[Qgis-user] True North

[Springfield Harrison]

Alexandre,

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.

The other North orientations are magnetic north and grid North and these do
vary as you suggested.

I do need to use a UTM projection but need bearings to be in degrees true
north.

Thanks Alexandre...

Cheers . . . . .   Spring
Samsung Tab 4
On Apr 2, 2018 4:27 PM, "Alexandre Neto" <senhor.neto at gmail.com> wrote:

> 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.
>
> 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.
>
> If you are at a larger scale, then you may need to use different magnetic
> declination values for each observation.
>
> This may help:
>
> https://www.ngdc.noaa.gov/geomag/declination.shtml
>
> Best Regards,
>
> Alexandre Neto
>
> A seg, 2/04/2018, 23:54, Springfield Harrison <stellargps at gmail.com>
> escreveu:
>
>> Hello,
>>
>> I am using CRS 26910, NAD83 / UTM zone 10N, and need to draw lines at
>> exact true bearings.  The Advanced Digitizing Tool seems to do this but
>> which CRS would I use to ensure that the bearing is True?
>>
>> Thanks very much . . .
>>
>>
>> Cheers . . . . . Springfield Harrison
>>
>>
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> --
> Alexandre Neto
> ---------------------
> @AlexNetoGeo
> http://sigsemgrilhetas.wordpress.com
> http://gisunchained.wordpress.com
>
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