Re: [Paparazzi-devel] log file UTM to WGS84 convert question

[Gautier Hattenberger]

Hi,

I have tested a few online converters for your UTM coordinates:
39.502741,                  116.50624594826415
39.50274,                    116.50625
39.50274153051662,  116.50624594824883
-> they seem to agree

pprz was
39.502822146,            116.506218394
perl was
39.5046274995347,    116.506245384612
-> they are both different, but your latitude is really far compared to pprz

I think the error comes from the geodetic model, we are using WGS84 and 
you have set Clarke1880. Change the first parameter of the 
utm_to_latlong from 5 to 23 and try again.

Gautier

Le 04/08/2014 20:36, afishindouban a écrit :
> I use perl to make convert, and result is different to the PPZ log plotter
> save to CVS latlong value. the different is always around tens meters. Its
> really strange.
>
> Can you help me to verified what is wrong ?
> for example.
>
> this is one msg in data file.
> 1832.0000 3 DC_SHOT 309 45754908 437268512 283.967987 50 -15 20 1735 1706
> 369775500
>
> PPZ log plotter CVS latlong output is lat 39.502822146, long 16.506218394
>
> But if you use Perl Geo::Coordinates::UTM
> (http://search.cpan.org/~grahamc/Geo-Coordinates-UTM-0.11/UTM.pm#utm_to_latlon)
> to convert.
> Perl file:
>
> #!/usr/bin/perl
> #To use the Geo::Coordinates::UTM module first you must install it, see
> below
> eval {#use the require and import instead of 'use Geo::Coordinates::UTM;'
>        #so that we can print an error message
>        require Geo::Coordinates::UTM;
>        import  Geo::Coordinates::UTM;
>        1;
> } || die("
> Cannot load Geo::Coordinates::UTM --
> please execute:
>    perl -MCPAN -e 'install Geo::Coordinates::UTM'
> ");
>
> my $utm_x = 457549.08;
> my $utm_y = 4372685.12;
> my $utm_z = "50S";
>
> print "Convert \$utm_x, \$utm_y, \$utm_z =$utm_x, $utm_y, $utm_z\n";
> my ($lat, $lon) = utm_to_latlon(5, $utm_z, $utm_x, $utm_y);
> print "Result \$lat, \$lon=$lat,$lon\n";
> exit();
>
>
> the result is
>
> Convert $utm_x, $utm_y, $utm_z =457549.08, 4372685.12, 50S
> Result $lat, $lon=39.5046274995347,116.506245384612
>
>
> You can see Lat and Long is different, and the distance of of the result is
> about tens meters.
>
> Where is the mistake ??? Please try to use this perl script to convert any
> UTM address . to compare with ppz log plotter output.
>
> Thanks........
>
>
>
>
> Andreas wrote
> > Hi Kevin,
> >
> > the letter for the latitudonal 8-degree band (T, R or S) may be
> > calculated after converting UTM to WGS84. It is insignificant for that,
> > since the utm_y is always the distance from the equator. For the utm_x
> > value where you need the zone number (e.g. 50) this is different since
> > it is the distance for the central meridian which depends on the zone.
> > The letter describing the latitudonal band is just cosmetics. You can
> > determine it after conversion to geographical coordinates:
> >
> > the letters are "CDEFGHJKLMNPQRSTUVWXX" from 80 deg south in increasing
> > order for each 8-deg-band. However there are exceptions over
> > Scandinavia. May be better use a tool like:
> >
> > http://trac.osgeo.org/proj/
> >
> > linux pakage: proj-bin
> >
> > Andreas
> >
> >
> >
> > Am 07.07.2014 03:17, schrieb afishindouban:
> > > Hi everyone
> > >
> > > sorry for bother you, I have a confuse about log file pos covert.
> > >
> > > for example one line in a log file could be
> > >
> > > 130.5000 3 GPS 3 45628136 437386560 2918 20626 5 -6 1799 368074000 50 28
> > >
> > > so the utm_x=45628136 utm_y=437386560 utm_zone=50, but it should say 50T,
> > > 50R or 50S for I can use UTM2WGS84 convertor. How can I get this
> > > information
> > > by a log file ?
> > >
> > > Please help me. thanks a lot.
> > >
> > > Kevin
> > >
> > >
> > >
> > > --
> > > View this message in context:
> > > http://lists.paparazziuav.org/log-file-UTM-to-WGS84-convert-question-tp15775.html
> > > Sent from the paparazzi-devel mailing list archive at Nabble.com.
> > >
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>
>
> --
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