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Hello Monks !

I have a question of regarding to calculate headings of several aircrafts movements from a series of GPS data, then i can use perl subroutine to convert the code into kml and display it on GoogleEarth, so the aircraft icon could rotate as time shifts.

i have already written some code to convert the code to kml, but not the headings, i know the method i should use to calculate the heading is something like following (very crude method), but i don't know how to implement into perl. it needs to use kind of array to store current point and way point, then computer the headings from two points.

I need helps, any clever Perlmonks out there could provide me some wisdom. below provide code i written so far and input data sample

Many thanks in advance !

Psuedo code for heading calculation

  dlat = lat2 - lat1 
  dlon = lon2 - lon1 
  y = sin(lon2-lon1)*cos(lat2)
  x = cos(lat1)*sin(lat2)-sin(lat1)*cos(lat2)*cos(lon2-lon1)
  if y > 0 then
    if x > 0 then tc1 = arctan(y/x)
    if x < 0 then tc1 = 180 - arctan(-y/x)
    if x = 0 then tc1 = 90
  if y < 0 then
    if x > 0 then tc1 = -arctan(-y/x)
    if x < 0 then tc1 = arctan(y/x)-180
    if x = 0 then tc1 = 270
  if y = 0 then
    if x > 0 then tc1 = 0
    if x < 0 then tc1 = 180
    if x = 0 then [the 2 points are the same]
[download]

perl code

 #!/usr/bin/perl 
use POSIX qw(ceil floor); 
open(INPUT, $infile);
@lines = <INPUT>;
close(INPUT);

open(OUTPUT, ">$outfile");

sub trim($);

$timeCounter = 0;
$seconds = 0;
$minutes = 0;
$hours = 0;
$comma = ",";
$space = " ";

print OUTPUT "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"."\n";
print OUTPUT "<kml xmlns=\"http://earth.google.com/kml/2.1\">"."\n";
print OUTPUT "<Folder>"."\n";

foreach $currentLine(@lines)
{
    
    @lineBuffer = split($delimiter,$currentLine);

    #--- At this point, we have the data from the current line.
    
    #--- Get all the elements
    $rowid              = trim(@lineBuffer[0]);
    $aircraftid         = trim(@lineBuffer[1]);    
    $actual_date_time   = trim(@lineBuffer[2]);
    #$end_time           = trim(@lineBuffer[3]);
    $latitude           = trim(@lineBuffer[3]);
    $longitude          = trim(@lineBuffer[4]); 
    $radio_altitude     = trim(@lineBuffer[5]);
    $ground_speed       = trim(@lineBuffer[6]);
    $thrust_engine_1    = trim(@lineBuffer[7]);
    $thrust_engine_2    = trim(@lineBuffer[8]);


    #--- Now, convert start and end times into UTC
    @timeString = split($space,$actual_date_time);
    $actual_date_time = @timeString[0]."T".@timeString[1];

    #--- Determine the bearing
    

    $icon = "./blue_plane.png";
    print OUTPUT "<Placemark><Style><IconStyle><scale>1.0</scale><head
+ing>90</heading><Icon><href>$icon</href></Icon></IconStyle></Style><P
+oint><coordinates>";
    print OUTPUT $longitude.$comma.$latitude.$comma.$radio_altitude;
    print OUTPUT "</coordinates><altitudeMode>relativeToGround</altitu
+deMode></Point>";
    print OUTPUT "<TimeStamp><when>$actual_date_time</when></TimeStamp
+>";
    print OUTPUT "<description>"."ID:".$rowid."<hr/>"."time:".$actual_
+date_time."<hr/>"."Ground_speed:".$ground_speed."<hr/>"."Thrust_engin
+e_1:".$thrust_engine_1."<hr/>"."thrust_engine_2:".$thrust_engine_2."<
+hr/>"."nox_total:".$nox_total."<hr/>"."co_total:".$co_total."<hr/>"."
+longitude:".$longitude."<hr/>"."latitude:".$latitude."<hr/>"."radio_a
+ltitude:".$radio_altitude."<hr/></description>";
    print OUTPUT "</Placemark>"."\n";
    }


print OUTPUT "</Folder></kml>";
[download]

Data sample of several aircraft GPS data:

"rowid","aircraft_id","actual_date_time","latitude","longitude","radio
+_altitude","ground_speed","thrust_engine_1","thrust_engine_2"
3828994,599,2012-11-04 14:00:00,51.47592545,-0.437049866,-9.0,2.0,0.04
+4653355,0.041778761,1.74208527619370935228499282740898271690901934191
+164070390564,15.22092881857486030932218666006017736321211426212568671
+811012
3828995,591,2012-11-04 14:00:00,51.47598267,-0.435331702,-0.875,0.0,0.
+066208174,0.068682498,0.913095793953437657822846430541224159086453865
+40627114668956,4.8940906898850944664550883969746212941234464464906348
+3492349
3828996,599,2012-11-04 14:00:01,51.47592545,-0.437049866,-9.0,2.0,0.04
+4653355,0.041778761,1.74208527619370935228499282740898271690901934191
+164070390564,15.22092881857486030932218666006017736321211426212568671
+811012
3828997,591,2012-11-04 14:00:01,51.47598267,-0.435331702,-0.75,0.0,0.0
+64970428,0.068682498,0.9055060385715144395793861983988312690635603870
+3789731965392,4.92096836684002218971971504299700119099094370033875757
+916224
3828998,599,2012-11-04 14:00:02,51.47592545,-0.437049866,-9.0,2.0,0.04
+4653355,0.041778761,1.74208527619370935228499282740898271690901934191
+164070390564,15.22092881857486030932218666006017736321211426212568671
+811012
3828999,591,2012-11-04 14:00:02,51.47598267,-0.435331702,-0.625,0.0,0.
+066208174,0.068682498,0.913095793953437657822846430541224159086453865
+40627114668956,4.8940906898850944664550883969746212941234464464906348
+3492349
3829000,599,2012-11-04 14:00:03,51.47592545,-0.437049866,-9.0,2.0,0.04
+4653355,0.041
[download]

In reply to Calculate aircraft headings from GPS data for google kml display by hujunsimon

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