Right, this looks promising. I have been changing projections and then enabling the grid decoration which is always oriented straight up regardless of the projection.
I assume that you were inserting your grids as a vector feature using a drawing tool? What was the CRS of the grid layer? I have been changing the project projection with OTF on. Maybe I should be adjusting the projection of the layer in question? Thanks again . . . Cheers . . . . . Spring Samsung Tab 4 On Apr 4, 2018 5:23 AM, "Kristian Evers" <[email protected]> wrote: > I had a quick go at it after I wrote the email. What I did was to first > create a custom projection with the proj-string “+proj=merc”. Then I opened > the layout editor, inserted my map and added to sets of grid lines to the > map. One of them was left with the original CRS (the UTM one) and for the > other I used my custom CRS. This immediately gave me two grids, one where > the meridians is oriented at the grid north (black in the attached image) > and one oriented at true north (red in the attached image). > > > > /Kristian > > > > *Fra:* Springfield Harrison [mailto:[email protected]] > *Sendt:* 3. april 2018 22:52 > *Til:* [email protected]; Kristian Evers <[email protected]> > *Emne:* Re: [Qgis-user] True North > > > > OK, that sounds like the solution I'm looking for. > > It sounds like the answer is to draw the lines in one projection and then > transform it to the other, depending upon which orientation is desired for > those lines. > > I hope I have this correct… > > Cheers . . . . . Springfield Harrison > > > > On 03-Apr-2018 02:46, Kristian Evers wrote: > > You can use the Mercator projection to digitize true north lines. It is > conformal and thus preserves angles. The meridian convergence is 0 (that > is, true north == grid north) all over the map. If you then transform those > lines to your chosen CRS you should have a set of lines pointing towards > true north instead of grid north. > > > > /Kristian > > > > *Fra:* Qgis-user [mailto:[email protected] > <[email protected]>] *På vegne af *Alexandre Neto > *Sendt:* 3. april 2018 11:15 > *Til:* Springfield Harrison <[email protected]> <[email protected]> > *Cc:* qgis-user <[email protected]> <[email protected]> > *Emne:* Re: [Qgis-user] True North > > > > Maybe something like this : > > > > https://gis.stackexchange.com/q/115531/6191 > > > > Alexandre > > A ter, 3/04/2018, 10:11, Alexandre Neto <[email protected]> escreveu: > > Ah sorry, > > > > I got lost in translation. You are right, I was talking about the magnetic > north, not the geodetic one. > > > > Meanwhile, remembering that all UTM are Transverse Mercator, I don't > think there's a CRS that will solve you question. > > > > 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. > > > > Alexandre > > > > A ter, 3/04/2018, 09:25, Springfield Harrison <[email protected]> > escreveu: > > 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" <[email protected]> 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 <[email protected]> > 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 > > > _______________________________________________ > Qgis-user mailing list > [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > > -- > > Alexandre Neto > > --------------------- > > @AlexNetoGeo > > http://sigsemgrilhetas.wordpress.com > > http://gisunchained.wordpress.com > > -- > > Alexandre Neto > > --------------------- > > @AlexNetoGeo > > http://sigsemgrilhetas.wordpress.com > > http://gisunchained.wordpress.com > > -- > > Alexandre Neto > > --------------------- > > @AlexNetoGeo > > http://sigsemgrilhetas.wordpress.com > > http://gisunchained.wordpress.com > > > > [image: Billede fjernet af afsender.] > <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> > > Virus-free. www.avg.com > <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> > > > > > _______________________________________________ > > Qgis-user mailing list > > [email protected] > > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > > >
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