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<p>The central meridian in each utm zone is oriented directly at
true north (Easting of 500,000 m). The difference in angles when
you move east of west of the meridian is referred to as
convergence and the following link provides 2 formulas for
calculating the convergence angles in utm projections. A quick
search on convergence calculators or methods should also provide
some tools.</p>
<p><a class="moz-txt-link-freetext" href="https://gis.stackexchange.com/questions/115531/how-to-calculate-grid-convergence-true-north-to-grid-north">https://gis.stackexchange.com/questions/115531/how-to-calculate-grid-convergence-true-north-to-grid-north</a><br>
</p>
<p>Kirk<br>
</p>
<br>
<div class="moz-cite-prefix">On 4/3/2018 5:25 AM, Springfield
Harrison wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAB9q9oe7GqJfKRhWMP=d-k-G88aUe1Amfb0d0EcV+CWOMLk13g@mail.gmail.com">
<meta http-equiv="Context-Type" content="text/html; charset=UTF-8">
<p dir="ltr">Alexandre,</p>
<p dir="ltr"> I believe that true north is actually a constant
oriented towards the North Pole, i e 90 degrees north latitude.
Also where all meridians converge in the northern hemisphere.</p>
<p dir="ltr">The other North orientations are magnetic north and
grid North and these do vary as you suggested.</p>
<p dir="ltr">I do need to use a UTM projection but need bearings
to be in degrees true north.</p>
<p dir="ltr">Thanks Alexandre...</p>
<p dir="ltr">Cheers . . . . . Spring<br>
Samsung Tab 4</p>
<div class="gmail_quote">On Apr 2, 2018 4:27 PM, "Alexandre Neto"
<<a href="mailto:senhor.neto@gmail.com"
moz-do-not-send="true">senhor.neto@gmail.com</a>> wrote:<br
type="attribution">
<blockquote class="gmail_quote">AFAIK, true bearing differs in
time and location because of magnetic declination. So I don't
think there is a such thing as a CRS with true bearings.
<div><br>
</div>
<div>Assuming you are working at regional level, find the
magnetic declination for that region and remove it from your
observations. Then draw the azimuth using the chosen CRS. I
think 26910 will work just fine. </div>
<div><br>
</div>
<div>If you are at a larger scale, then you may need to use
different magnetic declination values for each observation. </div>
<div><br>
</div>
<div>This may help:</div>
<div><br>
</div>
<div><a
href="https://www.ngdc.noaa.gov/geomag/declination.shtml"
target="_blank" moz-do-not-send="true">https://www.ngdc.noaa.gov/<wbr>geomag/declination.shtml</a></div>
<div><br>
</div>
<div>Best Regards, </div>
<div><br>
</div>
<div>Alexandre Neto <br>
<br>
<div class="gmail_quote">
<div dir="ltr">A seg, 2/04/2018, 23:54, Springfield
Harrison <<a href="mailto:stellargps@gmail.com"
target="_blank" moz-do-not-send="true">stellargps@gmail.com</a>>
escreveu:<br>
</div>
<blockquote class="gmail_quote">Hello,<br>
<br>
I am using CRS 26910, NAD83 / UTM zone 10N, and need to
draw lines at<br>
exact true bearings. The Advanced Digitizing Tool seems
to do this but<br>
which CRS would I use to ensure that the bearing is
True?<br>
<br>
Thanks very much . . .<br>
<br>
<br>
Cheers . . . . . Springfield Harrison<br>
<br>
<br>
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-- <br>
<div dir="ltr" class="m_-2804556623950154024gmail_signature"
data-smartmail="gmail_signature">
<div dir="ltr">
<div>Alexandre Neto</div>
<div>---------------------</div>
<div>@AlexNetoGeo</div>
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target="_blank" moz-do-not-send="true">http://sigsemgrilhetas.<wbr>wordpress.com</a></div>
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<br>
<pre class="moz-signature" cols="72">--
Kirk Schmidt, MScF, BScF, RPF
General Manager
Nortek Resource Solutions Inc.
RR # 1
Thorburn, NS
B0K 1W0
Tel (902) 922.3607
Email: <a class="moz-txt-link-abbreviated" href="mailto:kirk@nortekresources.com">kirk@nortekresources.com</a>
Web: <a class="moz-txt-link-abbreviated" href="http://www.nortekreources.com">www.nortekreources.com</a></pre>
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