.574   49.06  -15.19  [1]
>
>      2.10        2.11      3.577   49.27  -15.23  [1]
>
>      2.11        2.10      3.576  229.26   14.68  [1]
>
>      2.11        2.10      3.575  229.37   14.68  [1]
>
>      2.11        2.10      3.577  229.60   14.80  [1]
>
>      2.11                  0.599   96.53   74.98  [1]
>
>      2.11                  0.201  156.69  -50.20  [1]
>
>
>
> If the back bearing was outside the automatic parameters, then it can always
> be forced and sorted later. i.e. make a note, station may be too close to
> iron work or buried iron in spoil/deads.
>
>
>
> PocketTopo and TopParser deal with these in different ways when it is
> imported into Therion
>
>
>
> PocketTopo averages all 6 readings for the output file but it also adds a
> blank line
>
>
>
> 2.10                        64.25     -33.68    1.140     >
>
> 2.10                        53.85     -61.89    1.288     >
>
> 2.10                        304.69   -50.39    2.243     >
>
> 2.10        2.11        49.30     -14.96    3.575     >
>
> 2.11        2.10        0.00        0.00        0.000     >
>
> 2.11                        96.67     75.01     0.599     >
>
> 2.11                        156.63   -50.15    0.201     >
>
>
>
> This second line then has to be commented out or deleted once in Therion.
> Other than that all other outputs act as expected.
>
>
>
> TopParser on the other hand outputs both sets of readings as separate legs.
> This has an advantage but a couple of disadvantages.
>
>
>
> 2.10  -  1.139  64.25  -33.7
>
> 2.10  -  1.288  53.85  -61.89
>
> 2.10  -  2.243  304.7  -50.4  fissure in floor with sound of water flowing
>
> #2.10  2.11  3.574  49.25  -15.19
>
> #2.10  2.11  3.574  49.06  -15.19
>
> #2.10  2.11  3.577  49.27  -15.23
>
> 2.10  2.11  3.575  49.15  -15.2  Calculated leg from 3 above
>
> #2.11  2.10  3.576  229.26  14.68
>
> #2.11  2.10  3.575  229.37  14.68
>
> #2.11  2.10  3.577  229.6  14.8
>
> 2.11  2.10  3.576  229.31  14.72  Calculated leg from 3 above
>
> 2.11  -  0.599  96.53  74.98
>
> 2.11  -  0.201  156.69  -50.2
>
>
>
> If I use this output, the length of the cave is doubled for the leg but I do
> get some nice 2 leg loop closure errors.
>
> The distance can be adjusted but adding flags duplicate and flags not
> duplicate lines around the duplicate leg.
>
> These loop closures then give me good feed back into where magnetic
> influences are within the cave/mine.
>
>
>
>   5.70%    0.4m    7.7m   2   -0.2m    0.4m   -0.0m [2.7 - 2.8 - 2.7]
>
>   3.86%    0.2m    5.1m   2   -0.1m   -0.2m   -0.0m [2.8 - 2.9 - 2.8]
>
>   2.70%    0.2m    8.7m   2   -0.2m    0.2m   -0.0m [2.11 - 2.12 - 2.11]
>
>   1.18%    0.1m   11.0m   2   -0.1m   -0.1m    0.0m [2.9 - 2.10 - 2.9]
>
>   0.50%    0.0m    3.9m   2   -0.0m   -0.0m    0.0m [2.12 - 2.2 - 2.12]
>
>   0.44%    0.0m    7.2m   2   -0.0m    0.0m   -0.0m [2.10 - 2.11 - 2.10]
>
>   0.33%    0.0m   10.8m   2    0.0m    0.0m   -0.0m [2.2 - 2.7 - 2.2]
>
>
>
> From these it is easy to see which passage had a large iron pipe running
> down it, even those we kept a good distance from it. This now allows me to
> set that passage survey grade as lower for the loop closures.
>
> But with all these subloops, Therion does not like calculating the main loop
> error.
>
> The other main problem with the TopParser output is for the extended
> section. Here it plots both legs so the centreline and splays are in the
> wrong place for the drawings. So that output is totally useless and I have
> to go back and use the PocketTopo output for extended sections.
>
>
>
> So bit more work on TopParser and PocketTopo to make them both fully
> implement this useful function.
>
>
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