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<div class="moz-cite-prefix">OK, thank you. That formula is useful.<br>
<br>
I assume that "North" for any projection will be grid North so
that a line drawn at 0° while using a UTM projection will point to
grid North if the drawing is re-projected using an un-projected
CRS (where 0° is true North)?<br>
<br>
I wonder if I have that correct? I will check some of the other
responses also.<br>
<br>
Thanks very much…<br>
<br>
<div class="moz-signature">Cheers . . . . . Spring Harrison<br>
<br>
<br>
</div>
On 03-Apr-2018 02:15, Alexandre Neto wrote:<br>
</div>
<blockquote
cite="mid:CA+H0G_FTJX1quXJh642TDysUsAgHQYbLy_QrmeCEkkRBMjfXDQ@mail.gmail.com"
type="cite">Maybe something like this :
<div><br>
</div>
<div><a moz-do-not-send="true"
href="https://gis.stackexchange.com/q/115531/6191">https://gis.stackexchange.com/q/115531/6191</a></div>
<div><br>
</div>
<div>Alexandre<br>
<br>
<div class="gmail_quote">
<div dir="ltr">A ter, 3/04/2018, 10:11, Alexandre Neto <<a
moz-do-not-send="true" href="mailto:senhor.neto@gmail.com">senhor.neto@gmail.com</a>>
escreveu:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Ah sorry,
<div><br>
</div>
<div>I got lost in translation. You are right, I was talking
about the magnetic north, not the geodetic one.</div>
<div><br>
</div>
<div>Meanwhile, remembering that all UTM are Transverse
Mercator, I don't think there's a CRS that will solve you
question.</div>
<div><br>
</div>
<div>I think you need to use some formula to convert the
grid north measures to true north according to the CRS,
and the latitude and longitude of the place. </div>
<div><br>
</div>
<div>Alexandre </div>
<div><br>
<br>
<div class="gmail_quote">
<div dir="ltr">A ter, 3/04/2018, 09:25, Springfield
Harrison <<a moz-do-not-send="true"
href="mailto:stellargps@gmail.com" target="_blank">stellargps@gmail.com</a>>
escreveu:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<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>
</p>
<p dir="ltr">
Samsung Tab 4</p>
<div class="gmail_quote">On Apr 2, 2018 4:27 PM,
"Alexandre Neto" <<a moz-do-not-send="true"
href="mailto:senhor.neto@gmail.com"
target="_blank">senhor.neto@gmail.com</a>>
wrote:<br type="attribution">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">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 moz-do-not-send="true"
href="https://www.ngdc.noaa.gov/geomag/declination.shtml"
target="_blank">https://www.ngdc.noaa.gov/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
moz-do-not-send="true"
href="mailto:stellargps@gmail.com"
target="_blank">stellargps@gmail.com</a>>
escreveu:<br>
</div>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">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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