Re: Determine lat/lon of geo location at given distance from other location

#!/usr/bin/env perl

use strict;
use warnings;

use Geo::Ellipsoid;

print "\nUsing Geo::Ellipsoid\n";
my $gel = Geo::Ellipsoid->new(
    ellipsoid => 'WGS84',
    units => 'degrees',
    distance_units => 'meter',
    longitude => 0,
    bearing => 0,
);
my @curlatlon1 = (37.889086, 41.129166);
my @curlatlon2 = (39.668930, 66.993292);

# displacement from 1 to 2
my ($x,$y) = $gel->displacement(@curlatlon1, @curlatlon2);
print "displacement from @curlatlon1 to @curlatlon2 = ($x,$y)\n";
my @newlatlon = $gel->location(@curlatlon1, $x, $y);
print "moving from @curlatlon1 by ($x,$y) gets me to @newlatlon (corre
+ct is @curlatlon2)\n";
print "dist: ".sqrt($x*$x+$y*$y)
    .", bearing: ".180*atan2($y,$x)/3.14." degrees\n";

# from 2 to 1
($x,$y) = $gel->displacement(@curlatlon2, @curlatlon1);
print "displacement from @curlatlon2 to @curlatlon1 = ($x,$y)\n";
@newlatlon = $gel->location(@curlatlon2, $x, $y);
print "moving from @curlatlon2 by ($x,$y) gets me to @newlatlon (corre
+ct is @curlatlon1)\n";
print "dist: ".sqrt($x*$x+$y*$y)
    .", bearing: ".180*atan2($y,$x)/3.14." degrees\n";

use Geo::Calc;
print "\nUsing Geo::Calc\n";
my $cur1 = Geo::Calc->new(lat=>$curlatlon1[0], lon=>$curlatlon1[1]);
my $bear = $cur1->bearing_to({lat=>$curlatlon2[0], lon=>$curlatlon2[1]
+});
my $dist = $cur1->distance_to({lat=>$curlatlon2[0], lon=>$curlatlon2[1
+]});
my $newlatlon = $cur1->destination_point($bear, $dist);
print "from ("
    .$cur1->get_lat().",".$cur1->get_lon()
.") moving by $dist m and $bear degrees got me to ("
    .$newlatlon->{'lat'}.",".$newlatlon->{'lon'}
.")\n";
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Re^2: Determine lat/lon of geo location at given distance from other location by Aldebaran (Curate) on Jul 01, 2019 at 18:30 UTC
I've been playing with this source for several days and have mixed results to show for it. Using Geo::Ellipsoid Initial location is 50.754444 6.020833 New location is 50.7496017030457 7.08357125653985 diff is 1.06273825653985 sanity check for earth assuming a sphere ratio is 111.319444444444 km/degree distance is 118.303432307874 dist is 74.9999999999233 $ cat 2.geo.pl #!/usr/bin/env perl use 5.011; use warnings; use Geo::Ellipsoid; print "\nUsing Geo::Ellipsoid\n"; my $gel = Geo::Ellipsoid->new( ellipsoid => 'WGS84', #default value units => 'degrees', distance_units => 'kilometer', longitude => 6.020833, bearing => 0, ); my @ini_lat_lon1 = ( 50.754444, 6.020833 ); say "Initial location is @ini_lat_lon1"; my ( $x, $y ) = ( 75, 0 ); my @new_lat_lon = $gel->location( @ini_lat_lon1, $x, $y ); say "New location is @new_lat_lon"; my $diff = $new_lat_lon[1] - $ini_lat_lon1[1]; say "diff is $diff"; say "sanity check for earth assuming a sphere"; my $circum = 40075; #km my $circle = 360; #degrees my $ratio = $circum / $circle; say "ratio is $ratio km/degree"; my $distance = $diff * $ratio; say "distance is $distance"; ## trying another method # my $dist = $geo->range( @origin, @destination ); my $dist = $gel->range( @ini_lat_lon1, @new_lat_lon ); say "dist is $dist"; __END__ $ [download] My sanity check fails. The documentation warns of non-Euclidean effects: the cpan listing `NOTE: The x and y displacements are only approximations and only valid between two locations that are fairly near to each other. Beyond 10 kilometers or more, the concept of X and Y on a curved surface loses its meaning.` Also, for those who want to replicate these things, it does take a lot of time for dependencies to be satisfied. I like to know that I have it all ready to go for when I get stranded on an island in the Pacific.	[reply] [d/l] [select]

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Re^2: Determine lat/lon of geo location at given distance from other location
by Aldebaran (Curate) on Jul 01, 2019 at 18:30 UTC

I've been playing with this source for several days and have mixed results to show for it.

Using Geo::Ellipsoid
Initial location is  50.754444 6.020833
New location is  50.7496017030457 7.08357125653985
diff is 1.06273825653985
sanity check for earth assuming a sphere
ratio is 111.319444444444 km/degree
distance is 118.303432307874
dist is 74.9999999999233
$ cat 2.geo.pl
#!/usr/bin/env perl

use 5.011;
use warnings;
use Geo::Ellipsoid;

print "\nUsing Geo::Ellipsoid\n";
my $gel = Geo::Ellipsoid->new(
  ellipsoid      => 'WGS84',       #default value
  units          => 'degrees',
  distance_units => 'kilometer',
  longitude      => 6.020833,
  bearing        => 0,
);

my @ini_lat_lon1 = ( 50.754444, 6.020833 );
say "Initial location is  @ini_lat_lon1";
my ( $x, $y ) = ( 75, 0 );
my @new_lat_lon = $gel->location( @ini_lat_lon1, $x, $y );
say "New location is  @new_lat_lon";

my $diff = $new_lat_lon[1] - $ini_lat_lon1[1];
say "diff is $diff";

say "sanity check for earth assuming a sphere";
my $circum = 40075;                #km
my $circle = 360;                 #degrees
my $ratio  = $circum / $circle;
say "ratio is $ratio km/degree";
my $distance = $diff * $ratio;
say "distance is $distance";

## trying another method
# my $dist = $geo->range( @origin, @destination );
my $dist = $gel->range( @ini_lat_lon1, @new_lat_lon );
say "dist is $dist";
__END__
$
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My sanity check fails. The documentation warns of non-Euclidean effects: the cpan listing

NOTE: The x and y displacements are only approximations and only valid between two locations that are fairly near to each other. Beyond 10 kilometers or more, the concept of X and Y on a curved surface loses its meaning.

Also, for those who want to replicate these things, it does take a lot of time for dependencies to be satisfied. I like to know that I have it all ready to go for when I get stranded on an island in the Pacific.

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