http://maps.google.com/staticmap?center=31.494445,74.334011&zoom=15&size=256×256&maptype=mapmaker-Roadmap&key=API_KEY&sensor=false

As I had a quiet evening ahead of me I decided I wanted to export my tracks to kmz format for overlay in Google Earth and/or Google Maps. With this file I wanted to add placemarks including links to video highlights. Is that too much to ask for one evening? Not really…

First of all I downloaded my tracks from the GPS through my USB cable using the wonderful Garmin MapSource program. After having selected the tracks I wanted to include I exported them as a gpx file, the open GPS eXchange Format.

Newer versions of Google Earth support direct loading of gpx files but they did not work well in my case. So I used the free GPS Visualizer tool which does a wonderful job of turning my gpx file into a kmz file including nice colouring of the different track content.

All that remained was adding the placemarks in Google Earth which we visited. For some I embedded the YouTube code to the Placemark Description folder as neatly outlined in the Google Earth Outreach tutorial. Had to upgrade to Google Earth 4.2.0198.2451 (beta) before my videos showed up. And voila! Mission accomplished!

Okay, I did already have raw video material sitting around but exporting small videos in mpeg format and uploading them was remarkably easy. Within a few minutes they were directly linkable too (though not immediately indexed yet of course).

Not bad for an evening home, another thing to tick off my hobby to do list. All I have to do now is add some more video/photo content

Download result Google Earth file

If you are using Internet Explorer you might have to change the extension of the Google Earth file from .zip to .kmz to be able to open it directly in Google Earth. Still have to make some changes to my server so that IE users don’t have to go through this hassle. Alternatively you can download Firefox web browser.

Using the MyMaps tab it is possible to add your own content to Google Maps and share this with the rest of the world! You can either add a placemark, line or shape to your map, name your map and Edit or Save it. When saving it you have the choice of making it public or private. Public maps are maps that you want to publish and share with everyone. Public maps will be included in the search results on Google Maps and Earth.

A nice new feature of Google Maps are the so called Google Mapplets which are mini applications based on Google Maps which allow you to add your own content or features. Mapplets are stored on Google’s servers and can be shared in an online official directory so that others can load up your mapplet as well.

An example is the getLatLongPlus mapplet which allows you to click on any point in the map and get the coordinates back in latitude longitude. You can also output this data in georss, kml or gpx format for integration with other applications and or GPS receivers!

So what is the advantage of having a spatial database? For one, having all your data in a central database including well defined privileges, is a great thing to have. Besides this it is possible to extend the more standard SQL queries with spatial queries. E.g. which towns lie within a zone of 100km around the epicenter of the earthquake location. But a spatial database can also be used to populate a Google Map (or other online mapping applications) as I have shown in the image here:

In the example below I connect to my PostgreSQL database by means of PHP.

$db_handle = pg_connect(”host=localhost port=5432 dbname=outbreak_locations user=mark password=whatever”);
$query = “SELECT * FROM locations”;
$result = pg_exec($db_handle, $query);

Once we have our connection it is time to generate the XML format which will be used to populate our Google Map.

header(”Content-type: text/xml”);
// Start XML file, echo parent node
echo ‘‘;
for ($row = 0; $row < pg_numrows($result); $row++) {
// ADD TO XML DOCUMENT NODE
echo ‘
echo ‘town=”‘ . parseToXML(pg_result($result, $row, ‘town’)) . ‘” ‘;
echo ‘country=”‘ . parseToXML(pg_result($result, $row, ‘country’)) . ‘” ‘;
echo ‘lat=”‘ . parseToXML(pg_result($result, $row, ‘latitude’)) . ‘” ‘;
echo ‘lon=”‘ . parseToXML(pg_result($result, $row, ‘longitude’)) . ‘” ‘;
echo ‘/>’;
}
// End XML file
echo ”;
?>

Make sure you include the parseToXML function included at the top of your php file:

function parseToXML($htmlStr)
{
$xmlStr=str_replace(’<’,'<’,$htmlStr);
$xmlStr=str_replace(’>’,'>’,$xmlStr);
$xmlStr=str_replace(’”‘,’”‘,$xmlStr);
$xmlStr=str_replace(”‘”,”’,$xmlStr);
$xmlStr=str_replace(”&”,’&’,$xmlStr);
return $xmlStr;
}

The above code is the php used to generate the XML. This php file is referred to from the index.html file which loads the actual Google Map. Besides calling the Google Map API using your own key file and declaring your marker symbols, add two functions:

function load() {
if (GBrowserIsCompatible()) {
var map = new GMap2(document.getElementById(”map”));
map.addControl(new GSmallMapControl());
map.addControl(new GMapTypeControl());
map.setCenter(new GLatLng(0, 0), 1);
GDownloadUrl(”generate_gmap_xml.php”, function(data) {
var xml = GXml.parse(data);
var markers = xml.documentElement.getElementsByTagName(”marker”);
for (var i = 0; i < markers.length; i++) {
var town = markers[i].getAttribute(”town”);
var country = markers[i].getAttribute(”country”);
var type = markers[i].getAttribute(”type”);
var point = new GLatLng(parseFloat(markers[i].getAttribute(”lat”)),
parseFloat(markers[i].getAttribute(”lon”)));
var marker = createMarker(point, country, town, type);
map.addOverlay(marker);
}
});
}
}

and

function createMarker(point, name, country, town, type) {
var marker = new GMarker(point, customIcons[type]);
var html = “” + name + “
” + country + ”
” + town + ”
” + type;
GEvent.addListener(marker, ‘click’, function() {
marker.openInfoWindowHtml(html);
});
return marker;
}

In order to add a WMS service:

1. Click on the menu item Add and choose Image Overlay
2. Click on the tab Refresh and choose WMS Parameters
3. Pick your favorite WMS server in the combo box at the top or add your own using Add

In the example here I have added Maplecroft’s Tuberculosis risk index, part of the WMS services I am setting up at Maplecroft.

Download Google Earth file