Fw: Surveys without centrelines

[Wookey]

This was posted to the therion list, but is really a survex question. 

> Stelios Zacharias <stelios.zacharias at selas.org> wrote:

> Can Therion put together scraps on the basis of the polygonal system
> of survey? (I think this is what it is called - it uses as set of
> triangles and only distance measurement rather than the distance,
> azimuth, slope measurements we are used to).
> 
> A friend has a survey constructed with only distances taken from two
> points (and successive points) so as to create a flat area of
> triangles (it is flat because the "floor" is the sea and the water
> level is constant). There is therefore no centreline, but a series of
> points, each joined by two measurements to other points and all coming
> back to a known baseline. In the days of paper survey, the plan would
> be drawn with just a compass from one point to the next, beginning off
> the baseline.


Survex has a 
*data cylpolar from to tape compass fromdepth todepth
entry form, which is along the right lines, but that
still expects bearings and depths.

As Bruce suggests, guessing the bearnings (or putting in arbitrary
values) and turning the SD up with 
*sd bearing 180 degrees
might reuslt in the right answer.

Better would be a new input format for this form of data
*data triangulation from to length fromdepth todepth
and probably more usefully
*data triangulation station depth newline tape

I'm not sure how hard it is to add this. (Is it just a new data
format, or do the solver algorithms have to change?) If the former it
should be quite straightforward.


Wookey
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