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<div class="moz-cite-prefix">Hi Olly,<br>
<br>
El 17/05/2018 a las 0:36, Olly Betts escribió:<br>
</div>
<blockquote type="cite" cite="mid:20180516223612.GI32202@survex.com"><br>
<blockquote type="cite">
<pre wrap="">I think the formula is too complicated. I purpose a simpler formula, like:
If bearing <=180
AverageBearing = (bearing + (backbearing -180))/2
else
AverageBearing = (bearing + (backbearing +180))/2
</pre>
</blockquote>
<pre wrap="">
Your proposed formula gives wrong answers in some cases - consider:
bearing = 80, backbearing = 0
These give AverageBearing = (80 + 0 - 180) / 2 = -50 (equivalent to
310), but this should be 130 (average of 80 and 180).</pre>
</blockquote>
<br>
In this case is not a problem with my formula, is a serious magnetic
anomaly (100 degrees difference) and the program <span
id="result_box" class="short_text" lang="en"><span class="">should</span></span>
to stop and to send a warning. <br>
<br>
<blockquote type="cite" cite="mid:20180516223612.GI32202@survex.com">
<pre wrap="">
The therion formula is attempting to average the angles by trigonometry,
which seems a reasonable approach (though probably slower than trying to
average more directly like you're suggesting). It looks essentially
correct to me, though it's a bit oddly written since cos(90 - x) is
sin(x), sin(90 - x) is -cos(x), 90 - atan2(y,x) is atan2(x,y) (possibly
+/- a multiple of 360). But if I work it out with a calculator for
236.8 and 56.8 then I do get 236.8.</pre>
</blockquote>
<br>
In the afternoon I have detected a strong anomaly problem in one
station and corrected manually the data. Now the loop error is
similar to Auriga and Compass (2.9m for a 1967m loop). But I have to
check if Therion do the correct average calculation. <br>
<br>
<br>
<blockquote type="cite" cite="mid:20180516223612.GI32202@survex.com">
<pre wrap="">If it's still not working with the declination set to zero, perhaps
you should show us a complete small example we can process to see
what is going on?
</pre>
</blockquote>
<p>I attach the original file with the fore/back sight (SCAGUA.th)
and a manually averaged (SCAGUA_avg.th) to compare if Survex and
Therion work well. The error loop is similar between the two files
(2,9m) but I have to check if the station are positioned at the
same coordinates. <br>
</p>
<p>Regards,</p>
<p>Evaristo. <br>
</p>
<p><br>
</p>
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