To compute the physical distance between landmarks from the Lats and Longs of two locations we can use this tool to compute the distance http://www.movable-type.co.uk/scripts/latlong.html.
If you have the lat longs in spreadsheet columns then you could write a function (see the attached spread sheet).
Below is a perl sub you could embed in a perl script. It assumes you have a min RTT and the lat longs of source and destination. You could also extract the code to calculate the distance.
You can get the database information (e.g. name, lat/long) on the landmarks themselves from http://www-wanmon.slac.stanford.edu/cgi-wrap/reflector.cgi?function=landmarks
################################################################################
# Calculate alpha given the lat longs of the source (monitor) and target (remote)
# hosts, together with the minimum measured RTT in msec between them.
# alpha=distance_between_monitor_and_remote(in kms)/(100*min_RTT(in msec)).
# South latitudes are negative, east longitudes are positive. They are in
# decimal degrees. 57.2958=180/pi coverts degrees to rdaians.
# True radius varies from 6357km (polar) to 6378km (equatorial).
# See http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=670&lngWId=6
# If it is not possible to calculate alpha due to an invalid RTT (e.g. no digits,
# just a period (.), then getalpha returns a period.
# Example:
# getalpha($src-latlong, $tgt_latlong, $min_rtt)
# getalpha('31.77 35.23', '9.98 -84.07', 121.223) sub getalpha {
my @monitor_latlon = split(' ', $_[0]);
my @remote_latlon = split(' ', $_[1]);
for (my $i=0;$i<2;$i++) {
unless(($remote_latlon[$i]=~/^-{0,1}\d*\.{0,1}\d+$/)
&& ($monitor_latlon[$i]=~/^-{0,1}\d*\.{0,1}\d+/)) {
return ".";
}
}
my $min_rtt = $_[2];
my $alpha;
my $min_dis=100000; #Initialise to an impossibly large value >> circumference of earth.
if (defined($min_rtt) && ($min_rtt=~/\d/) && ($min_rtt>0)) {#Is there a valid $min_rtt
my $distance=((6378.7)*(acos((sin($monitor_latlon[0]/57.2958))
*(sin($remote_latlon[0]/57.2958))+(cos($monitor_latlon[0]/57.2958))
*(cos($remote_latlon[0]/57.2958))
*(cos(($remote_latlon[1]/57.2958)-($monitor_latlon[1]/57.2958))))));
if($distance>$min_dis) {$distance=$min_dis;}
$alpha=$distance/(100*$min_rtt);
}
else {$alpha=".";}
return $alpha;
}