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

[afishindouban]

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
>>
>>
>>
>> --
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>>
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