[Therion] Multiple fixes for the same point

[Wookey]

On 2017-09-07 13:07 +0100, Andrew Atkinson via Therion wrote:
> I'm sure that this has been covered, but I cannot find it anywhere.
> 
> I have 3 different gps results for a surface point, all taken with the
> same gps but on different days, so rather then picking one I just used
> fix on all 3.
> 
> However, therion appears to be taking only the last one I enter.
> This does not seem to be the right behaviour! Is there a way for Therion
> to take all 3 and 'average' them?

I've wanted to do this too, but wasn't sure how.

From *FIX on https://survex.com/docs/manual/datafile.htm

 The standard errors default to zero (fix station exactly). cavern
 will give an error if you attempt to fix the same survey station
 twice at different coordinates, or a warning if you fix it twice with
 matching coordinates.

 You can also specify just one standard error (in which case it is
 assumed equal in X, Y, and Z) or two (in which case the first is
 taken as the standard error in X and Y, and the second as the
 standard error in Z).

So I just checked and if you add some variances you can then give more than one set of locations for it without getting errors, and the final location is the average.

Alternatively you can give them different names (with variances), then equate them.

So survex can do the right thing. Hopefully therion will pass this
through so that it works right, but I've not tested that.

So this works:
*fix pt1 5 5 5   1 1 1
*fix pt1 5 5.5 5 1 1 1

dump3d fixtest.3d:
ERROR_INFO #legs 2, len 0.00m, E 0.20 H 0.25 V 0.00
NODE 5.00 5.25 5.00 [pt1] FIXED

And so does this:
*fix pt1_1 5 5 5   1 1 1
*fix pt1_2 5 5.5 5 1 1 1
*equate pt1_1 pt1_2

dump3d fixtest.3d:
ERROR_INFO #legs 2, len 0.00m, E 0.20 H 0.25 V 0.00
NODE 5.00 5.25 5.00 [pt1_1] FIXED
NODE 5.00 5.25 5.00 [pt1_2] FIXED


Wookey
-- 
Principal hats:  Linaro, Debian, Wookware, ARM
http://wookware.org/
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