Converting between true north, grid north, and magnetic north

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Converting between true north, grid north, and magnetic north

 Hi,Is there a way to convert between grid north, true north and magnetic north in Proj4 or another library?Cheers,Chen _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj
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Re: Converting between true north, grid north, and magnetic north

 The magnetic north varies from location to location is not easy to handle, but you can get deviation from grid north using the -V option to proj:\$  echo 12 55 | proj -V +proj=utm +zone=32 +ellps=GRS80#Universal Transverse Mercator (UTM)#    Cyl, Sph#    zone= south# +proj=utm +zone=32 +ellps=GRS80#--- following specified but NOT used# +ellps=WGS84#Final Earth figure: ellipsoid#  Major axis (a): 6378137.000#  1/flattening: 298.257222#  squared eccentricity: 0.006694380023 Longitude: 12dE [ 12 ]Latitude:  55dN [ 55 ]Easting (x):   691875.63Northing (y):  6098907.83Meridian scale (h) : 1.00005168  ( 0.005168 % error )Parallel scale (k) : 1.00005168  ( 0.005168 % error )Areal scale (s):     1.00010336  ( 0.01034 % error )Angular distortion (w): 0.000Meridian/Parallel angle: 90.00000Convergence : 2d27'29.52" [ 2.45819987 ]Max-min (Tissot axis a-b) scale error: 1.00005 1.00005Where the convergence (here 2.45819987) is what you need, if I understand your question correctly.See the reply by Martin F over at https://gis.stackexchange.com/questions/61743/applying-proper-conversion-from-true-to-grid-bearing for instructions of how to apply this.2018-01-30 12:42 GMT+01:00 Chen Barnoy :Hi,Is there a way to convert between grid north, true north and magnetic north in Proj4 or another library?Cheers,Chen _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj
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Re: Converting between true north, grid north, and magnetic north

 The Geodesy & Geophysics web page at the NGA.mil site has the Isogonic (magnetism) model that can be downloaded. Sent from Cliff Mugnier's iPhone On Jan 30, 2018, at 6:37 AM, Thomas Knudsen <[hidden email]> wrote: The magnetic north varies from location to location is not easy to handle, but you can get deviation from grid north using the -V option to proj: \$  echo 12 55 | proj -V +proj=utm +zone=32 +ellps=GRS80 #Universal Transverse Mercator (UTM) #    Cyl, Sph #    zone= south # +proj=utm +zone=32 +ellps=GRS80 #--- following specified but NOT used # +ellps=WGS84 #Final Earth figure: ellipsoid #  Major axis (a): 6378137.000 #  1/flattening: 298.257222 #  squared eccentricity: 0.006694380023   Longitude: 12dE [ 12 ] Latitude:  55dN [ 55 ] Easting (x):   691875.63 Northing (y):  6098907.83 Meridian scale (h) : 1.00005168  ( 0.005168 % error ) Parallel scale (k) : 1.00005168  ( 0.005168 % error ) Areal scale (s):     1.00010336  ( 0.01034 % error ) Angular distortion (w): 0.000 Meridian/Parallel angle: 90.00000 Convergence : 2d27'29.52" [ 2.45819987 ] Max-min (Tissot axis a-b) scale error: 1.00005 1.00005 Where the convergence (here 2.45819987) is what you need, if I understand your question correctly. See the reply by Martin F over at https://gis.stackexchange.com/questions/61743/applying-proper-conversion-from-true-to-grid-bearing for instructions of how to apply this. 2018-01-30 12:42 GMT+01:00 Chen Barnoy : Hi, Is there a way to convert between grid north, true north and magnetic north in Proj4 or another library? Cheers, Chen _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj
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Re: Converting between true north, grid north, and magnetic north

 In reply to this post by Chen Barnoy GeographicLib https://geographiclib.sourceforge.io provides access to several magnetic models via the MagneticField utility.  E.g.,    echo 42.363 -71.006 | MagneticField -t now =>    -14.67 67.08 20228.0 19569.1 -5121.1 47840.0 51940.7 The first number is the current magnetic declination at Boston Logan Airport using the wmm2015 magnetic model. The magnetic models need to be downloaded separately from the GeographicLib library using    geographiclib-get-magnetic On 01/30/18 06:42, Chen Barnoy wrote: > Hi, > > Is there a way to convert between grid north, true north and magnetic > north in Proj4 or another library? > > Cheers, > Chen > > > _______________________________________________ > Proj mailing list > [hidden email] > http://lists.maptools.org/mailman/listinfo/proj> _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj
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Re: Converting between true north, grid north, and magnetic north

 Be aware that the magnetic field is time varying.  It can change pretty quickly near the magnetic poles.Yet another source... igrf.pyOn Tue, Jan 30, 2018 at 7:03 AM, Charles Karney wrote:GeographicLib https://geographiclib.sourceforge.io provides access to several magnetic models via the MagneticField utility.  E.g.,    echo 42.363 -71.006 | MagneticField -t now =>    -14.67 67.08 20228.0 19569.1 -5121.1 47840.0 51940.7 The first number is the current magnetic declination at Boston Logan Airport using the wmm2015 magnetic model. The magnetic models need to be downloaded separately from the GeographicLib library using    geographiclib-get-magnetic On 01/30/18 06:42, Chen Barnoy wrote: > Hi, > > Is there a way to convert between grid north, true north and magnetic > north in Proj4 or another library? > > Cheers, > Chen > > > _______________________________________________ > Proj mailing list > [hidden email] > http://lists.maptools.org/mailman/listinfo/proj > _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj -- _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj
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Re: Converting between true north, grid north, and magnetic north

 Or GMT that even provides an estimate of daily variation.https://gmt.soest.hawaii.edu/doc/5.4.3/supplements/mgd77/mgd77magref.htmlOn Tue, Jan 30, 2018 at 9:59 PM, Kurt Schwehr wrote:Be aware that the magnetic field is time varying.  It can change pretty quickly near the magnetic poles.Yet another source... igrf.pyOn Tue, Jan 30, 2018 at 7:03 AM, Charles Karney wrote:GeographicLib https://geographiclib.sourceforge.io provides access to several magnetic models via the MagneticField utility.  E.g.,    echo 42.363 -71.006 | MagneticField -t now =>    -14.67 67.08 20228.0 19569.1 -5121.1 47840.0 51940.7 The first number is the current magnetic declination at Boston Logan Airport using the wmm2015 magnetic model. The magnetic models need to be downloaded separately from the GeographicLib library using    geographiclib-get-magnetic On 01/30/18 06:42, Chen Barnoy wrote: > Hi, > > Is there a way to convert between grid north, true north and magnetic > north in Proj4 or another library? > > Cheers, > Chen > > > _______________________________________________ > Proj mailing list > [hidden email] > http://lists.maptools.org/mailman/listinfo/proj > _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj -- _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj
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Re: Converting between true north, grid north, and magnetic north

 In reply to this post by Kurt Schwehr-2 Thanks!And is there a similar library to convert between grid\UTM north to true north?2018-01-30 23:59 GMT+02:00 Kurt Schwehr :Be aware that the magnetic field is time varying.  It can change pretty quickly near the magnetic poles.Yet another source... igrf.pyOn Tue, Jan 30, 2018 at 7:03 AM, Charles Karney wrote:GeographicLib https://geographiclib.sourceforge.io provides access to several magnetic models via the MagneticField utility.  E.g.,    echo 42.363 -71.006 | MagneticField -t now =>    -14.67 67.08 20228.0 19569.1 -5121.1 47840.0 51940.7 The first number is the current magnetic declination at Boston Logan Airport using the wmm2015 magnetic model. The magnetic models need to be downloaded separately from the GeographicLib library using    geographiclib-get-magnetic On 01/30/18 06:42, Chen Barnoy wrote: > Hi, > > Is there a way to convert between grid north, true north and magnetic > north in Proj4 or another library? > > Cheers, > Chen > > > _______________________________________________ > Proj mailing list > [hidden email] > http://lists.maptools.org/mailman/listinfo/proj > _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj -- _______________________________________________ Proj mailing list [hidden email] http://lists.maptools.org/mailman/listinfo/proj