Here is a quick post on converting from KML files used in Google Earth/Maps to GPX Exchange Format (GPX) with PHP.
Code is quite explanatory, change $u with the location of the KML file, code will output GPX XML.
Alternatively, download the code here.
<?php
//enter location of KML file here
$u = "http://code.google.com/apis/kml/documentation/KML_Samples.kml";
function utcdate() {
return gmdate("Y-m-d\Th:i:s\Z");
}
$u_parts = pathinfo($u); //array of url parts
$u_ext = strtoupper($u_parts['extension']);
if ($u_ext== "KML") {
$dom_kml = new DOMDocument();
$dom_kml->load($u);
$dom_gpx = new DOMDocument('1.0', 'UTF-8');
$dom_gpx->formatOutput = true;
//root node
$gpx = $dom_gpx->createElement('gpx');
$gpx = $dom_gpx->appendChild($gpx);
$gpx_version = $dom_gpx->createAttribute('version');
$gpx->appendChild($gpx_version);
$gpx_version_text = $dom_gpx->createTextNode('1.0');
$gpx_version->appendChild($gpx_version_text);
$gpx_creator = $dom_gpx->createAttribute('creator');
$gpx->appendChild($gpx_creator);
$gpx_creator_text = $dom_gpx->createTextNode('https://mectile.com');
$gpx_creator->appendChild($gpx_creator_text);
$gpx_xmlns_xsi = $dom_gpx->createAttribute('xmlns:xsi');
$gpx->appendChild($gpx_xmlns_xsi);
$gpx_xmlns_xsi_text = $dom_gpx->createTextNode('http://www.w3.org/2001/XMLSchema-instance');
$gpx_xmlns_xsi->appendChild($gpx_xmlns_xsi_text);
$gpx_xmlns = $dom_gpx->createAttribute('xmlns');
$gpx->appendChild($gpx_xmlns);
$gpx_xmlns_text = $dom_gpx->createTextNode('http://www.topografix.com/GPX/1/0');
$gpx_xmlns->appendChild($gpx_xmlns_text);
$gpx_xsi_schemaLocation = $dom_gpx->createAttribute('xsi:schemaLocation');
$gpx->appendChild($gpx_xsi_schemaLocation);
$gpx_xsi_schemaLocation_text = $dom_gpx->createTextNode('http://www.topografix.com/GPX/1/0 http://www.topografix.com/GPX/1/0/gpx.xsd');
$gpx_xsi_schemaLocation->appendChild($gpx_xsi_schemaLocation_text);
$gpx_url = $dom_gpx->createElement('url');
$gpx_url = $gpx->appendChild($gpx_url);
$gpx_url_text = $dom_gpx->createTextNode($u_parts['dirname']);
$gpx_url->appendChild($gpx_url_text);
$gpx_time = $dom_gpx->createElement('time');
$gpx_time = $gpx->appendChild($gpx_time);
$gpx_time_text = $dom_gpx->createTextNode(utcdate());
$gpx_time->appendChild($gpx_time_text);
// placemarks
$names = array();
foreach ($dom_kml->getElementsByTagName('Placemark') as $placemark) {
//name
foreach ($placemark->getElementsByTagName('name') as $name) {
$name = $name->nodeValue;
//check if the key exists
if (array_key_exists($name, $names)) {
//increment the value
++$names[$name];
$name = $name." ({$names[$name]})";
} else {
$names[$name] = 0;
}
}
//description
foreach ($placemark->getElementsByTagName('description') as $description) {
$description = $description->nodeValue;
}
foreach ($placemark->getElementsByTagName('Point') as $point) {
foreach ($point->getElementsByTagName('coordinates') as $coordinates) {
//add the marker
$coordinate = $coordinates->nodeValue;
$coordinate = str_replace(" ", "", $coordinate);//trim white space
$latlng = explode(",", $coordinate);
if (($lat = $latlng[1]) && ($lng = $latlng[0])) {
$gpx_wpt = $dom_gpx->createElement('wpt');
$gpx_wpt = $gpx->appendChild($gpx_wpt);
$gpx_wpt_lat = $dom_gpx->createAttribute('lat');
$gpx_wpt->appendChild($gpx_wpt_lat);
$gpx_wpt_lat_text = $dom_gpx->createTextNode($lat);
$gpx_wpt_lat->appendChild($gpx_wpt_lat_text);
$gpx_wpt_lon = $dom_gpx->createAttribute('lon');
$gpx_wpt->appendChild($gpx_wpt_lon);
$gpx_wpt_lon_text = $dom_gpx->createTextNode($lng);
$gpx_wpt_lon->appendChild($gpx_wpt_lon_text);
$gpx_time = $dom_gpx->createElement('time');
$gpx_time = $gpx_wpt->appendChild($gpx_time);
$gpx_time_text = $dom_gpx->createTextNode(utcdate());
$gpx_time->appendChild($gpx_time_text);
$gpx_name = $dom_gpx->createElement('name');
$gpx_name = $gpx_wpt->appendChild($gpx_name);
$gpx_name_text = $dom_gpx->createTextNode($name);
$gpx_name->appendChild($gpx_name_text);
$gpx_desc = $dom_gpx->createElement('desc');
$gpx_desc = $gpx_wpt->appendChild($gpx_desc);
$gpx_desc_text = $dom_gpx->createTextNode($description);
$gpx_desc->appendChild($gpx_desc_text);
//$gpx_url = $dom_gpx->createElement('url');
//$gpx_url = $gpx_wpt->appendChild($gpx_url);
//$gpx_url_text = $dom_gpx->createTextNode($ref);
//$gpx_url->appendChild($gpx_url_text);
$gpx_sym = $dom_gpx->createElement('sym');
$gpx_sym = $gpx_wpt->appendChild($gpx_sym);
$gpx_sym_text = $dom_gpx->createTextNode('Waypoint');
$gpx_sym->appendChild($gpx_sym_text);
}
}
}
foreach ($placemark->getElementsByTagName('LineString') as $lineString) {
foreach ($lineString->getElementsByTagName('coordinates') as $coordinates) {
//add the new track
$gpx_trk = $dom_gpx->createElement('trk');
$gpx_trk = $gpx->appendChild($gpx_trk);
$gpx_name = $dom_gpx->createElement('name');
$gpx_name = $gpx_trk->appendChild($gpx_name);
$gpx_name_text = $dom_gpx->createTextNode($name);
$gpx_name->appendChild($gpx_name_text);
$gpx_trkseg = $dom_gpx->createElement('trkseg');
$gpx_trkseg = $gpx_trk->appendChild($gpx_trkseg);
$coordinates = $coordinates->nodeValue;
$coordinates = preg_split("/[\s\r\n]+/", $coordinates); //split the coords by new line
foreach ($coordinates as $coordinate) {
$latlng = explode(",", $coordinate);
if (($lat = $latlng[1]) && ($lng = $latlng[0])) {
$gpx_trkpt = $dom_gpx->createElement('trkpt');
$gpx_trkpt = $gpx_trkseg->appendChild($gpx_trkpt);
$gpx_trkpt_lat = $dom_gpx->createAttribute('lat');
$gpx_trkpt->appendChild($gpx_trkpt_lat);
$gpx_trkpt_lat_text = $dom_gpx->createTextNode($lat);
$gpx_trkpt_lat->appendChild($gpx_trkpt_lat_text);
$gpx_trkpt_lon = $dom_gpx->createAttribute('lon');
$gpx_trkpt->appendChild($gpx_trkpt_lon);
$gpx_trkpt_lon_text = $dom_gpx->createTextNode($lng);
$gpx_trkpt_lon->appendChild($gpx_trkpt_lon_text);
$gpx_time = $dom_gpx->createElement('time');
$gpx_time = $gpx_trkpt->appendChild($gpx_time);
$gpx_time_text = $dom_gpx->createTextNode(utcdate());
$gpx_time->appendChild($gpx_time_text);
}
}
}
}
}
header("Content-Type: text/xml");
echo $dom_gpx->saveXML();
}
?>
Let me know if you find any issues.