Hi, Is this what you need?
http://plugins.qgis.org/plugins/AzimuthDistanceCalculator/version/2.0/ Just stumbled on the description of this plugin and it mention that it can calculate the convergence for UTM. Hope it helps. Alexandre Neto A qua, 4/04/2018, 22:56, Springfield Harrison <[email protected]> escreveu: > hello Kristian, > > Thanks again for your help, I was partially successful. The second grid, > the custom Mercator one that you described is not happy in the print > composer. It does not persist but seems to revert back to the UTM grid with > the word change on the CRS button. > > Not sure what that is all about but my main requirement is to be able to > draw lines at specific angles with reference to true north. They will then > be re -projected correctly based on the display projection. Unfortunately, > the advanced digitizing tool does not work with Geographic projections, IE > un projected Maps. > > If I can get lines that are guaranteed to be related to Geographic > bearings, I could let the projection quirks sort themselves out on their > own. > > If you have any thoughts on this I would be most appreciative... > > Cheers . . . . . Spring > Samsung Tab 4 > On Apr 4, 2018 9:41 AM, "Springfield Harrison" <[email protected]> > wrote: > >> Okay, great. That is very helpful, I will work in the map composer. I >> know what you are referring to there. Thanks again... >> >> Cheers . . . . . Spring >> Samsung Tab 4 >> On Apr 4, 2018 9:36 AM, "Kristian Evers" <[email protected]> wrote: >> >>> I made it within the Layout Composer/Editor (what it’s called in QGIS3 >>> escapes me now – it used to be Map Composer in 2.x). That was the simplest >>> way to achieve it quickly I found. You have the possibility to add more >>> than one graticule and you can also change the CRS of the graticule. That >>> is what I did. One was kept in UTM, the other used my custom Mercator CRS. >>> >>> >>> >>> This is just one way of doing it. There many ways to achieve the same >>> thing, but this should outline the general idea at least. >>> >>> >>> >>> My last post was not let through to the mailing list, so here’s a copy >>> of the image I attached in the previous mail. Should anyone be interested… >>> >>> >>> >>> /Kristian >>> >>> >>> >>> >>> >>> *Fra:* Springfield Harrison [mailto:[email protected]] >>> *Sendt:* 4. april 2018 16:19 >>> *Til:* Kristian Evers <[email protected]> >>> *Cc:* qgis-user <[email protected]> >>> *Emne:* Re: SV: [Qgis-user] True North >>> >>> >>> >>> 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 >>> >>> >>> >>> _______________________________________________ > 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
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