Incorporating Google Maps
and Google Earth into your
Remote Sensing Applications
J. Freemantle
OARS Technical Meeting,
Dec 11, 2006
Outline
Overview of Google Earth
Simple examples using keyhole markup
language (kml)
Using the Google Maps/Earth API
Some community examples
Questions?
Google Earth
Client/Server Application
Free for basic version
Works on Windows (2000/XP), Mac OS
10.3.9, Linux
Google Earth Overview
Satellite and Airborne Imagery 1-3
years old
Spatial resolution in countryside < 15
m. Major US cities less than 1-2 feet
(20-40 cm).
Parts of Manhattan (Fulton Co.) 10 cm!
York University
Newmarket
Low vs high res. data (Aurora)
Toronto
New York City (20 cm)
New York City (10 cm)
10 and 20 cm images compared
Primary Data (roads etc)
Boundary Errors
Why Google?
Its free!!!
Generally up to date
Large user community
Developer/programmer friendly
Easy to learn
Platform independent
Its cool!
Assumptions/Caveats
Check the fine print of End User License
(EUL) for your situation.
Google Earth 4.0 (Beta), free version.
Public/Private data? (choose wisely).
Simple Examples using KML
Point
Pictures
Tracks
Overlays
Links to external data
Warning Code Examples!
Keyhole Markup Language (kml)
Xml grammar and file format for
describing geographic features in
google earth/maps
Points
Lines
Polygons
Models
links
Keyhole Markup Language (KML)
KML files can be shared.
KMZ files are a compressed version of
KML files.
Google Earth processes kml files like
web browsers process html files.
Kml example: Simple point
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.0">
<Placemark>
<name>OARS Meeting</name>
<description><![CDATA[Incorporating Google Maps and Google Earth
into your Remote Sensing Applications <br>
Presented by Jim Freemantle <br>Dec 11, 2006 7:00 pm <br>
Room 129 Chemistry Building, York University, Toronto.
<br>]]></description>
<Point id="khPoint616">
<coordinates>-79.508,43.773225,0</coordinates>
</Point>
</Placemark>
</kml>
Simple Point
Simple Point
Simple point, with link
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.0">
<Placemark>
<name>OARS Meeting</name>
<description><![CDATA[Incorporating Google Maps and Google Earth
into your Remote Sensing Applications <br>
<a href=“http://www.oars.on.ca/meetings.php”> details </a>
<br>]]></description>
<Point id="khPoint616">
<coordinates>-79.508,43.773225,0</coordinates>
</Point>
</Placemark>
</kml>
Simple point with link
Simple point, with image
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.0">
<Placemark>
<name>OARS Meeting</name>
<description><![CDATA[Incorporating Google Maps and Google Earth
into your Remote Sensing Applications <br>
<a href=“http://www.oars.on.ca/meetings.php”> details </a>
<br>
<img src="c:/documents and settings/user/my documents/my
pictures/jim_pic.jpg"/>]]></description>
<Point id="khPoint616">
<coordinates>-79.508,43.773225,0</coordinates>
</Point>
</Placemark>
</kml>
Simple point with image
Track
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.0">
<Document>
<name>t0490f13</name>
<Placemark>
<name>t0490f13</name>
<description><![CDATA[Flight Line 13 tape 490 CASI 2001 <br>]]></description>
<LineString>
<coordinates>-68.8911,48.79734,2470.74 -68.8947,48.79449,2471.35 </coordinates>
<coordinates> -68.9127, 48.78028,2466.96,-68.9164,48.77747,2469.82 </coordinates>
</LineString>
</Placemark>
</Document>
</kml>
Track
Track
GeoTagging
GeoTagging
Requirements
GPS device
Camera with EXIF format jpg files and
internal clock
Software to sync gps track with time of
photo
Software to create google earth file (.kml)
GeoTagging
GPS Devices Used
Sony GPS-SC1 ($129.00)
Garmin Forerunner 201
Runners GPS ($159.00)
GeoTagging
Software Used
GPSBabel (NMEA to GPX)
GPS Image Tracker (Sony) (Not required)
iTag
GeoTagging
GeoTagging
GeoTagging
Overlays
Getting your georeferenced data into
Google Earth
Need georeferenced data
Manually imported, as a jpg image, and
matched to Google Earth
Overlays
Overlays
Links
Images
External websites via url
Databases
Track with link
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.0">
<Document>
<name>t0489f06</name>
<Placemark>
<name>t0489f06</name>
<description><![CDATA[Flight Line 06 tape 489 CASI 2001 <br>
<a href="http://www.aerocan.net/tapedb.xml#489"> Link to Flight Log </a>
<br>]]></description>
<LineString>
<coordinates>-68.8911,48.79734,2470.74 -68.8947,48.79449,2471.35 </coordinates>
<coordinates> -68.9127, 48.78028,2466.96,-68.9164,48.77747,2469.82 </coordinates>
</LineString>
</Placemark>
</Document>
</kml>
Track with link
Point with link
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.0">
<Placemark>
<name>Waskesiu</name>
<description><![CDATA[Aeronet Sites Worldwide
<br><a href="http://aeronet.gsfc.nasa.gov/cgi-bin/
type_one_station_opera_v2_new?site=Waskesiu&nachal=2&aero_water=0&level=1
&if_day=0&year_or_month=0">Link to Waskesiu data</a><br>]]></description>
<Point id="khPoint616">
<coordinates>-106.083,53.916698,550</coordinates>
</Point>
</Placemark>
</kml>
Point
with
Link
Google Earth/Map Application
Programmer Interface (API)
Sign up for your key
Can be used only on requested web
accessible directory eg.
http://www.example.com/gmaps
Receive example script and put it in
that directory
Build Google Map applications from
there
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8"/>
<title>Jim's Google Maps JavaScript API Example from M. Brown</title>
<script src="http://maps.google.com/maps?file=api&amp;v=2&amp;key=xxx"
type="text/javascript"></script>
<script type="text/javascript">
//<![CDATA[
var largemapcontrol = new GLargeMapControl();
function load() {
if (GBrowserIsCompatible()) {
var map = new GMap(document.getElementById("map"));
GEvent.addListener(map,'click',function(overlay,point) {
var latLngStr = '(' + point.x + ', '+ point.y + ')<br/>';
var message = document.getElementById("message");
message.innerHTML = latLngStr;
});
map.centerAndZoom(new GPoint(-79.505, 43.77382), 4);
map.addControl(largemapcontrol);
}
}
//]]>
</script>
</head>
<body onload="load()" onunload="GUnload()">
<div id="map" style="width: 500px; height: 300px"></div>
<div id="message"></div>
</body>
</html>
Google Map API
Google Earth API
Link to dynamically generated kml
No API key required
See
http://earth.google.com/kml/kml_tut.ht
ml#tracking_point
Google Earth Example
<?php
// get the time
$timesnap = date("H:i:s");
$BOX=$_GET[BBOX];
// split the client's BBOX return by commas and spaces to obtain an array of coordinates
$coords = preg_split('/,|\s/', $BOX);
// for clarity, place each coordinate into a clearly marked bottom_left or top_right variable
$bl_lon = $coords[0];
$bl_lat = $coords[1];
$tr_lon = $coords[2];
$tr_lat = $coords[3];
// calculate the approx center of the view -- note that this is innaccurate if the user is not looking straight down
$userlon = (($coords[2] - $coords[0])/2) + $coords[0];
$userlat = (($coords[3] - $coords[1])/2) + $coords[1];
$response = '<?xml version="1.0" encoding="UTF-8"?>';
$response .= '<kml xmlns="http://earth.google.com/kml/2.0">';
$response .= '<Placemark>';
$response .= '<name>'.$timesnap.'</name>';
$response .= '<Point>';
$response .= "<coordinates>$userlon,$userlat,0</coordinates>";
$response .= '</Point>';
$response .= '</Placemark>';
$response .= '</kml>';
echo $response;
?>
Examples from the Community
“Mashups”
Acknowledgements
Data providers
J. Miller (York U), A. Smith (Agr. Canada)
Colleagues
I. Lumb, L. Gray
Resources
http://earth.google.com
http://maps.google.com
http://www.oars.on.ca
“Hacking Google Maps and Google
Earth” by Martin C. Brown
Check back on the OARS website for a
copy of these slides and list url of useful
links
Resources
Interesting links
GeoTagging "adding location information to pictures"
http://www.iceburnslair.com/mapper/
http://wwmx.org/Download.aspx
http://www.oziphototool.com//
http://www.gpsbabel.org/
http://itagsoftware.awswa.com/
Interesting discussion at Canadian Canoe Routes on this topic:
http://www.myccr.com/SectionForums/viewtopic.php?p=183038
Mashups:
http://www.beerhunter.ca/OttawaArea
http://googlemapsmania.blogspot.com/
Questions?